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Date:   Mon, 2 May 2022 21:36:49 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Javier Martinez Canillas <javierm@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        dri-devel@lists.freedesktop.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v2 1/3] drm: Remove superfluous arg when calling to
 drm_fbdev_generic_setup()
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 <5dd80287-1b09-d02c-9f67-5a0bb0a4566c@redhat.com>
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On Mon, May 02, 2022 at 07:15:16PM +0200, Javier Martinez Canillas wrote:
> On 5/2/22 18:55, Javier Martinez Canillas wrote:
> 
> [snip]
> 
> >> drop the depth option to drm_fbdev_generic_setup() ? There's a FIXME
> >> comment in drm_fbdev_generic_setup() that could be related.
> > 
> > A FIXME makes sense, I'll add that to when posting a v3.
> 
> There's actually a FIXME already in drm_fbdev_generic_setup(), so it's
> a documented issue [0]:

That's what I meant by "there's a FIXME" :-) It doesn't have to be
addressed by this series, but it would be good to fix it.

> void drm_fbdev_generic_setup(struct drm_device *dev,
> 			     unsigned int preferred_bpp)
> {
> ...
> 	/*
> 	 * FIXME: This mixes up depth with bpp, which results in a glorious
> 	 * mess, resulting in some drivers picking wrong fbdev defaults and
> 	 * others wrong preferred_depth defaults.
> 	 */
> 	if (!preferred_bpp)
> 		preferred_bpp = dev->mode_config.preferred_depth;
> 	if (!preferred_bpp)
> 		preferred_bpp = 32;
> 	fb_helper->preferred_bpp = preferred_bpp;
> ...
> }
> 
> [0]: https://elixir.bootlin.com/linux/v5.18-rc5/source/drivers/gpu/drm/drm_fb_helper.c#L2553

-- 
Regards,

Laurent Pinchart