linux-kernel - Re: [PATCH v2] iommu/arm-smmu-qcom: Only enable stall on smmu-v2

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Message-ID: <CAF6AEGvDGtP_AAwDYnv5C3Bdg5dJk2muNUpT+yGYe8bn97OSwA@mail.gmail.com>
Date: Mon, 6 Jan 2025 12:59:38 -0800
From: Rob Clark <robdclark@...il.com>
To: Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc: iommu@...ts.linux.dev, linux-arm-msm@...r.kernel.org, 
	freedreno@...ts.freedesktop.org, Robin Murphy <robin.murphy@....com>, 
	Will Deacon <will@...nel.org>, Rob Clark <robdclark@...omium.org>, Joerg Roedel <joro@...tes.org>, 
	"moderated list:ARM SMMU DRIVERS" <linux-arm-kernel@...ts.infradead.org>, 
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] iommu/arm-smmu-qcom: Only enable stall on smmu-v2

On Mon, Jan 6, 2025 at 12:11 PM Akhil P Oommen <quic_akhilpo@...cinc.com> wrote:
>
> On 1/3/2025 1:00 AM, Akhil P Oommen wrote:
> > On 1/3/2025 12:02 AM, Rob Clark wrote:
> >> From: Rob Clark <robdclark@...omium.org>
> >>
> >> On mmu-500, stall-on-fault seems to stall all context banks, causing the
> >> GMU to misbehave.  So limit this feature to smmu-v2 for now.
> >>
> >> This fixes an issue with an older mesa bug taking outo the system
> >> because of GMU going off into the weeds.
> >>
> >> What we _think_ is happening is that, if the GPU generates 1000's of
> >> faults at ~once (which is something that GPUs can be good at), it can
> >> result in a sufficient number of stalled translations preventing other
> >> transactions from entering the same TBU.
> >>
> >> Signed-off-by: Rob Clark <robdclark@...omium.org>
> >
> > Reviewed-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> >
>
> Btw, if stall is not enabled, I think there is no point in capturing
> coredump from adreno pagefault handler. By the time we start coredump,
> gpu might have switched context.
>
> -Akhil.
>
> > -Akhil
> >