On 12/04/2023 17:13, Javier Martinez Canillas wrote:
Jocelyn Falempe <jfale...@redhat.com> writes:

The bandwidth between system memory and VRAM is very limited
on G200.
So when using a 32bit framebuffer on system memory, convert it to 24bit
when copying the frame to the VRAM, this allows to go 33% faster.
Converting the format on the fly is negligible, even on low end CPU.

small benchmark on my Dell T310:
1280x1024 32bits: ~125ms to transfert a single frame.
1280x1024 24bits: ~95ms

Signed-off-by: Jocelyn Falempe <jfale...@redhat.com>
---

I assume that the alpha channel is unused on this display HW and is just
exposed to user-space to make the DRM driver more compatible ?

Yes, alpha channel is dropped by the hardware, and has no impact on the display. Most userspace now prefer 32bit framebuffer. I know Gnome/wayland default to 32bit, and probably other DE are doing the same.


If so, probably has to be mentioned in the changelog but other than that:

ok I will add this in the commit message.


Reviewed-by: Javier Martinez Canillas <javi...@redhat.com>


Thanks,

--

Jocelyn

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