[PATCH] [RFC] drm/etnaviv: Disable softpin

[Lucas Stach]

Am Freitag, dem 02.12.2022 um 00:21 +0100 schrieb Marek Vasut:
> Currently softpin suffers from assorted race conditions exposed by newer
> versions of mesa 22.2.y and 22.3.y . Those races are difficult to fix in
> older kernel versions due to massive amount of backports necessary to do
> so. Disable softpin by default until Linux 6.1.y is out, which contains
> the necessary fixes to make softpin work reliably.
> 
Sorry, but that's a NACK. The userspace driver depends on softpin for
GPUs with texture descriptors, so this introduces a hard functional
regression for those GPUs. I.e. they would go from "require race fixes
that are already on the way to upstream" to not working at all.

Regards,
Lucas

> Fixes: 088880ddc0b20 ("drm/etnaviv: implement softpin")
> Signed-off-by: Marek Vasut <marex at denx.de>
> ---
> Cc: Christian Gmeiner <christian.gmeiner at gmail.com>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: David Airlie <airlied at linux.ie>
> Cc: Lucas Stach <l.stach at pengutronix.de>
> Cc: Russell King <linux+etnaviv at armlinux.org.uk>
> Cc: etnaviv at lists.freedesktop.org
> To: dri-devel at lists.freedesktop.org
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> index 51320eeebfcff..326c9696cccea 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -146,10 +146,7 @@ int etnaviv_gpu_get_param(struct etnaviv_gpu *gpu, u32 param, u64 *value)
>  		break;
>  
>  	case ETNAVIV_PARAM_SOFTPIN_START_ADDR:
> -		if (priv->mmu_global->version == ETNAVIV_IOMMU_V2)
> -			*value = ETNAVIV_SOFTPIN_START_ADDRESS;
> -		else
> -			*value = ~0ULL;
> +		*value = ~0ULL;
>  		break;
>  
>  	case ETNAVIV_PARAM_GPU_PRODUCT_ID: