[Mesa-dev] [PATCH mesa] vulkan/wsi_common_display: Return SURFACE_LOST for fatal DRM errors

[Keith Packard]

Jason Ekstrand <jason at jlekstrand.net> writes:

> Is this the same thing that happens on VT switch?  If so, we may want to
> return SURFACE_LOST for leases and OUT_OF_DATE for things running directly
> on the display.

No, on VT switch, my code currently sits in the driver and waits for the
VT to return. The errors here are unexpected and the driver doesn't
currently have any way to recover from them. This patch came from
reviewing the valid error returns from these functions with my broader
understanding of Vulkan and evaluating which error message most
accurately described the situation. SURFACE_LOST is more accurate than
OUT_OF_DATE as a DRM lease termination (the only "normal" cause of these
errors) definitely requires the application create a new surface.

If there were errors we knew how to handle, and the way to handle them
was to re-query the surface and re-create the swap chain, then we should
return OUT_OF_DATE.

On another note, I re-read the spec for vkAcquireXlibDisplayEXT when
looking at this and found that it explicitly calls out VT switch as a
case where the driver is supposed to return 'an appropriate error', but
I can't see an error which would be appropriate in this case --
DEVICE_LOST and SURFACE_LOST are both effectively fatal errors to the
application while OUT_OF_DATE requires the application to re-query the
surface and re-construct the swap chain. I guess we could have the
surface query block until the VT returns? Is that better than just
having the presentation block?

-- 
-keith
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