[PATCH] DRM/Radeon: Set depth on low mem Radeon cards to 16 instead of 8.

Egbert Eich eich at suse.com
Thu Oct 25 15:40:46 PDT 2012

Dave Airlie writes:
 > On Thu, Oct 25, 2012 at 3:07 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
 > > On Wed, Oct 24, 2012 at 12:33 PM, Egbert Eich <eich at suse.de> wrote:
 > >> The Radeon driver reduces the framebuffer resolution to 8bpp if
 > >> a device with less than 32 Mb VRAM is found. This causes the
 > >> framebuffer to run in 8 bit paletted mode. For a text console this
 > >> is not an issue as 256 different colors is more than one gets
 > >> on a VGA text console.
 > >> It is done to give X more memory to work with since the console memory
 > >> is not freed but remains allocated while X is active.
 > >> Still, running the fbdev Xserver driver - which we do during installation
 > >> - will give applications an 8bit pseudo-color visual which doesn't look
 > >> too pretty.
 > >> We therefore limit the framebuffer bpp to 16 when memory is 24MB or lower
 > >> and to 8 only if 8MB or less VRAM is found.
 > >> This should be a reasonable compromise for us.
 > >> This patch will most likely not ever make it upstream.
 > >>
 > >> This works around ugly modes on crappy IPMI cards using ES1000.
 > >
 > > I don't have a strong opinion either way on this one.
 > Why would you use fbdev? package -modesetting at least if not the real ATI DDX.

fbdev is good as a general fallback which works pretty much everywhere - even
if there's no KMS driver available in the kernel (in this case with vesa
I'm not pushing strongly for this patch making it into the mainline kernel,
I need to carry it around for our enterprise product for the time being.
It could well be that it can be tossed once we redesign things for SLE13.

But maybe you may want to repace the '<=' with a '<' so that the code 
matches the comment above ie. that one gets 8bpp only for 16MB and less
which would already help.


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