Hi Ivaylo, On 19/01/2022 12:23, Ivaylo Dimitrov wrote:
This patch series fixes excessive DMM or CMA usage of GEM buffers leading to various runtime allocation failures. The series enables daily usage of devices without exausting limited resources like CMA or DMM space if GPU rendering is needed. The first patch doesn't bring any functional changes, it just moves some TILER/DMM related code to a separate function, to simplify the review of the next two patches. The second patch allows off-CPU rendering to non-scanout buffers. Without that patch, it is basically impossible to use the driver allocated GEM buffers on OMAP3 for anything else but a basic CPU rendered examples as if we want GPU rendering, we must allocate buffers as scanout buffers, which are CMA allocated. CMA soon gets fragmented and we start seeing allocation failures. Such failres in Xorg cannot be handeled gracefully, so the system is basically unusable. Third patch fixes similar issue on OMAP4/5, where DMM/TILER spaces get fragmented with time, leading to allocation failures.
I think this is just hacking around the problem. The problem is that omapdrm is being used by some as a generic buffer allocator. Those users should be changed to use a their own allocator or a generic allocator. And we could then drop the OMAP_BO_SCANOUT flag, as all buffers would be scanout buffers.
Or do we have a regression in the driver? My understanding is that this has never really worked.
Tomi
