linux-kernel - Re: [PATCH 01/19] drm/fourcc: Add a function to tell if the format embeds alpha

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Message-ID: <20180116201724.lyhnsxfik532lzcq@flea.lan>
Date:   Tue, 16 Jan 2018 21:17:24 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Ayan Halder <ayan.halder@....com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        linux-kernel@...r.kernel.org,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chen-Yu Tsai <wens@...e.org>, dri-devel@...ts.freedesktop.org,
        Daniel Vetter <daniel.vetter@...el.com>, thomas@...sch.nl,
        linux-arm-kernel@...ts.infradead.org,
        Mark Yao <mark.yao@...k-chips.com>
Subject: Re: [PATCH 01/19] drm/fourcc: Add a function to tell if the format
 embeds alpha

Hi Ayan,

On Mon, Jan 15, 2018 at 03:47:44PM +0000, Ayan Halder wrote:
> On Tue, Jan 09, 2018 at 02:28:33PM +0100, Maxime Ripard wrote:
> > On Tue, Jan 09, 2018 at 02:29:58PM +0200, Laurent Pinchart wrote:
> > > On Tuesday, 9 January 2018 12:56:20 EET Maxime Ripard wrote:
> > > > There's a bunch of drivers that duplicate the same function to know if a
> > > > particular format embeds an alpha component or not.
> > > >
> > > > Let's create a helper to avoid duplicating that logic.
> > > >
> > > > Cc: Boris Brezillon <boris.brezillon@...e-electrons.com>
> > > > Cc: Eric Anholt <eric@...olt.net>
> > > > Cc: Inki Dae <inki.dae@...sung.com>
> > > > Cc: Joonyoung Shim <jy0922.shim@...sung.com>
> > > > Cc: Kyungmin Park <kyungmin.park@...sung.com>
> > > > Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > > > Cc: Mark Yao <mark.yao@...k-chips.com>
> > > > Cc: Seung-Woo Kim <sw0312.kim@...sung.com>
> > > > Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> > > > ---
> > > >  drivers/gpu/drm/drm_fourcc.c | 43 +++++++++++++++++++++++++++++++++++++-
> > > >  include/drm/drm_fourcc.h     |  1 +-
> > > >  2 files changed, 44 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> > > > index 9c0152df45ad..6e6227d6a46b 100644
> > > > --- a/drivers/gpu/drm/drm_fourcc.c
> > > > +++ b/drivers/gpu/drm/drm_fourcc.c
> > > > @@ -348,3 +348,46 @@ int drm_format_plane_height(int height, uint32_t
> > > > format, int plane) return height / info->vsub;
> > > >  }
> > > >  EXPORT_SYMBOL(drm_format_plane_height);
> > > > +
> > > > +/**
> > > > + * drm_format_has_alpha - get whether the format embeds an alpha component
> > > > + * @format: pixel format (DRM_FORMAT_*)
> > > > + *
> > > > + * Returns:
> > > > + * true if the format embeds an alpha component, false otherwise.
> > > > + */
> > > > +bool drm_format_has_alpha(uint32_t format)
> > > > +{
> > > > + switch (format) {
> > > > + case DRM_FORMAT_ARGB4444:
> > > > + case DRM_FORMAT_ABGR4444:
> > > > + case DRM_FORMAT_RGBA4444:
> > > > + case DRM_FORMAT_BGRA4444:
> > > > + case DRM_FORMAT_ARGB1555:
> > > > + case DRM_FORMAT_ABGR1555:
> > > > + case DRM_FORMAT_RGBA5551:
> > > > + case DRM_FORMAT_BGRA5551:
> > > > + case DRM_FORMAT_ARGB8888:
> > > > + case DRM_FORMAT_ABGR8888:
> > > > + case DRM_FORMAT_RGBA8888:
> > > > + case DRM_FORMAT_BGRA8888:
> > > > + case DRM_FORMAT_ARGB2101010:
> > > > + case DRM_FORMAT_ABGR2101010:
> > > > + case DRM_FORMAT_RGBA1010102:
> > > > + case DRM_FORMAT_BGRA1010102:
> > > > + case DRM_FORMAT_AYUV:
> > > > + case DRM_FORMAT_XRGB8888_A8:
> > > > + case DRM_FORMAT_XBGR8888_A8:
> > > > + case DRM_FORMAT_RGBX8888_A8:
> > > > + case DRM_FORMAT_BGRX8888_A8:
> > > > + case DRM_FORMAT_RGB888_A8:
> > > > + case DRM_FORMAT_BGR888_A8:
> > > > + case DRM_FORMAT_RGB565_A8:
> > > > + case DRM_FORMAT_BGR565_A8:
> > > > +         return true;
> > > > +
> > > > + default:
> > > > +         return false;
> > > > + }
> > > > +}
> > > > +EXPORT_SYMBOL(drm_format_has_alpha);
> > >
> > > How about adding the information to struct drm_format_info instead ?
> > > drm_format_has_alpha() could then be implemented as
> > >
> > > bool drm_format_has_alpha(uint32_t format)
> > > {
> > >     const struct drm_format_info *info;
> > >
> > >     info = drm_format_info(format);
> > >     return info ? info->has_alpha : false;
> > > }
> >
> > I considered it, and wasn't too sure about if adding more fields to
> > drm_format_info was ok. I can definitely do it that way.
>
> Are you going to send an updated patch with the change mentioned here.
> Or should I update my patch (https://patchwork.kernel.org/patch/10161023/)
> and change the type of '.alpha' to boolean to denote if the color
> format has an alpha channel or not.

Yes, I already had those patches ready. I'm just waiting for the
discussion on the alpha property to settle before sending a v2.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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