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List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On 7/10/24 04:43, Daniel Vetter wrote: > On Tue, Jul 09, 2024 at 10:02:08AM -0400, Hamza Mahfooz wrote: >> On 7/9/24 06:09, Daniel Vetter wrote: >>> On Tue, Jul 09, 2024 at 11:32:11AM +0200, Daniel Vetter wrote: >>>> On Mon, Jul 08, 2024 at 04:29:07PM -0400, Hamza Mahfooz wrote: >>>>> Hook up drm_crtc_set_vblank_offdelay() in amdgpu_dm, so that we can >>>>> enable PSR more quickly for displays that support it. >>>>> >>>>> Signed-off-by: Hamza Mahfooz >>>>> --- >>>>> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 30 ++++++++++++++----- >>>>> 1 file changed, 22 insertions(+), 8 deletions(-) >>>>> >>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c >>>>> index fdbc9b57a23d..ee6c31e9d3c4 100644 >>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c >>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c >>>>> @@ -8231,7 +8231,7 @@ static int amdgpu_dm_encoder_init(struct drm_device *dev, >>>>> static void manage_dm_interrupts(struct amdgpu_device *adev, >>>>> struct amdgpu_crtc *acrtc, >>>>> - bool enable) >>>>> + struct dm_crtc_state *acrtc_state) >>>>> { >>>>> /* >>>>> * We have no guarantee that the frontend index maps to the same >>>>> @@ -8239,12 +8239,25 @@ static void manage_dm_interrupts(struct amdgpu_device *adev, >>>>> * >>>>> * TODO: Use a different interrupt or check DC itself for the mapping. >>>>> */ >>>>> - int irq_type = >>>>> - amdgpu_display_crtc_idx_to_irq_type( >>>>> - adev, >>>>> - acrtc->crtc_id); >>>>> + int irq_type = amdgpu_display_crtc_idx_to_irq_type(adev, >>>>> + acrtc->crtc_id); >>>>> + struct dc_crtc_timing *timing; >>>>> + int offdelay; >>>>> + >>>>> + if (acrtc_state) { >>>>> + timing = &acrtc_state->stream->timing; >>>>> + >>>>> + /* at least 2 frames */ >>>>> + offdelay = 2000 / div64_u64(div64_u64((timing->pix_clk_100hz * >>>>> + (uint64_t)100), >>>>> + timing->v_total), >>>>> + timing->h_total) + 1; >>>> >>>> Yeah, _especially_ when you have a this short timeout your really have to >>>> instead fix the vblank driver code properly so you can enable >>>> vblank_disable_immediate. This is just cheating :-) >>> >>> Michel mentioned on irc that DC had immediate vblank disabling, but this >>> was reverted with f64e6e0b6afe ("Revert "drm/amdgpu/display: set >>> vblank_disable_immediate for DC""). >>> >>> I haven't looked at the details of the bug report, but stuttering is >>> exactly what happens when the driver's vblank code has these races. Going >>> for a very low timeout instead of zero just means it's a bit harder to hit >>> the issue, and much, much harder to debug properly. >>> >>> So yeah even more reasons to look at the underlying root-cause here I >>> think. >>> -Sima >> >> The issue is that DMUB (display firmware) isn't able to keep up with all of >> the requests that the driver is making. The issue is fairly difficult to >> reproduce (I've only seen it once after letting the system run with a >> program that would engage PSR every so often, after several hours). >> It is also worth noting that we have the same 2 idle frame wait on the >> windows >> driver, for the same reasons. So, in all likelihood if it is your opinion >> that >> the series should be NAKed, we will probably have to move the wait into the >> driver as a workaround. > > Well that's an entirely different reason, and needs to be recorded in the > commit log that disabling/enabling vblank is too expensive and why. Also > would be good to record that windows does the same. Point taken. > > I'm also not entirely sure this is a good interface, so some > thoughts/question: > > - is the issue only with psr, meaning that if we switch the panel to a > different crtc, do we need to update the off delay. I can't say definitively, but all of the public reports (that I've seen) and my local repro are PSR related. > > - there's still the question of why vblank_immediate_disable resulted in > stuttering, is that the same bug? I think for consistency it'd be best > if we enable immediate vblank disabling everywhere (for maximum > testing), and then apply the 2 frame delay workaround only where needed > explicitly. Otherwise if there's other issues than DMUB being slow, they > might be mostly hidden and become really hard to track down when they > show up. Ya, I believe they are all DMUB related since the stuttering issues are accompanied by the following dmesg log entry: [drm:dc_dmub_srv_wait_idle [amdgpu]] *ERROR* Error waiting for DMUB idle: status=3 (which is pretty much an unspecified firmware timeout) Also, setting vblank_immediate_disable unconditionally for amdgpu, while only enabling the delay for cases that we know that we need it seems reasonable to me. > > - I think an interface to set the right values in lockstep with the vblank > on/off state would be best, so maybe a special drm_crtc_vblank_on_config > that takes additional parameters? Sure, that seems fine, what parameters besides the off delay did you have in mind though? > > Cheers, Sima -- Hamza