Re: [PATCH v5 3/8] drm: rcar-du: Add support for CMM
From: Laurent Pinchart
Date: Tue Oct 15 2019 - 13:25:32 EST
Hi Jacopo,
Thank you for the patch.
On Tue, Oct 15, 2019 at 12:46:16PM +0200, Jacopo Mondi wrote:
> Add a driver for the R-Car Display Unit Color Correction Module.
>
> In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
> to perform image enhancement and color correction.
>
> Add support for CMM through a driver that supports configuration of
> the 1-dimensional LUT table. More advanced CMM features will be
> implemented on top of this initial one.
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> drivers/gpu/drm/rcar-du/Kconfig | 7 +
> drivers/gpu/drm/rcar-du/Makefile | 1 +
> drivers/gpu/drm/rcar-du/rcar_cmm.c | 198 +++++++++++++++++++++++++++++
> drivers/gpu/drm/rcar-du/rcar_cmm.h | 60 +++++++++
> 4 files changed, 266 insertions(+)
> create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.c
> create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.h
>
> diff --git a/drivers/gpu/drm/rcar-du/Kconfig b/drivers/gpu/drm/rcar-du/Kconfig
> index 1529849e217e..539d232790d1 100644
> --- a/drivers/gpu/drm/rcar-du/Kconfig
> +++ b/drivers/gpu/drm/rcar-du/Kconfig
> @@ -13,6 +13,13 @@ config DRM_RCAR_DU
> Choose this option if you have an R-Car chipset.
> If M is selected the module will be called rcar-du-drm.
>
> +config DRM_RCAR_CMM
> + bool "R-Car DU Color Management Module (CMM) Support"
> + depends on DRM && OF
> + depends on DRM_RCAR_DU
> + help
> + Enable support for R-Car Color Management Module (CMM).
> +
> config DRM_RCAR_DW_HDMI
> tristate "R-Car DU Gen3 HDMI Encoder Support"
> depends on DRM && OF
> diff --git a/drivers/gpu/drm/rcar-du/Makefile b/drivers/gpu/drm/rcar-du/Makefile
> index 6c2ed9c46467..4d1187ccc3e5 100644
> --- a/drivers/gpu/drm/rcar-du/Makefile
> +++ b/drivers/gpu/drm/rcar-du/Makefile
> @@ -15,6 +15,7 @@ rcar-du-drm-$(CONFIG_DRM_RCAR_LVDS) += rcar_du_of.o \
> rcar-du-drm-$(CONFIG_DRM_RCAR_VSP) += rcar_du_vsp.o
> rcar-du-drm-$(CONFIG_DRM_RCAR_WRITEBACK) += rcar_du_writeback.o
>
> +obj-$(CONFIG_DRM_RCAR_CMM) += rcar_cmm.o
> obj-$(CONFIG_DRM_RCAR_DU) += rcar-du-drm.o
> obj-$(CONFIG_DRM_RCAR_DW_HDMI) += rcar_dw_hdmi.o
> obj-$(CONFIG_DRM_RCAR_LVDS) += rcar_lvds.o
> diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.c b/drivers/gpu/drm/rcar-du/rcar_cmm.c
> new file mode 100644
> index 000000000000..9675a8587dee
> --- /dev/null
> +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.c
> @@ -0,0 +1,198 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * rcar_cmm.c -- R-Car Display Unit Color Management Module
> + *
> + * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> + */
> +
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include <drm/drm_color_mgmt.h>
> +
> +#include "rcar_cmm.h"
> +
> +#define CM2_LUT_CTRL 0x0000
> +#define CM2_LUT_CTRL_LUT_EN BIT(0)
> +#define CM2_LUT_TBL_BASE 0x0600
> +#define CM2_LUT_TBL(__i) (CM2_LUT_TBL_BASE + (__i) * 4)
> +
> +struct rcar_cmm {
> + void __iomem *base;
> +
> + /*
> + * @lut: 1D-LUT status
s/status/state/ ?
> + * @lut.enabled: 1D-LUT enabled flag
> + */
> + struct {
> + bool enabled;
> + } lut;
> +};
> +
> +static inline int rcar_cmm_read(struct rcar_cmm *rcmm, u32 reg)
> +{
> + return ioread32(rcmm->base + reg);
> +}
> +
> +static inline void rcar_cmm_write(struct rcar_cmm *rcmm, u32 reg, u32 data)
> +{
> + iowrite32(data, rcmm->base + reg);
> +}
> +
> +/*
> + * rcar_cmm_lut_write() - Scale the DRM LUT table entries to hardware precision
> + * and write to the CMM registers.
Some of you brief descriptions end with a period, some don't. I don't
have a preference, but could you please pick one option and use it
consistently ?
> + * @rcmm: Pointer to the CMM device
> + * @drm_lut: Pointer to the DRM LUT table
> + */
> +static void rcar_cmm_lut_write(struct rcar_cmm *rcmm,
> + const struct drm_color_lut *drm_lut)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < CM2_LUT_SIZE; ++i) {
> + u32 entry = drm_color_lut_extract(drm_lut[i].red, 8) << 16
As reported by Kieran, s/= /= /
> + | drm_color_lut_extract(drm_lut[i].green, 8) << 8
> + | drm_color_lut_extract(drm_lut[i].blue, 8);
> +
> + rcar_cmm_write(rcmm, CM2_LUT_TBL(i), entry);
> + }
> +}
> +
> +/*
> + * rcar_cmm_setup() - Configure the CMM unit.
> + * @pdev: The platform device associated with the CMM instance
> + * @config: The CMM unit configuration
> + *
> + * Configure the CMM unit with the given configuration. Currently enabling,
> + * disabling and programming of the 1-D LUT unit is supported.
> + */
> +int rcar_cmm_setup(struct platform_device *pdev,
> + const struct rcar_cmm_config *config)
> +{
> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> +
> + /* Disable LUT if requested. */
> + if (!config->lut.enable) {
> + if (rcmm->lut.enabled) {
> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
> + rcmm->lut.enabled = false;
> + }
> +
> + return 0;
> + }
> +
> + /* Enable LUT and program the new gamma table values. */
> + if (!rcmm->lut.enabled) {
> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_LUT_EN);
> + rcmm->lut.enabled = true;
> + }
> +
> + rcar_cmm_lut_write(rcmm, config->lut.table);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_setup);
> +
> +/*
> + * rcar_cmm_enable() - Enable the CMM unit.
> + * @pdev: The platform device associated with the CMM instance
> + *
> + * Enable the CMM unit by enabling the parent clock.
It would be better to explain how the function should be used rather
than what it does internally.
* Enable the CMM unit. When the output of the corresponding DU channel is
* routed to the CMM unit, the unit shall be enabled before the DU channel is
* started, and remain enabled until the channel is stopped. The CMM unit shall
* the be disabled with rcar_cmm_disable().
*
* Calls to rcar_cmm_enable() and rcar_cmm_disable() are not reference-counted.
* It is an error to attempt to enable an already enabled CMM unit, or to
* attempt to disable a disabled unit.
The relationship with rcar_cmm_setup() should also be documented.
Looking at the code, I believe rcar_cmm_enable() has to be called first,
otherwise the CMM MSTP will be disabled, and registers can't be
accessed. I would document this as part of the rcar_cmm_setup()
function.
> + */
> +int rcar_cmm_enable(struct platform_device *pdev)
> +{
> + int ret;
> +
> + ret = pm_runtime_get_sync(&pdev->dev);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_enable);
> +
> +/*
> + * rcar_cmm_disable() - Disable the CMM unit.
> + * @pdev: The platform device associated with the CMM instance
> + *
> + * Disable the CMM unit by stopping the parent clock.
Same here, but you can simply reference rcar_cmm_enable().
* Disable the CMM unit. See rcar_cmm_enable() for usage information.
*
* Disabling the CMM unit disable all the internal processing blocks. The CMM
* state shall thus be restored with rcar_cmm_setup() when re-enabling the CMM
* unit after the next rcar_cmm_enable() call.
> + */
> +void rcar_cmm_disable(struct platform_device *pdev)
> +{
> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> +
> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
> + rcmm->lut.enabled = false;
> +
> + pm_runtime_put(&pdev->dev);
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_disable);
> +
> +/*
> + * rcar_cmm_init() - Initialize the CMM
> + * @pdev: The platform device associated with the CMM instance
> + *
> + * Return: 0 on success, -EPROBE_DEFER if the CMM is not available yet,
> + * -ENODEV if the DRM_RCAR_CMM config option is disabled
> + */
> +int rcar_cmm_init(struct platform_device *pdev)
> +{
> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> +
> + if (!rcmm)
> + return -EPROBE_DEFER;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(rcar_cmm_init);
> +
> +static int rcar_cmm_probe(struct platform_device *pdev)
> +{
> + struct rcar_cmm *rcmm;
> +
> + rcmm = devm_kzalloc(&pdev->dev, sizeof(*rcmm), GFP_KERNEL);
> + if (!rcmm)
> + return -ENOMEM;
> + platform_set_drvdata(pdev, rcmm);
> +
> + rcmm->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(rcmm->base))
> + return PTR_ERR(rcmm->base);
> +
> + pm_runtime_enable(&pdev->dev);
> +
> + return 0;
> +}
> +
> +static int rcar_cmm_remove(struct platform_device *pdev)
> +{
> + pm_runtime_disable(&pdev->dev);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id rcar_cmm_of_table[] = {
> + { .compatible = "renesas,rcar-gen3-cmm", },
> + { .compatible = "renesas,rcar-gen2-cmm", },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, rcar_cmm_of_table);
> +
> +static struct platform_driver rcar_cmm_platform_driver = {
> + .probe = rcar_cmm_probe,
> + .remove = rcar_cmm_remove,
> + .driver = {
> + .name = "rcar-cmm",
> + .of_match_table = rcar_cmm_of_table,
> + },
> +};
> +
> +module_platform_driver(rcar_cmm_platform_driver);
> +
> +MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Renesas R-Car CMM Driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.h b/drivers/gpu/drm/rcar-du/rcar_cmm.h
> new file mode 100644
> index 000000000000..358ec03cf48a
> --- /dev/null
> +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.h
> @@ -0,0 +1,60 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * rcar_cmm.h -- R-Car Display Unit Color Management Module
> + *
> + * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> + */
> +
> +#ifndef __RCAR_CMM_H__
> +#define __RCAR_CMM_H__
> +
> +#define CM2_LUT_SIZE 256
> +
> +struct drm_color_lut;
> +struct platform_device;
> +
> +/**
> + * struct rcar_cmm_config - CMM configuration
> + *
> + * @lut: 1D-LUT configuration
> + * @lut.enable: 1D-LUT enable flag
> + * @lut.table: 1D-LUT table entries
> + */
> +struct rcar_cmm_config {
> + struct {
> + bool enable;
> + struct drm_color_lut *table;
As enable == true implies table != NULL, and enable == false implies
table == NULL, could we drop the enable field ?
With those small issues addressed,
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> + } lut;
> +};
> +
> +#if IS_ENABLED(CONFIG_DRM_RCAR_CMM)
> +int rcar_cmm_init(struct platform_device *pdev);
> +
> +int rcar_cmm_enable(struct platform_device *pdev);
> +void rcar_cmm_disable(struct platform_device *pdev);
> +
> +int rcar_cmm_setup(struct platform_device *pdev,
> + const struct rcar_cmm_config *config);
> +#else
> +static inline int rcar_cmm_init(struct platform_device *pdev)
> +{
> + return -ENODEV;
> +}
> +
> +static inline int rcar_cmm_enable(struct platform_device *pdev)
> +{
> + return 0;
> +}
> +
> +static inline void rcar_cmm_disable(struct platform_device *pdev)
> +{
> +}
> +
> +static inline int rcar_cmm_setup(struct platform_device *pdev,
> + const struct rcar_cmm_config *config)
> +{
> + return 0;
> +}
> +#endif /* IS_ENABLED(CONFIG_DRM_RCAR_CMM) */
> +
> +#endif /* __RCAR_CMM_H__ */
--
Regards,
Laurent Pinchart