linux-kernel - Re: [PATCH v2] drm/panfrost:report the full raw fault information instead

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Date:   Fri, 2 Jul 2021 09:40:23 +0800
From:   Chunyou Tang <tangchunyou@....com>
To:     Steven Price <steven.price@....com>
Cc:     tomeu.vizoso@...labora.com, airlied@...ux.ie,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        alyssa.rosenzweig@...labora.com,
        ChunyouTang <tangchunyou@...becorp.cn>
Subject: Re: [PATCH v2] drm/panfrost:report the full raw fault information
 instead

Hi Steve,
> You didn't answer my previous question:
> 
> > Is this device working with the kbase/DDK proprietary driver?

I don't know whether I used kbase/DDK,I only know I used the driver of
panfrost in linux 5.11.

> What you are describing sounds like a hardware integration issue, so
> it would be good to check that the hardware is working with the
> proprietary driver to rule that out. And perhaps there is something
> in the kbase for this device that is setting a chicken bit to 'fix'
> the coherency?

I don't have the proprietary driver,I only used driver in linux 5.11.

Thinks very much!

Chunyou.


于 Thu, 1 Jul 2021 11:15:14 +0100
Steven Price <steven.price@....com> 写道:

> On 29/06/2021 04:04, Chunyou Tang wrote:


> > Hi Steve,
> > 	thinks for your reply.
> > 	I set the pte in arm_lpae_prot_to_pte(),
> > ***********************************************************************
> > 	/*
> > 	 * Also Mali has its own notions of shareability wherein its
> > Inner
> > 	 * domain covers the cores within the GPU, and its Outer
> > domain is
> > 	 * "outside the GPU" (i.e. either the Inner or System
> > domain in CPU
> > 	 * terms, depending on coherency).
> > 	 */
> > 	if (prot & IOMMU_CACHE && data->iop.fmt != ARM_MALI_LPAE)
> > 		pte |= ARM_LPAE_PTE_SH_IS;
> > 	else
> > 		pte |= ARM_LPAE_PTE_SH_OS;
> > ***********************************************************************
> > I set pte |= ARM_LPAE_PTE_SH_NS.
> > 
> > 	If I set pte to ARM_LPAE_PTE_SH_OS or
> > 	ARM_LPAE_PTE_SH_IS,whether I use singel core GPU or multi
> > core GPU,it will occur GPU Fault.
> > 	if I set pte to ARM_LPAE_PTE_SH_NS,whether I use singel core
> > 	GPU or multi core GPU,it will not occur GPU Fault.
> 
> Hi,
> 
> So this is a difference between Panfrost and kbase. Panfrost (well
> technically the IOMMU framework) enables the inner-shareable bit for
> all memory, whereas kbase only enables it for some memory types (the
> BASE_MEM_COHERENT_LOCAL flag in the UABI controls it). However this
> should only be a performance/power difference (and AFAIK probably an
> irrelevant one) and it's definitely required that "inner shareable"
> (i.e. within the GPU) works for communication between the different
> units of the GPU.
> 
> You didn't answer my previous question:
> 
> > Is this device working with the kbase/DDK proprietary driver?
> 
> What you are describing sounds like a hardware integration issue, so
> it would be good to check that the hardware is working with the
> proprietary driver to rule that out. And perhaps there is something
> in the kbase for this device that is setting a chicken bit to 'fix'
> the coherency?
> 
> Steve