Re: [PATCH v2 7/7] drm: rcar-du: Add new formats (2-10-10-10 ARGB, Y210)

[Hans Verkuil <hverkuil-cisco@xs4all.nl>]

On 20/12/2022 10:18, Laurent Pinchart wrote:
> Hello,
> 
> On Tue, Dec 20, 2022 at 10:01:04AM +0100, Hans Verkuil wrote:
>> On 19/12/2022 22:47, Laurent Pinchart wrote:
>>> Hi Tomi,
>>>
>>> (CC'ing Sakari and Hans)
>>>
>>> Thank you for the patch.
>>>
>>> On Mon, Dec 19, 2022 at 04:01:39PM +0200, Tomi Valkeinen wrote:
>>>> Add new pixel formats: RGBX1010102, RGBA1010102, ARGB2101010 and Y210.
>>>>
>>>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
>>>> ---
>>>>  drivers/gpu/drm/rcar-du/rcar_du_kms.c | 24 +++++++++++++
>>>>  drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 49 +++++++++++++++++++++++++--
>>>>  2 files changed, 71 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
>>>> index 8c2719efda2a..8ccabf5a30c4 100644
>>>> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
>>>> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
>>>> @@ -259,6 +259,24 @@ static const struct rcar_du_format_info rcar_du_format_infos[] = {
>>>>  		.bpp = 32,
>>>>  		.planes = 1,
>>>>  		.hsub = 1,
>>>> +	}, {
>>>> +		.fourcc = DRM_FORMAT_RGBX1010102,
>>>
>>> Ah, here the format makes sense.
>>>
>>>> +		.v4l2 = V4L2_PIX_FMT_XBGR2101010,
>>>
>>> But this is horrible :-( Could we use the same names as DRM for new
>>> formats, when there is no conflict with existing V4L2 formats ?
>>>
>>> Sakari, Hans, what do you think ? Please see patch 1/7 in the series for
>>> the format definitions.
>>
>> V4L2 describes pixel formats based on how they appear in memory from the
>> lowest to highest memory address.
>>
>> If I am not mistaken, DRM uses the CPU order. So that explains the difference
>> in naming. I don't think we should hide that difference. And V4L2 has been
>> quite consistent in following memory ordering in the naming (except possibly
>> for some of the really old pixelformats).
> 
> We depart from that rule with at least the following RGB formats:
> 
> V4L2_PIX_FMT_XBGR32
> V4L2_PIX_FMT_BGRX32
> V4L2_PIX_FMT_ABGR32
> V4L2_PIX_FMT_BGRA32
> 
> While the following formats follow the rule:
> 
> V4L2_PIX_FMT_RGB24
> V4L2_PIX_FMT_BGR24
> V4L2_PIX_FMT_XRGB32
> V4L2_PIX_FMT_RGBX32
> V4L2_PIX_FMT_RGBA32
> V4L2_PIX_FMT_ARGB32
> 
> For 16-bit RGB formats, we name them based on the order in a 16-bit word
> which is then stored in memory in little endian (except for the formats
> explicitly defined as big-endian):
> 
> #define V4L2_PIX_FMT_RGB444  v4l2_fourcc('R', '4', '4', '4') /* 16  xxxxrrrr ggggbbbb */
> #define V4L2_PIX_FMT_ARGB444 v4l2_fourcc('A', 'R', '1', '2') /* 16  aaaarrrr ggggbbbb */
> #define V4L2_PIX_FMT_XRGB444 v4l2_fourcc('X', 'R', '1', '2') /* 16  xxxxrrrr ggggbbbb */
> #define V4L2_PIX_FMT_RGBA444 v4l2_fourcc('R', 'A', '1', '2') /* 16  rrrrgggg bbbbaaaa */
> #define V4L2_PIX_FMT_RGBX444 v4l2_fourcc('R', 'X', '1', '2') /* 16  rrrrgggg bbbbxxxx */
> #define V4L2_PIX_FMT_ABGR444 v4l2_fourcc('A', 'B', '1', '2') /* 16  aaaabbbb ggggrrrr */
> #define V4L2_PIX_FMT_XBGR444 v4l2_fourcc('X', 'B', '1', '2') /* 16  xxxxbbbb ggggrrrr */
> #define V4L2_PIX_FMT_BGRA444 v4l2_fourcc('G', 'A', '1', '2') /* 16  bbbbgggg rrrraaaa */
> #define V4L2_PIX_FMT_BGRX444 v4l2_fourcc('B', 'X', '1', '2') /* 16  bbbbgggg rrrrxxxx */
> #define V4L2_PIX_FMT_RGB555  v4l2_fourcc('R', 'G', 'B', 'O') /* 16  RGB-5-5-5     */
> #define V4L2_PIX_FMT_ARGB555 v4l2_fourcc('A', 'R', '1', '5') /* 16  ARGB-1-5-5-5  */
> #define V4L2_PIX_FMT_XRGB555 v4l2_fourcc('X', 'R', '1', '5') /* 16  XRGB-1-5-5-5  */
> #define V4L2_PIX_FMT_RGBA555 v4l2_fourcc('R', 'A', '1', '5') /* 16  RGBA-5-5-5-1  */
> #define V4L2_PIX_FMT_RGBX555 v4l2_fourcc('R', 'X', '1', '5') /* 16  RGBX-5-5-5-1  */
> #define V4L2_PIX_FMT_ABGR555 v4l2_fourcc('A', 'B', '1', '5') /* 16  ABGR-1-5-5-5  */
> #define V4L2_PIX_FMT_XBGR555 v4l2_fourcc('X', 'B', '1', '5') /* 16  XBGR-1-5-5-5  */
> #define V4L2_PIX_FMT_BGRA555 v4l2_fourcc('B', 'A', '1', '5') /* 16  BGRA-5-5-5-1  */
> #define V4L2_PIX_FMT_BGRX555 v4l2_fourcc('B', 'X', '1', '5') /* 16  BGRX-5-5-5-1  */
> #define V4L2_PIX_FMT_RGB565  v4l2_fourcc('R', 'G', 'B', 'P') /* 16  RGB-5-6-5     */

Yes, these are all really old pixel formats :-)

> 
> I would thus argue that, at least for RGB formats, naming them based on
> the byte order in memory isn't such a clear cut rule. 
> 
>> Departing from that would be more of a hindrance than a help, IMHO.

Ideally we would unify the drm and v4l2 formats to new defines shared among
the two subsystems. I believe that was attempted some years back. In the end,
it was just decided to keep them separate, i.e. it wasn't worth the effort.

So unless someone wants to restart that idea, I think we should just stick to
what we have today, warts and all.

Regards,

	Hans

>>
>>>> +		.bpp = 32,
>>>> +		.planes = 1,
>>>> +		.hsub = 1,
>>>> +	}, {
>>>> +		.fourcc = DRM_FORMAT_RGBA1010102,
>>>> +		.v4l2 = V4L2_PIX_FMT_ABGR2101010,
>>>> +		.bpp = 32,
>>>> +		.planes = 1,
>>>> +		.hsub = 1,
>>>> +	}, {
>>>> +		.fourcc = DRM_FORMAT_ARGB2101010,
>>>> +		.v4l2 = V4L2_PIX_FMT_BGRA1010102,
>>>> +		.bpp = 32,
>>>> +		.planes = 1,
>>>> +		.hsub = 1,
>>>>  	}, {
>>>>  		.fourcc = DRM_FORMAT_YVYU,
>>>>  		.v4l2 = V4L2_PIX_FMT_YVYU,
>>>> @@ -307,6 +325,12 @@ static const struct rcar_du_format_info rcar_du_format_infos[] = {
>>>>  		.bpp = 24,
>>>>  		.planes = 3,
>>>>  		.hsub = 1,
>>>> +	}, {
>>>> +		.fourcc = DRM_FORMAT_Y210,
>>>> +		.v4l2 = V4L2_PIX_FMT_Y210,
>>>> +		.bpp = 32,
>>>> +		.planes = 1,
>>>> +		.hsub = 2,
>>>>  	},
>>>
>>> Any reason why you'd not adding Y212 support already ?
>>>
>>>>  };
>>>>  
>>>> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
>>>> index e465aef41585..6f3e109a4f80 100644
>>>> --- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
>>>> +++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
>>>> @@ -139,6 +139,42 @@ static const u32 rcar_du_vsp_formats[] = {
>>>>  	DRM_FORMAT_YVU444,
>>>>  };
>>>>  
>>>> +/*
>>>> + * Gen4 supports the same formats as above, and additionally 2-10-10-10 RGB
>>>> + * formats and Y210 format.
>>>> + */
>>>> +static const u32 rcar_du_vsp_formats_gen4[] = {
>>>> +	DRM_FORMAT_RGB332,
>>>> +	DRM_FORMAT_ARGB4444,
>>>> +	DRM_FORMAT_XRGB4444,
>>>> +	DRM_FORMAT_ARGB1555,
>>>> +	DRM_FORMAT_XRGB1555,
>>>> +	DRM_FORMAT_RGB565,
>>>> +	DRM_FORMAT_BGR888,
>>>> +	DRM_FORMAT_RGB888,
>>>> +	DRM_FORMAT_BGRA8888,
>>>> +	DRM_FORMAT_BGRX8888,
>>>> +	DRM_FORMAT_ARGB8888,
>>>> +	DRM_FORMAT_XRGB8888,
>>>> +	DRM_FORMAT_RGBX1010102,
>>>> +	DRM_FORMAT_RGBA1010102,
>>>> +	DRM_FORMAT_ARGB2101010,
>>>> +	DRM_FORMAT_UYVY,
>>>> +	DRM_FORMAT_YUYV,
>>>> +	DRM_FORMAT_YVYU,
>>>> +	DRM_FORMAT_NV12,
>>>> +	DRM_FORMAT_NV21,
>>>> +	DRM_FORMAT_NV16,
>>>> +	DRM_FORMAT_NV61,
>>>> +	DRM_FORMAT_YUV420,
>>>> +	DRM_FORMAT_YVU420,
>>>> +	DRM_FORMAT_YUV422,
>>>> +	DRM_FORMAT_YVU422,
>>>> +	DRM_FORMAT_YUV444,
>>>> +	DRM_FORMAT_YVU444,
>>>> +	DRM_FORMAT_Y210,
>>>> +};
>>>> +
>>>>  static void rcar_du_vsp_plane_setup(struct rcar_du_vsp_plane *plane)
>>>>  {
>>>>  	struct rcar_du_vsp_plane_state *state =
>>>> @@ -436,14 +472,23 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct device_node *np,
>>>>  					 ? DRM_PLANE_TYPE_PRIMARY
>>>>  					 : DRM_PLANE_TYPE_OVERLAY;
>>>>  		struct rcar_du_vsp_plane *plane = &vsp->planes[i];
>>>> +		unsigned int num_formats;
>>>> +		const u32 *formats;
>>>> +
>>>> +		if (rcdu->info->gen < 4) {
>>>> +			num_formats = ARRAY_SIZE(rcar_du_vsp_formats);
>>>> +			formats = rcar_du_vsp_formats;
>>>> +		} else {
>>>> +			num_formats = ARRAY_SIZE(rcar_du_vsp_formats_gen4);
>>>> +			formats = rcar_du_vsp_formats_gen4;
>>>> +		}
>>>>  
>>>>  		plane->vsp = vsp;
>>>>  		plane->index = i;
>>>>  
>>>>  		ret = drm_universal_plane_init(&rcdu->ddev, &plane->plane,
>>>>  					       crtcs, &rcar_du_vsp_plane_funcs,
>>>> -					       rcar_du_vsp_formats,
>>>> -					       ARRAY_SIZE(rcar_du_vsp_formats),
>>>> +					       formats, num_formats,
>>>>  					       NULL, type, NULL);
>>>>  		if (ret < 0)
>>>>  			return ret;
>>>
>>
>