Re: [PATCH v2 31/43] drm/sun4i: Add a dedicated ioctl call for allocating tiled buffers

[Brian Starkey]

Hi Paul,

On Fri, Nov 23, 2018 at 10:25:03AM +0100, Paul Kocialkowski wrote:
>This introduces a dedicated ioctl for allocating buffers for the VPU
>tiling mode. It allows setting up buffers that comply to the hardware
>alignment requirements, by aligning the stride and height to 32 bytes.
>
>Only YUV semiplanar and planar formats are allowed by the ioctl, as the
>hardware does not support the tiling mode for other formats.

What's the general feeling about a more generic version of this ioctl?
There doesn't seem to be anything Allwinner-specific in the ioctl
arguments.

It effectively boils down to:

	size = driver->get_fb_size_with_modifier(...);
 	cma_obj = drm_gem_cma_create(drm, size);

It would look exactly the same for Mali-DP, and probably others too.
Is it better to try and define something we can share instead of Arm
adding another nearly identical ioctl() later?

I think the minimal viable thing would be to just add modifiers to
your structure (I put them first because padding):

  struct drm_gem_create_with_modifiers {
  	__u64 modifiers[4];
  	__u32 height;
  	__u32 width;
  	__u32 format;
  	/* handle, offsets, pitches, size will be returned */
  	__u32 handle;
  	__u32 pitches[4];
  	__u32 offsets[4];
  	__u64 size;
  };

Thanks,
-Brian

>
>Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
>---
> drivers/gpu/drm/sun4i/sun4i_drv.c | 89 +++++++++++++++++++++++++++++++
> include/uapi/drm/sun4i_drm.h      | 42 +++++++++++++++
> 2 files changed, 131 insertions(+)
> create mode 100644 include/uapi/drm/sun4i_drm.h
>
>diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.c b/drivers/gpu/drm/sun4i/sun4i_drv.c
>index ccdeae6299eb..5ae32973cf34 100644
>--- a/drivers/gpu/drm/sun4i/sun4i_drv.c
>+++ b/drivers/gpu/drm/sun4i/sun4i_drv.c
>@@ -21,6 +21,7 @@
> #include <drm/drm_gem_cma_helper.h>
> #include <drm/drm_fb_helper.h>
> #include <drm/drm_of.h>
>+#include <drm/sun4i_drm.h>
>
> #include "sun4i_drv.h"
> #include "sun4i_frontend.h"
>@@ -28,6 +29,92 @@
> #include "sun4i_tcon.h"
> #include "sun8i_tcon_top.h"
>
>+int drm_sun4i_gem_create_tiled(struct drm_device *drm, void *data,
>+			       struct drm_file *file_priv)
>+{
>+	struct drm_sun4i_gem_create_tiled *args = data;
>+	struct drm_gem_cma_object *cma_obj;
>+	struct drm_gem_object *gem_obj;
>+	uint32_t luma_stride, chroma_stride;
>+	uint32_t luma_height, chroma_height;
>+	uint32_t chroma_width;
>+	const struct drm_format_info *info;
>+	int ret;
>+
>+	info = drm_format_info(args->format);
>+	if (!info)
>+		return -EINVAL;
>+
>+	/* The tiled output format only applies to non-packed YUV formats. */
>+	if (!info->is_yuv || info->num_planes == 1)
>+		return -EINVAL;
>+
>+	memset(args->pitches, 0, sizeof(args->pitches));
>+	memset(args->offsets, 0, sizeof(args->offsets));
>+
>+	/* Stride and height are aligned to 32 bytes for our tiled format. */
>+	luma_stride = ALIGN(args->width, 32);
>+	luma_height = ALIGN(args->height, 32);
>+
>+	chroma_width = args->width;
>+
>+	/* Semiplanar formats have both U and V data in their chroma plane. */
>+	if (drm_format_info_is_yuv_semiplanar(info))
>+		chroma_width *= 2;
>+
>+	chroma_stride = ALIGN(DIV_ROUND_UP(chroma_width, info->hsub), 32);
>+	chroma_height = ALIGN(DIV_ROUND_UP(args->height, info->vsub), 32);
>+
>+	if (drm_format_info_is_yuv_semiplanar(info)) {
>+		args->pitches[0] = luma_stride;
>+		args->pitches[1] = chroma_stride;
>+
>+		args->offsets[0] = 0;
>+		args->offsets[1] = luma_stride * luma_height;
>+
>+		args->size = luma_stride * luma_height +
>+			     chroma_stride * chroma_height;
>+	} else if (drm_format_info_is_yuv_planar(info)) {
>+		args->pitches[0] = luma_stride;
>+		args->pitches[1] = chroma_stride;
>+		args->pitches[2] = chroma_stride;
>+
>+		args->offsets[0] = 0;
>+		args->offsets[1] = luma_stride * luma_height;
>+		args->offsets[2] = luma_stride * luma_height +
>+				   chroma_stride * chroma_height;
>+
>+		args->size = luma_stride * luma_height +
>+			     chroma_stride * chroma_height * 2;
>+	} else {
>+		/* No support for other formats in tiled mode. */
>+		return -EINVAL;
>+	}
>+
>+	cma_obj = drm_gem_cma_create(drm, args->size);
>+	if (IS_ERR(cma_obj))
>+		return PTR_ERR(cma_obj);
>+
>+	gem_obj = &cma_obj->base;
>+
>+	/*
>+	 * allocate a id of idr table where the obj is registered
>+	 * and handle has the id what user can see.
>+	 */
>+	ret = drm_gem_handle_create(file_priv, gem_obj, &args->handle);
>+	/* drop reference from allocate - handle holds it now. */
>+	drm_gem_object_put_unlocked(gem_obj);
>+	if (ret)
>+		return ret;
>+
>+	return PTR_ERR_OR_ZERO(cma_obj);
>+}
>+
>+static const struct drm_ioctl_desc sun4i_drv_ioctls[] = {
>+	DRM_IOCTL_DEF_DRV(SUN4I_GEM_CREATE_TILED, drm_sun4i_gem_create_tiled,
>+			  DRM_UNLOCKED),
>+};
>+
> static int drm_sun4i_gem_dumb_create(struct drm_file *file_priv,
> 				     struct drm_device *drm,
> 				     struct drm_mode_create_dumb *args)
>@@ -44,6 +131,8 @@ static struct drm_driver sun4i_drv_driver = {
> 	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME | DRIVER_ATOMIC,
>
> 	/* Generic Operations */
>+	.ioctls			= sun4i_drv_ioctls,
>+	.num_ioctls		= ARRAY_SIZE(sun4i_drv_ioctls),
> 	.fops			= &sun4i_drv_fops,
> 	.name			= "sun4i-drm",
> 	.desc			= "Allwinner sun4i Display Engine",
>diff --git a/include/uapi/drm/sun4i_drm.h b/include/uapi/drm/sun4i_drm.h
>new file mode 100644
>index 000000000000..2c77584b057b
>--- /dev/null
>+++ b/include/uapi/drm/sun4i_drm.h
>@@ -0,0 +1,42 @@
>+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
>+/* sun4i_drm.h
>+ *
>+ * Copyright (C) 2018 Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
>+ *
>+ * This program is free software; you can redistribute  it and/or modify it
>+ * under  the terms of  the GNU General  Public License as published by the
>+ * Free Software Foundation;  either version 2 of the  License, or (at your
>+ * option) any later version.
>+ */
>+
>+#ifndef _UAPI_SUN4I_DRM_H_
>+#define _UAPI_SUN4I_DRM_H_
>+
>+#include "drm.h"
>+
>+#if defined(__cplusplus)
>+extern "C" {
>+#endif
>+
>+struct drm_sun4i_gem_create_tiled {
>+	__u32 height;
>+	__u32 width;
>+	__u32 format;
>+	/* handle, offsets, pitches, size will be returned */
>+	__u32 handle;
>+	__u32 pitches[4];
>+	__u32 offsets[4];
>+	__u64 size;
>+};
>+
>+#define DRM_SUN4I_GEM_CREATE_TILED	0x00
>+
>+#define DRM_IOCTL_SUN4I_GEM_CREATE_TILED \
>+	DRM_IOWR(DRM_COMMAND_BASE + DRM_SUN4I_GEM_CREATE_TILED, \
>+		 struct drm_sun4i_gem_create_tiled)
>+
>+#if defined(__cplusplus)
>+}
>+#endif
>+
>+#endif /* _UAPI_SUN4I_DRM_H_ */
>-- 
>2.19.1
>
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