[PATCH v2] drm/etnaviv: fix external abort seen on GC600 rev 0x19

[Ing. Josua Mayer]

Verified that it works as intended on 5.7.10. Thank you very much :)
Feel free to add my tested-by ...

Am 23.08.20 um 21:09 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_ECO_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 at gmail.com>
> Reported-by: Josua Mayer <josua.mayer at jm0.eu>
> Fixes: 815e45bbd4d3 ("drm/etnaviv: determine product, customer and eco id")
> Cc: stable at vger.kernel.org
> ---
> Changelog:
> 
> V2:
>  - use correct register for conditional reads.
> 
> ---
>  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..c6404b8d067f 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -337,9 +337,16 @@ 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.eco_id = gpu_read(gpu, VIVS_HI_CHIP_ECO_ID);
> +		}
>  
>  		/*
>  		 * !!!! HACK ALERT !!!!
>