On Mon, Jul 15, 2024 at 02:00:10PM -0700, Rob Clark wrote: > On Thu, Jul 11, 2024 at 3:02 AM Vladimir Lypak <vladimir.lypak@xxxxxxxxx> wrote: > > > > Fine grain preemption (switching from/to points within submits) > > requires extra handling in command stream of those submits, especially > > when rendering with tiling (using GMEM). However this handling is > > missing at this point in mesa (and always was). For this reason we get > > random GPU faults and hangs if more than one priority level is used > > because local preemption is enabled prior to executing command stream > > from submit. > > With that said it was ahead of time to enable local preemption by > > default considering the fact that even on downstream kernel it is only > > enabled if requested via UAPI. > > > > Fixes: a7a4c19c36de ("drm/msm/a5xx: fix setting of the CP_PREEMPT_ENABLE_LOCAL register") > > Signed-off-by: Vladimir Lypak <vladimir.lypak@xxxxxxxxx> > > --- > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c > > index c0b5373e90d7..6c80d3003966 100644 > > --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c > > +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c > > @@ -150,9 +150,13 @@ static void a5xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit) > > OUT_PKT7(ring, CP_SET_PROTECTED_MODE, 1); > > OUT_RING(ring, 1); > > > > - /* Enable local preemption for finegrain preemption */ > > + /* > > + * Disable local preemption by default because it requires > > + * user-space to be aware of it and provide additional handling > > + * to restore rendering state or do various flushes on switch. > > + */ > > OUT_PKT7(ring, CP_PREEMPT_ENABLE_LOCAL, 1); > > - OUT_RING(ring, 0x1); > > + OUT_RING(ring, 0x0); > > From a quick look at the a530 pfp fw, it looks like > CP_PREEMPT_ENABLE_LOCAL is allowed in IB1/IB2 (ie. not restricted to > kernel RB). So we should just disable it in the kernel, and let > userspace send a CP_PREEMPT_ENABLE_LOCAL to enable local preemption. Ack. AFAIU about a5x preemption, this should work. -Akhil > > BR, > -R > > > /* Allow CP_CONTEXT_SWITCH_YIELD packets in the IB2 */ > > OUT_PKT7(ring, CP_YIELD_ENABLE, 1); > > -- > > 2.45.2 > >