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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Aug 10, 2016 at 06:57:02PM +0200, Daniel Vetter wrote:
> On Wed, Aug 10, 2016 at 5:26 PM, Fabien DESSENNE <fabien.dessenne@st.com> wrote:
> > 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@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).
> 
> I've dug around and the only places I've found changes is from 2012. I
> think rgb444 formats just plain never worked. But in case I've missed
> something and this is a regression then indeed we need to fix it.

Looks like I just plain forgot about these formats when I added
drm_format_plane_cpp().

> For
> the real solution it's better to sync up with Laurent and his plans to
> rework the fourcc handling we have in drm.
> -Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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-- 
Ville Syrjälä
Intel OTC
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