Re: [PATCH v9 13/13] media: ti: Add CSI2RX support for J721E

From: Jai Luthra
Date: Thu Oct 05 2023 - 17:29:48 EST

Hi Laurent,

Thanks for the review, and apologies for being late on getting back on
this.

On Aug 29, 2023 at 19:44:57 +0300, Laurent Pinchart wrote:
> Hi Jai,
>
> Thank you for the patch.
>
> On Fri, Aug 11, 2023 at 04:17:35PM +0530, Jai Luthra wrote:
> > From: Pratyush Yadav <p.yadav@xxxxxx>
> >
> > TI's J721E uses the Cadence CSI2RX and DPHY peripherals to facilitate
> > capture over a CSI-2 bus.
> >
> > The Cadence CSI2RX IP acts as a bridge between the TI specific parts and
> > the CSI-2 protocol parts. TI then has a wrapper on top of this bridge
> > called the SHIM layer. It takes in data from stream 0, repacks it, and
> > sends it to memory over PSI-L DMA.
> >
> > This driver acts as the "front end" to V4L2 client applications. It
> > implements the required ioctls and buffer operations, passes the
> > necessary calls on to the bridge, programs the SHIM layer, and performs
> > DMA via the dmaengine API to finally return the data to a buffer
> > supplied by the application.
> >
> > Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
> > Co-authored-by: Vaishnav Achath <vaishnav.a@xxxxxx>
> > Signed-off-by: Vaishnav Achath <vaishnav.a@xxxxxx>
> > Tested-by: Vaishnav Achath <vaishnav.a@xxxxxx>
> > Co-authored-by: Jai Luthra <j-luthra@xxxxxx>
> > Signed-off-by: Jai Luthra <j-luthra@xxxxxx>
> > ---
> > Changes since v8:
> > - Allocate drain buffer at start of stream instead of doing it in the
> > middle, and document why it is needed in comments
> > - Call subdev's get_fmt directly for link_validation()
> > - Cleanup height/width clamping and rounding code, document it in comments
> > - Return and check errors from setup_shim()
> > - s/subdev/source for cadence csi2rx's v4l2_subdev
> > - s/ti_csi2rx_init_subdev/ti_csi2rx_notifier_register
> > - Change copyright year/author list
> >
> > MAINTAINERS | 7 +
> > drivers/media/platform/ti/Kconfig | 12 +
> > drivers/media/platform/ti/Makefile | 1 +
> > drivers/media/platform/ti/j721e-csi2rx/Makefile | 2 +
> > .../media/platform/ti/j721e-csi2rx/j721e-csi2rx.c | 1150 ++++++++++++++++++++
> > 5 files changed, 1172 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 02a3192195af..959147d6d936 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -21455,6 +21455,13 @@ F: Documentation/devicetree/bindings/media/i2c/ti,ds90*
> > F: drivers/media/i2c/ds90*
> > F: include/media/i2c/ds90*
> >
> > +TI J721E CSI2RX DRIVER
> > +M: Jai Luthra <j-luthra@xxxxxx>
> > +L: linux-media@xxxxxxxxxxxxxxx
> > +S: Maintained
> > +F: Documentation/devicetree/bindings/media/ti,j721e-csi2rx.yaml
> > +F: drivers/media/platform/ti/j721e-csi2rx/
> > +
> > TI KEYSTONE MULTICORE NAVIGATOR DRIVERS
> > M: Nishanth Menon <nm@xxxxxx>
> > M: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
> > diff --git a/drivers/media/platform/ti/Kconfig b/drivers/media/platform/ti/Kconfig
> > index e1ab56c3be1f..42c908f6e1ae 100644
> > --- a/drivers/media/platform/ti/Kconfig
> > +++ b/drivers/media/platform/ti/Kconfig
> > @@ -63,6 +63,18 @@ config VIDEO_TI_VPE_DEBUG
> > help
> > Enable debug messages on VPE driver.
> >
> > +config VIDEO_TI_J721E_CSI2RX
> > + tristate "TI J721E CSI2RX wrapper layer driver"
> > + depends on VIDEO_DEV && VIDEO_V4L2_SUBDEV_API
> > + depends on MEDIA_SUPPORT && MEDIA_CONTROLLER
> > + depends on PHY_CADENCE_DPHY_RX && VIDEO_CADENCE_CSI2RX
>
> Is there a compile-time dependency on these, or just runtime ? If it's
> just at runtime, it would be nice to either drop the dependency here, or
> add a (...) || COMPILE_TEST
>

There isn't a compile-time dependency as such, but yes this IP only
works with Cadence CSI+DPHY so I will switch it to (...) ||
COMPILE_TEST.

> > + depends on ARCH_K3 || COMPILE_TEST
> > + select VIDEOBUF2_DMA_CONTIG
> > + select V4L2_FWNODE
> > + help
> > + Support for TI CSI2RX wrapper layer. This just enables the wrapper driver.
> > + The Cadence CSI2RX bridge driver needs to be enabled separately.
> > +
> > source "drivers/media/platform/ti/am437x/Kconfig"
> > source "drivers/media/platform/ti/davinci/Kconfig"
> > source "drivers/media/platform/ti/omap/Kconfig"
> > diff --git a/drivers/media/platform/ti/Makefile b/drivers/media/platform/ti/Makefile
> > index 98c5fe5c40d6..8a2f74c9380e 100644
> > --- a/drivers/media/platform/ti/Makefile
> > +++ b/drivers/media/platform/ti/Makefile
> > @@ -3,5 +3,6 @@ obj-y += am437x/
> > obj-y += cal/
> > obj-y += vpe/
> > obj-y += davinci/
> > +obj-y += j721e-csi2rx/
> > obj-y += omap/
> > obj-y += omap3isp/
> > diff --git a/drivers/media/platform/ti/j721e-csi2rx/Makefile b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> > new file mode 100644
> > index 000000000000..377afc1d6280
> > --- /dev/null
> > +++ b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> > @@ -0,0 +1,2 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +obj-$(CONFIG_VIDEO_TI_J721E_CSI2RX) += j721e-csi2rx.o
> > diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> > new file mode 100644
> > index 000000000000..301d947f6098
> > --- /dev/null
> > +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> > @@ -0,0 +1,1150 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * TI CSI2RX Shim Wrapper Driver
> > + *
> > + * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
> > + *
> > + * Author: Pratyush Yadav <p.yadav@xxxxxx>
> > + * Author: Jai Luthra <j-luthra@xxxxxx>
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/dmaengine.h>
> > +#include <linux/module.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <media/mipi-csi2.h>
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-ioctl.h>
> > +#include <media/v4l2-mc.h>
> > +#include <media/videobuf2-dma-contig.h>
> > +
> > +#define TI_CSI2RX_MODULE_NAME "j721e-csi2rx"
> > +
> > +#define SHIM_CNTL 0x10
> > +#define SHIM_CNTL_PIX_RST BIT(0)
> > +
> > +#define SHIM_DMACNTX 0x20
> > +#define SHIM_DMACNTX_EN BIT(31)
> > +#define SHIM_DMACNTX_YUV422 GENMASK(27, 26)
> > +#define SHIM_DMACNTX_SIZE GENMASK(21, 20)
> > +#define SHIM_DMACNTX_FMT GENMASK(5, 0)
> > +#define SHIM_DMACNTX_UYVY 0
> > +#define SHIM_DMACNTX_VYUY 1
> > +#define SHIM_DMACNTX_YUYV 2
> > +#define SHIM_DMACNTX_YVYU 3
> > +#define SHIM_DMACNTX_SIZE_8 0
> > +#define SHIM_DMACNTX_SIZE_16 1
> > +#define SHIM_DMACNTX_SIZE_32 2
> > +
> > +#define SHIM_PSI_CFG0 0x24
> > +#define SHIM_PSI_CFG0_SRC_TAG GENMASK(15, 0)
> > +#define SHIM_PSI_CFG0_DST_TAG GENMASK(31, 16)
> > +
> > +#define PSIL_WORD_SIZE_BYTES 16
> > +/*
> > + * There are no hard limits on the width or height. The DMA engine can handle
> > + * all sizes. The max width and height are arbitrary numbers for this driver.
> > + * Use 16K * 16K as the arbitrary limit. It is large enough that it is unlikely
> > + * the limit will be hit in practice.
> > + */
> > +#define MAX_WIDTH_BYTES SZ_16K
> > +#define MAX_HEIGHT_LINES SZ_16K
> > +
> > +#define DRAIN_TIMEOUT_MS 50
> > +
> > +struct ti_csi2rx_fmt {
> > + u32 fourcc; /* Four character code. */
> > + u32 code; /* Mbus code. */
> > + u32 csi_dt; /* CSI Data type. */
> > + u8 bpp; /* Bits per pixel. */
> > + u8 size; /* Data size shift when unpacking. */
> > +};
> > +
> > +struct ti_csi2rx_buffer {
> > + /* Common v4l2 buffer. Must be first. */
> > + struct vb2_v4l2_buffer vb;
> > + struct list_head list;
> > + struct ti_csi2rx_dev *csi;
> > +};
> > +
> > +enum ti_csi2rx_dma_state {
> > + TI_CSI2RX_DMA_STOPPED, /* Streaming not started yet. */
> > + TI_CSI2RX_DMA_IDLE, /* Streaming but no pending DMA operation. */
> > + TI_CSI2RX_DMA_ACTIVE, /* Streaming and pending DMA operation. */
> > +};
> > +
> > +struct ti_csi2rx_dma {
> > + /* Protects all fields in this struct. */
> > + spinlock_t lock;
> > + struct dma_chan *chan;
> > + /* Buffers queued to the driver, waiting to be processed by DMA. */
> > + struct list_head queue;
> > + enum ti_csi2rx_dma_state state;
> > + /*
> > + * Queue of buffers submitted to DMA engine.
> > + */
> > + struct list_head submitted;
> > + /* Buffer to drain stale data from PSI-L endpoint */
> > + struct {
> > + void *vaddr;
> > + dma_addr_t paddr;
> > + size_t len;
> > + } drain;
> > +};
> > +
> > +struct ti_csi2rx_dev {
> > + struct device *dev;
> > + void __iomem *shim;
> > + struct v4l2_device v4l2_dev;
> > + struct video_device vdev;
> > + struct media_device mdev;
> > + struct media_pipeline pipe;
> > + struct media_pad pad;
> > + struct v4l2_async_notifier notifier;
> > + struct v4l2_subdev *source;
> > + struct vb2_queue vidq;
> > + struct mutex mutex; /* To serialize ioctls. */
> > + struct v4l2_format v_fmt;
> > + struct ti_csi2rx_dma dma;
> > + u32 sequence;
> > +};
> > +
> > +static const struct ti_csi2rx_fmt formats[] = {
>
> It would be nice to prefix local symbols to avoid namespace clashes,
> even if they're static. ti_csi2rx_formats could be a good name. Same
> below where applicable, and possibly above for some macro names.
>

Will fix.

> > + {
> > + .fourcc = V4L2_PIX_FMT_YUYV,
> > + .code = MEDIA_BUS_FMT_YUYV8_1X16,
> > + .csi_dt = MIPI_CSI2_DT_YUV422_8B,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_UYVY,
> > + .code = MEDIA_BUS_FMT_UYVY8_1X16,
> > + .csi_dt = MIPI_CSI2_DT_YUV422_8B,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_YVYU,
> > + .code = MEDIA_BUS_FMT_YVYU8_1X16,
> > + .csi_dt = MIPI_CSI2_DT_YUV422_8B,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_VYUY,
> > + .code = MEDIA_BUS_FMT_VYUY8_1X16,
> > + .csi_dt = MIPI_CSI2_DT_YUV422_8B,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SBGGR8,
> > + .code = MEDIA_BUS_FMT_SBGGR8_1X8,
> > + .csi_dt = MIPI_CSI2_DT_RAW8,
> > + .bpp = 8,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SGBRG8,
> > + .code = MEDIA_BUS_FMT_SGBRG8_1X8,
> > + .csi_dt = MIPI_CSI2_DT_RAW8,
> > + .bpp = 8,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SGRBG8,
> > + .code = MEDIA_BUS_FMT_SGRBG8_1X8,
> > + .csi_dt = MIPI_CSI2_DT_RAW8,
> > + .bpp = 8,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SRGGB8,
> > + .code = MEDIA_BUS_FMT_SRGGB8_1X8,
> > + .csi_dt = MIPI_CSI2_DT_RAW8,
> > + .bpp = 8,
> > + .size = SHIM_DMACNTX_SIZE_8,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SBGGR10,
> > + .code = MEDIA_BUS_FMT_SBGGR10_1X10,
> > + .csi_dt = MIPI_CSI2_DT_RAW10,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_16,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SGBRG10,
> > + .code = MEDIA_BUS_FMT_SGBRG10_1X10,
> > + .csi_dt = MIPI_CSI2_DT_RAW10,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_16,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SGRBG10,
> > + .code = MEDIA_BUS_FMT_SGRBG10_1X10,
> > + .csi_dt = MIPI_CSI2_DT_RAW10,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_16,
> > + }, {
> > + .fourcc = V4L2_PIX_FMT_SRGGB10,
> > + .code = MEDIA_BUS_FMT_SRGGB10_1X10,
> > + .csi_dt = MIPI_CSI2_DT_RAW10,
> > + .bpp = 16,
> > + .size = SHIM_DMACNTX_SIZE_16,
> > + },
> > +
> > + /* More formats can be supported but they are not listed for now. */
> > +};
> > +
> > +static const unsigned int num_formats = ARRAY_SIZE(formats);
>
> I would use ARRAY_SIZE(formats) below and drop num_formats, as I don't
> think it improves readability, but I don't insist.
>

Will fix.

> > +
> > +/* Forward declaration needed by ti_csi2rx_dma_callback. */
> > +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> > + struct ti_csi2rx_buffer *buf);
> > +
> > +static const struct ti_csi2rx_fmt *find_format_by_pix(u32 pixelformat)
>
> Maybe "_by_fourcc" ? That's nitpicking though.
>

Will fix.

> > +{
> > + unsigned int i;
> > +
> > + for (i = 0; i < num_formats; i++) {
> > + if (formats[i].fourcc == pixelformat)
> > + return &formats[i];
> > + }
> > +
> > + return NULL;
> > +}
> > +
> > +static const struct ti_csi2rx_fmt *find_format_by_code(u32 code)
> > +{
> > + unsigned int i;
> > +
> > + for (i = 0; i < num_formats; i++) {
> > + if (formats[i].code == code)
> > + return &formats[i];
> > + }
> > +
> > + return NULL;
> > +}
> > +
> > +static void ti_csi2rx_fill_fmt(const struct ti_csi2rx_fmt *csi_fmt,
> > + struct v4l2_format *v4l2_fmt)
> > +{
> > + struct v4l2_pix_format *pix = &v4l2_fmt->fmt.pix;
> > + unsigned int pixels_in_word;
> > + u8 bpp = ALIGN(csi_fmt->bpp, 8);
>
> All bpp values are multiple of 8, is ALIGN() needed ?
>

Hmm you're right it's not really needed, I think I decided to keep it
from Pratyush's series just to be safe. Will remove it in v10.

> > +
> > + pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> > +
> > + /* Clamp width and height to sensible maximums (16K x 16K) */
> > + pix->width = clamp_t(unsigned int, pix->width,
> > + pixels_in_word,
> > + MAX_WIDTH_BYTES * 8 / bpp);
> > + pix->height = clamp_t(unsigned int, pix->height, 1, MAX_HEIGHT_LINES);
> > +
> > + /* Width should be a multiple of transfer word-size */
> > + pix->width = rounddown(pix->width, pixels_in_word);
> > +
> > + v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > + pix->pixelformat = csi_fmt->fourcc;
> > + pix->colorspace = V4L2_COLORSPACE_SRGB;
>
> You should fill the other colorspace-related fields.
>

Good catch, I think it would be better to use the colorspace and related
fields from the mbus format of the source subdev as this IP doesn't
really change it. Will fix in v10.

> > + pix->bytesperline = pix->width * (bpp / 8);
> > + pix->sizeimage = pix->bytesperline * pix->height;
> > +}
> > +
> > +static int ti_csi2rx_querycap(struct file *file, void *priv,
> > + struct v4l2_capability *cap)
> > +{
> > + strscpy(cap->driver, TI_CSI2RX_MODULE_NAME, sizeof(cap->driver));
> > + strscpy(cap->card, TI_CSI2RX_MODULE_NAME, sizeof(cap->card));
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_enum_fmt_vid_cap(struct file *file, void *priv,
> > + struct v4l2_fmtdesc *f)
> > +{
> > + const struct ti_csi2rx_fmt *fmt = NULL;
> > +
> > + if (f->mbus_code) {
> > + /* 1-to-1 mapping between bus formats and pixel formats */
> > + if (f->index > 0)
> > + return -EINVAL;
> > +
> > + fmt = find_format_by_code(f->mbus_code);
> > + } else {
> > + if (f->index >= num_formats)
> > + return -EINVAL;
> > +
> > + fmt = &formats[f->index];
> > + }
> > +
> > + if (!fmt)
> > + return -EINVAL;
> > +
> > + f->pixelformat = fmt->fourcc;
> > + memset(f->reserved, 0, sizeof(f->reserved));
> > + f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_g_fmt_vid_cap(struct file *file, void *prov,
> > + struct v4l2_format *f)
> > +{
> > + struct ti_csi2rx_dev *csi = video_drvdata(file);
> > +
> > + *f = csi->v_fmt;
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_try_fmt_vid_cap(struct file *file, void *priv,
> > + struct v4l2_format *f)
> > +{
> > + const struct ti_csi2rx_fmt *fmt;
> > +
> > + /*
> > + * Default to the first format if the requested pixel format code isn't
> > + * supported.
> > + */
> > + fmt = find_format_by_pix(f->fmt.pix.pixelformat);
> > + if (!fmt)
> > + fmt = &formats[0];
> > +
> > + /* Interlaced formats are not supported. */
> > + f->fmt.pix.field = V4L2_FIELD_NONE;
> > +
> > + ti_csi2rx_fill_fmt(fmt, f);
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_s_fmt_vid_cap(struct file *file, void *priv,
> > + struct v4l2_format *f)
> > +{
> > + struct ti_csi2rx_dev *csi = video_drvdata(file);
> > + struct vb2_queue *q = &csi->vidq;
> > + int ret;
> > +
> > + if (vb2_is_busy(q))
> > + return -EBUSY;
> > +
> > + ret = ti_csi2rx_try_fmt_vid_cap(file, priv, f);
> > + if (ret < 0)
> > + return ret;
> > +
> > + csi->v_fmt = *f;
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_enum_framesizes(struct file *file, void *fh,
> > + struct v4l2_frmsizeenum *fsize)
> > +{
> > + const struct ti_csi2rx_fmt *fmt;
> > + unsigned int pixels_in_word;
> > + u8 bpp;
> > +
> > + fmt = find_format_by_pix(fsize->pixel_format);
> > + if (!fmt || fsize->index != 0)
> > + return -EINVAL;
> > +
> > + bpp = ALIGN(fmt->bpp, 8);
> > +
> > + /*
> > + * Number of pixels in one PSI-L word. The transfer happens in multiples
> > + * of PSI-L word sizes.
> > + */
> > + pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> > +
> > + fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
> > + fsize->stepwise.min_width = pixels_in_word;
> > + fsize->stepwise.max_width = rounddown(MAX_WIDTH_BYTES * 8 / bpp,
> > + pixels_in_word);
> > + fsize->stepwise.step_width = pixels_in_word;
> > + fsize->stepwise.min_height = 1;
> > + fsize->stepwise.max_height = MAX_HEIGHT_LINES;
> > + fsize->stepwise.step_height = 1;
> > +
> > + return 0;
> > +}
> > +
> > +static const struct v4l2_ioctl_ops csi_ioctl_ops = {
> > + .vidioc_querycap = ti_csi2rx_querycap,
> > + .vidioc_enum_fmt_vid_cap = ti_csi2rx_enum_fmt_vid_cap,
> > + .vidioc_try_fmt_vid_cap = ti_csi2rx_try_fmt_vid_cap,
> > + .vidioc_g_fmt_vid_cap = ti_csi2rx_g_fmt_vid_cap,
> > + .vidioc_s_fmt_vid_cap = ti_csi2rx_s_fmt_vid_cap,
> > + .vidioc_enum_framesizes = ti_csi2rx_enum_framesizes,
> > + .vidioc_reqbufs = vb2_ioctl_reqbufs,
> > + .vidioc_create_bufs = vb2_ioctl_create_bufs,
> > + .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> > + .vidioc_querybuf = vb2_ioctl_querybuf,
> > + .vidioc_qbuf = vb2_ioctl_qbuf,
> > + .vidioc_dqbuf = vb2_ioctl_dqbuf,
> > + .vidioc_expbuf = vb2_ioctl_expbuf,
> > + .vidioc_streamon = vb2_ioctl_streamon,
> > + .vidioc_streamoff = vb2_ioctl_streamoff,
> > +};
> > +
> > +static const struct v4l2_file_operations csi_fops = {
> > + .owner = THIS_MODULE,
> > + .open = v4l2_fh_open,
> > + .release = vb2_fop_release,
> > + .read = vb2_fop_read,
> > + .poll = vb2_fop_poll,
> > + .unlocked_ioctl = video_ioctl2,
> > + .mmap = vb2_fop_mmap,
> > +};
> > +
> > +static int csi_async_notifier_bound(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *subdev,
> > + struct v4l2_async_connection *asc)
> > +{
> > + struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> > +
> > + csi->source = subdev;
> > +
> > + return 0;
> > +}
> > +
> > +static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
> > +{
> > + struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> > + struct video_device *vdev = &csi->vdev;
> > + int ret;
> > +
> > + ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> > + if (ret)
> > + return ret;
> > +
> > + ret = v4l2_create_fwnode_links_to_pad(csi->source, &csi->pad,
> > + MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
> > +
> > + if (ret) {
> > + video_unregister_device(vdev);
> > + return ret;
> > + }
> > +
> > + return v4l2_device_register_subdev_nodes(&csi->v4l2_dev);
>
> You should call video_unregister_device() if this fails.

Will fix.

>
> I'm tempted, however, to register the video device at probe time, not in
> this function.
>

My guess is this was done here to prevent creating a video node if
sensor (source subdev) failed to probe. With multistream support we will
have multiple video nodes (upto 16) where it seems cleaner to wait for
the source. Let me know if you had some other reason in mind.

> > +}
> > +
> > +static const struct v4l2_async_notifier_operations csi_async_notifier_ops = {
> > + .bound = csi_async_notifier_bound,
> > + .complete = csi_async_notifier_complete,
> > +};
> > +
> > +static int ti_csi2rx_notifier_register(struct ti_csi2rx_dev *csi)
> > +{
> > + struct fwnode_handle *fwnode;
> > + struct v4l2_async_connection *asc;
> > + struct device_node *node;
> > + int ret;
> > +
> > + node = of_get_child_by_name(csi->dev->of_node, "csi-bridge");
> > + if (!node)
> > + return -EINVAL;
> > +
> > + fwnode = of_fwnode_handle(node);
> > + if (!fwnode) {
> > + of_node_put(node);
> > + return -EINVAL;
> > + }
> > +
> > + v4l2_async_nf_init(&csi->notifier, &csi->v4l2_dev);
> > + csi->notifier.ops = &csi_async_notifier_ops;
> > +
> > + asc = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> > + struct v4l2_async_connection);
> > + of_node_put(node);
> > + if (IS_ERR(asc)) {
> > + v4l2_async_nf_cleanup(&csi->notifier);
> > + return PTR_ERR(asc);
> > + }
> > +
> > + ret = v4l2_async_nf_register(&csi->notifier);
> > + if (ret) {
> > + v4l2_async_nf_cleanup(&csi->notifier);
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_setup_shim(struct ti_csi2rx_dev *csi)
> > +{
> > + const struct ti_csi2rx_fmt *fmt;
> > + unsigned int reg;
> > +
> > + fmt = find_format_by_pix(csi->v_fmt.fmt.pix.pixelformat);
> > + if (!fmt) {
> > + dev_err(csi->dev, "Pixelformat 0x%x is not supported\n",
>
> Use %p4cc to print a fourcc. You need to pass the pixel format by
> address to dev_err() then, not by value.
>
> Can this happen though, given that the set format handler should never
> allow setting a format not supported by the driver ? I think I'd drop
> the error check. The function can then become a void function.
>

Makes sense, will drop this.

> > + csi->v_fmt.fmt.pix.pixelformat);
> > + return -EINVAL;
> > + }
> > +
> > + /* De-assert the pixel interface reset. */
> > + reg = SHIM_CNTL_PIX_RST;
> > + writel(reg, csi->shim + SHIM_CNTL);
> > +
> > + reg = SHIM_DMACNTX_EN;
> > + reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_dt);
> > +
> > + /*
> > + * Using the values from the documentation gives incorrect ordering for
> > + * the luma and chroma components. In practice, the "reverse" format
> > + * gives the correct image. So for example, if the image is in UYVY, the
> > + * reverse would be YVYU.
> > + */
> > + switch (fmt->fourcc) {
> > + case V4L2_PIX_FMT_UYVY:
> > + reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > + SHIM_DMACNTX_YVYU);
> > + break;
> > + case V4L2_PIX_FMT_VYUY:
> > + reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > + SHIM_DMACNTX_YUYV);
> > + break;
> > + case V4L2_PIX_FMT_YUYV:
> > + reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > + SHIM_DMACNTX_VYUY);
> > + break;
> > + case V4L2_PIX_FMT_YVYU:
> > + reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > + SHIM_DMACNTX_UYVY);
> > + break;
> > + default:
> > + /* Ignore if not YUV 4:2:2 */
> > + break;
> > + }
> > +
> > + reg |= FIELD_PREP(SHIM_DMACNTX_SIZE, fmt->size);
> > +
> > + writel(reg, csi->shim + SHIM_DMACNTX);
> > +
> > + reg = FIELD_PREP(SHIM_PSI_CFG0_SRC_TAG, 0) |
> > + FIELD_PREP(SHIM_PSI_CFG0_DST_TAG, 0);
> > + writel(reg, csi->shim + SHIM_PSI_CFG0);
> > +
> > + return 0;
> > +}
> > +
> > +static void ti_csi2rx_drain_callback(void *param)
> > +{
> > + struct completion *drain_complete = param;
> > +
> > + complete(drain_complete);
> > +}
> > +
> > +/** Drain the stale data left at the PSI-L endpoint.
>
> This isn't kerneldoc, so
>
> /*
> * Drain the stale data left at the PSI-L endpoint.
>

Will fix.

> > + *
> > + * This might happen if no buffers are queued in time but source is still
> > + * streaming. Or rarely it may happen while stopping the stream. To prevent
> > + * that stale data corrupting the subsequent transactions, it is required to
> > + * issue DMA requests to drain it out.
> > + */
> > +static int ti_csi2rx_drain_dma(struct ti_csi2rx_dev *csi)
> > +{
> > + struct dma_async_tx_descriptor *desc;
> > + struct completion drain_complete;
> > + dma_cookie_t cookie;
> > + int ret;
> > +
> > + init_completion(&drain_complete);
> > +
> > + desc = dmaengine_prep_slave_single(csi->dma.chan, csi->dma.drain.paddr,
> > + csi->dma.drain.len, DMA_DEV_TO_MEM,
> > + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> > + if (!desc) {
> > + ret = -EIO;
> > + goto out;
> > + }
> > +
> > + desc->callback = ti_csi2rx_drain_callback;
> > + desc->callback_param = &drain_complete;
> > +
> > + cookie = dmaengine_submit(desc);
> > + ret = dma_submit_error(cookie);
> > + if (ret)
> > + goto out;
> > +
> > + dma_async_issue_pending(csi->dma.chan);
> > +
> > + if (!wait_for_completion_timeout(&drain_complete,
> > + msecs_to_jiffies(DRAIN_TIMEOUT_MS))) {
> > + dmaengine_terminate_sync(csi->dma.chan);
> > + ret = -ETIMEDOUT;
> > + goto out;
> > + }
> > +out:
> > + return ret;
> > +}
> > +
> > +static void ti_csi2rx_dma_callback(void *param)
> > +{
> > + struct ti_csi2rx_buffer *buf = param;
> > + struct ti_csi2rx_dev *csi = buf->csi;
> > + struct ti_csi2rx_dma *dma = &csi->dma;
> > + unsigned long flags;
> > +
> > + /*
> > + * TODO: Derive the sequence number from the CSI2RX frame number
> > + * hardware monitor registers.
> > + */
> > + buf->vb.vb2_buf.timestamp = ktime_get_ns();
> > + buf->vb.sequence = csi->sequence++;
> > +
> > + spin_lock_irqsave(&dma->lock, flags);
> > +
> > + WARN_ON(!list_is_first(&buf->list, &dma->submitted));
> > + vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> > + list_del(&buf->list);
> > +
> > + /* If there are more buffers to process then start their transfer. */
> > + while (!list_empty(&dma->queue)) {
> > + buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> > +
> > + if (ti_csi2rx_start_dma(csi, buf)) {
> > + dev_err(csi->dev, "Failed to queue the next buffer for DMA\n");
> > + vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> > + } else {
> > + list_move_tail(&buf->list, &dma->submitted);
> > + }
> > + }
> > +
> > + if (list_empty(&dma->submitted))
> > + dma->state = TI_CSI2RX_DMA_IDLE;
> > +
> > + spin_unlock_irqrestore(&dma->lock, flags);
> > +}
> > +
> > +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> > + struct ti_csi2rx_buffer *buf)
> > +{
> > + unsigned long addr;
> > + struct dma_async_tx_descriptor *desc;
> > + size_t len = csi->v_fmt.fmt.pix.sizeimage;
> > + dma_cookie_t cookie;
> > + int ret = 0;
> > +
> > + addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> > + desc = dmaengine_prep_slave_single(csi->dma.chan, addr, len,
> > + DMA_DEV_TO_MEM,
> > + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> > + if (!desc)
> > + return -EIO;
> > +
> > + desc->callback = ti_csi2rx_dma_callback;
> > + desc->callback_param = buf;
> > +
> > + cookie = dmaengine_submit(desc);
> > + ret = dma_submit_error(cookie);
> > + if (ret)
> > + return ret;
> > +
> > + dma_async_issue_pending(csi->dma.chan);
> > +
> > + return 0;
> > +}
> > +
> > +static void ti_csi2rx_cleanup_buffers(struct ti_csi2rx_dev *csi,
> > + enum vb2_buffer_state buf_state)
> > +{
> > + struct ti_csi2rx_dma *dma = &csi->dma;
> > + struct ti_csi2rx_buffer *buf, *tmp;
> > + enum ti_csi2rx_dma_state state;
> > + unsigned long flags;
> > + int ret;
> > +
> > + spin_lock_irqsave(&dma->lock, flags);
> > + state = csi->dma.state;
> > + dma->state = TI_CSI2RX_DMA_STOPPED;
> > + spin_unlock_irqrestore(&dma->lock, flags);
> > +
> > + if (state != TI_CSI2RX_DMA_STOPPED) {
> > + /*
> > + * Normal DMA termination sometimes does not clean up pending
> > + * data on the endpoint.
> > + */
> > + ret = ti_csi2rx_drain_dma(csi);
> > + if (ret)
> > + dev_dbg(csi->dev,
> > + "Failed to drain DMA. Next frame might be bogus\n");
>
> A dev_warn() may be more appropriate, this seems quite important.
>

I think this was intentional. The calls to DMA engine for draining
always "timeout" even when the drain is successful, because the amount
of data drained is non-deterministic (and we use framesize to be safe,
which is much more than what FIFOs would be storing). Keeping this as
dev_warn() leads to spurious dmesg logs at the end of every stream
close.

Maybe we should use dev_dbg for the timeout case, and dev_err for any
other error thrown by DMA engine. Will fix that in v10.

Hopefully this will be simplified once we have an API in place to signal
drain to "/dev/null".

> > + }
>
> A blank line would be nice here.
>

Will fix.

> > + ret = dmaengine_terminate_sync(csi->dma.chan);
> > + if (ret)
> > + dev_err(csi->dev, "Failed to stop DMA: %d\n", ret);
>
> When called from ti_csi2rx_start_streaming() there's already a
> dmaengine_terminate_sync(), and there's also a call to the same function
> in ti_csi2rx_drain_dma() called above. Could we avoid calling the
> function multiple times ? I think stopping the DMA engine should be
> moved to a separate function, as it doesn't fit with the
> ti_csi2rx_cleanup_buffers() name.
>

Oops missed that, will fix.

> > +
> > + dma_free_coherent(csi->dev, dma->drain.len,
> > + dma->drain.vaddr, dma->drain.paddr);
> > + dma->drain.vaddr = NULL;
> > +
> > + spin_lock_irqsave(&dma->lock, flags);
> > + list_for_each_entry_safe(buf, tmp, &csi->dma.queue, list) {
> > + list_del(&buf->list);
> > + vb2_buffer_done(&buf->vb.vb2_buf, buf_state);
> > + }
> > + list_for_each_entry_safe(buf, tmp, &csi->dma.submitted, list) {
> > + list_del(&buf->list);
> > + vb2_buffer_done(&buf->vb.vb2_buf, buf_state);
> > + }
> > + spin_unlock_irqrestore(&dma->lock, flags);
> > +}
> > +
> > +static int ti_csi2rx_queue_setup(struct vb2_queue *q, unsigned int *nbuffers,
> > + unsigned int *nplanes, unsigned int sizes[],
> > + struct device *alloc_devs[])
> > +{
> > + struct ti_csi2rx_dev *csi = vb2_get_drv_priv(q);
> > + unsigned int size = csi->v_fmt.fmt.pix.sizeimage;
> > +
> > + if (*nplanes) {
> > + if (sizes[0] < size)
> > + return -EINVAL;
> > + size = sizes[0];
> > + }
> > +
> > + *nplanes = 1;
> > + sizes[0] = size;
> > +
> > + return 0;
> > +}
> > +
> > +static int ti_csi2rx_buffer_prepare(struct vb2_buffer *vb)
> > +{
> > + struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> > + unsigned long size = csi->v_fmt.fmt.pix.sizeimage;
> > +
> > + if (vb2_plane_size(vb, 0) < size) {
> > + dev_err(csi->dev, "Data will not fit into plane\n");
> > + return -EINVAL;
> > + }
> > +
> > + vb2_set_plane_payload(vb, 0, size);
> > + return 0;
> > +}
> > +
> > +static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
> > +{
> > + struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> > + struct ti_csi2rx_buffer *buf;
> > + struct ti_csi2rx_dma *dma = &csi->dma;
> > + bool restart_dma = false;
> > + unsigned long flags = 0;
> > + int ret;
> > +
> > + buf = container_of(vb, struct ti_csi2rx_buffer, vb.vb2_buf);
> > + buf->csi = csi;
> > +
> > + spin_lock_irqsave(&dma->lock, flags);
> > + /*
> > + * Usually the DMA callback takes care of queueing the pending buffers.
> > + * But if DMA has stalled due to lack of buffers, restart it now.
> > + */
> > + if (dma->state == TI_CSI2RX_DMA_IDLE) {
> > + /*
> > + * Do not restart DMA with the lock held because
> > + * ti_csi2rx_drain_dma() might block for completion.
> > + * There won't be a race on queueing DMA anyway since the
> > + * callback is not being fired.
> > + */
> > + restart_dma = true;
> > + dma->state = TI_CSI2RX_DMA_ACTIVE;
> > + } else {
> > + list_add_tail(&buf->list, &dma->queue);
> > + }
> > + spin_unlock_irqrestore(&dma->lock, flags);
> > +
> > + if (restart_dma) {
> > + /*
> > + * Once frames start dropping, some data gets stuck in the DMA
> > + * pipeline somewhere. So the first DMA transfer after frame
> > + * drops gives a partial frame. This is obviously not useful to
> > + * the application and will only confuse it. Issue a DMA
> > + * transaction to drain that up.
> > + */
>
> Another option would be to return the frame to userspace with the error
> flag set. That would give an earlier indication to applications that
> something went wrong. Up to you.
>

Oh I see, that does sound cleaner to me - I will try that out with
different applications. If it works, would it be okay if I handle it as
a separate series? The mechanism in this series is already well-tested,
even if a bit ugly.

> > + ret = ti_csi2rx_drain_dma(csi);
> > + if (ret)
> > + dev_warn(csi->dev,
> > + "Failed to drain DMA. Next frame might be bogus\n");
> > +
> > + ret = ti_csi2rx_start_dma(csi, buf);
> > + if (ret) {
> > + dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> > + spin_lock_irqsave(&dma->lock, flags);
> > + vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> > + dma->state = TI_CSI2RX_DMA_IDLE;
> > + spin_unlock_irqrestore(&dma->lock, flags);
> > + } else {
> > + spin_lock_irqsave(&dma->lock, flags);
> > + list_add_tail(&buf->list, &dma->submitted);
> > + spin_unlock_irqrestore(&dma->lock, flags);
> > + }
> > + }

[snip]

>
> -- Regards,
>
> Laurent Pinchart

--
Thanks,
Jai

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