[PATCH] drm: Set depth and bpp for XRGB4444 family formats

[Fabien DESSENNE]

On 08/10/2016 04:12 PM, Daniel Vetter wrote:
> On Wed, Aug 10, 2016 at 01:04:54PM +0200, Fabien DESSENNE wrote:
>> On 08/10/2016 12:35 PM, Daniel Vetter wrote:
>>> On Wed, Aug 10, 2016 at 11:21:56AM +0200, Fabien Dessenne wrote:
>>>> These pixel formats are supported by format_check() from drm_crtc.c, so
>>>> provide there depth and bpp.
>>>>
>>>> Signed-off-by: Fabien Dessenne <fabien.dessenne at st.com>
>>> Why?
>> At least for consistency between format_check() and drm_fb_get_bpp_depth().
> fb_get_bpp_depth is kinda legacy, the recommended way is to have a switch
> statement in your driver that directly decodes DRM_FORMAT_* into driver
> register values. The inconsistency is intentional since just looking at
> bpp and depth removes a lot of information.
I can understand  that fb_get_bpp_depth() shall not be called by (new) 
drivers.
But it is also called by the core part through drm_format_plane_cpp() 
which is not a legacy interface and is used across many drivers (I think 
that this is a recent change initiated by Ville).
> Probably a better patch would be to update the kerneldoc for these
> functions.

For the time being we have an issue with the current drivers that use 
the 4444 DRM formats and updating kerneldoc won't fix them
>   Also Laurent is working on a complete reorg of all this.

Looping Laurent who may have a different opinion, or plan to consider 
the 4444 DRM formats in its rework.

Fabien
> -Daniel
>
>>> Who's going to use this?
>> For the time being, I can see 9 drivers that make more or less use of
>> this format (amd, atmel-hlcdc, exynos, fsl-dcu, imx, omapdrm, radeon,
>> rcar-du, sti).
>> In top of that I am working on a new driver that actually needs this
>> format, and that does not work without this patch.
>>> -Daniel
>>>
>>>> ---
>>>>    drivers/gpu/drm/drm_fourcc.c | 11 +++++++++++
>>>>    1 file changed, 11 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
>>>> index 0645c85..aa8c909 100644
>>>> --- a/drivers/gpu/drm/drm_fourcc.c
>>>> +++ b/drivers/gpu/drm/drm_fourcc.c
>>>> @@ -80,6 +80,17 @@ void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
>>>>    		*depth = 8;
>>>>    		*bpp = 8;
>>>>    		break;
>>>> +	case DRM_FORMAT_XRGB4444:
>>>> +	case DRM_FORMAT_XBGR4444:
>>>> +	case DRM_FORMAT_RGBX4444:
>>>> +	case DRM_FORMAT_BGRX4444:
>>>> +	case DRM_FORMAT_ARGB4444:
>>>> +	case DRM_FORMAT_ABGR4444:
>>>> +	case DRM_FORMAT_RGBA4444:
>>>> +	case DRM_FORMAT_BGRA4444:
>>>> +		*depth = 12;
>>>> +		*bpp = 16;
>>>> +		break;
>>>>    	case DRM_FORMAT_XRGB1555:
>>>>    	case DRM_FORMAT_XBGR1555:
>>>>    	case DRM_FORMAT_RGBX5551:
>>>> -- 
>>>> 1.9.1
>>>>
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