linux-kernel - Re: [PATCH] drm/etnaviv: fix external abort seen on GC600 rev 0x19

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Date:   Sun, 23 Aug 2020 16:27:03 +0200
From:   "Ing. Josua Mayer" <josua.mayer@....eu>
To:     Christian Gmeiner <christian.gmeiner@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, Lucas Stach <l.stach@...gutronix.de>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, etnaviv@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/etnaviv: fix external abort seen on GC600 rev 0x19

Hi Christian,

I have formally tested the patch with 5.7.10 - and it doesn't resolve
the issue - sadly :(

>From my testing, the reads on
VIVS_HI_CHIP_PRODUCT_ID
VIVS_HI_CHIP_ECO_ID
need to be conditional - while
VIVS_HI_CHIP_CUSTOMER_ID
seems to be okay.

br
josau Mayer

Am 21.08.20 um 20:17 schrieb Christian Gmeiner:
> It looks like that this GPU core triggers an abort when
> reading VIVS_HI_CHIP_PRODUCT_ID and/or VIVS_HI_CHIP_CUSTOMER_ID.
> 
> I looked at different versions of Vivante's kernel driver and did
> not found anything about this issue or what feature flag can be
> used. So go the simplest route and do not read these two registers
> on the affected GPU core.
> 
> Signed-off-by: Christian Gmeiner <christian.gmeiner@...il.com>
> Reported-by: Josua Mayer <josua.mayer@....eu>
> Fixes: 815e45bbd4d3 ("drm/etnaviv: determine product, customer and eco id")
> Cc: stable@...r.kernel.org
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> index d5a4cd85a0f6..d3906688c2b3 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -337,10 +337,17 @@ static void etnaviv_hw_identify(struct etnaviv_gpu *gpu)
>  
>  		gpu->identity.model = gpu_read(gpu, VIVS_HI_CHIP_MODEL);
>  		gpu->identity.revision = gpu_read(gpu, VIVS_HI_CHIP_REV);
> -		gpu->identity.product_id = gpu_read(gpu, VIVS_HI_CHIP_PRODUCT_ID);
> -		gpu->identity.customer_id = gpu_read(gpu, VIVS_HI_CHIP_CUSTOMER_ID);
>  		gpu->identity.eco_id = gpu_read(gpu, VIVS_HI_CHIP_ECO_ID);
>  
> +		/*
> +		 * Reading these two registers on GC600 rev 0x19 result in a
> +		 * unhandled fault: external abort on non-linefetch
> +		 */
> +		if (!etnaviv_is_model_rev(gpu, GC600, 0x19)) {
> +			gpu->identity.product_id = gpu_read(gpu, VIVS_HI_CHIP_PRODUCT_ID);
> +			gpu->identity.customer_id = gpu_read(gpu, VIVS_HI_CHIP_CUSTOMER_ID);
> +		}
> +
>  		/*
>  		 * !!!! HACK ALERT !!!!
>  		 * Because people change device IDs without letting software
>