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Date:   Thu, 17 Feb 2022 21:34:36 +0100
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Thomas Zimmermann <tzimmermann@suse.de>,
        Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
        David Airlie <airlied@linux.ie>, Helge Deller <deller@gmx.de>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux/m68k <linux-m68k@vger.kernel.org>,
        DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 2/8] drm/fb-helper: Add support for DRM_FORMAT_C[124]
Message-ID: <Yg6xXFouzq/4YCgU@ravnborg.org>
References: <20220215165226.2738568-1-geert@linux-m68k.org>
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 <4fff0c08-adab-c1d5-4a7e-1513cb2bf7ca@suse.de>
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Hi Geert,

> > > +     switch (fb->format->depth) {
> >
> > The depth field is deprecated. It's probably better to use
> > fb->format->format and test against 4CC codes.
> 
> The reason I checked for depth instead of a 4CC code is that the only
> thing that matters here is the number of bits per pixel.  Hence this
> function won't need any changes to support R1, R2, R4, and D1 later.
> When we get here, we already know that we are using a format that
> is supported by the fbdev helper code, and thus passed the 4CC
> checks elsewhere.
> 
> Alternatively, we could introduce drm_format_info_bpp() earlier in
> the series, and use that?

The drm_format_info_bpp() is very descriptive, so yes it would be good to use
it here also.

	Sam