Re: [PATCH v2 4/6] drm/etnaviv: Identify GPU already when binding

[Lucas Stach <l.stach@pengutronix.de>]

Am Mittwoch, dem 18.06.2025 um 22:43 +0200 schrieb Gert Wollny:
> This is required to know whether to be able to avoid allocating
> the flop reset data if non of the available GPUs actually need
> it.
> 
I'm surprised that this works on your platform at all. You can not move
the identification here, as the GPU is still treated as suspended in
etnaviv_gpu_bind, so on platforms with clock or power gating reading
the ID registers will cause aborts or system hangs.

Regards,
Lucas

> Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> index cf0d9049bcf1..dc8a7ff3e797 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -829,14 +829,6 @@ int etnaviv_gpu_init(struct etnaviv_gpu *gpu)
>  		goto fail;
>  	}
>  
> -	etnaviv_hw_identify(gpu);
> -
> -	if (gpu->identity.model == 0) {
> -		dev_err(gpu->dev, "Unknown GPU model\n");
> -		ret = -ENXIO;
> -		goto fail;
> -	}
> -
>  	if (gpu->identity.nn_core_count > 0)
>  		dev_warn(gpu->dev, "etnaviv has been instantiated on a NPU, "
>                                     "for which the UAPI is still experimental\n");
> @@ -1808,6 +1800,13 @@ static int etnaviv_gpu_bind(struct device *dev, struct device *master,
>  	INIT_WORK(&gpu->sync_point_work, sync_point_worker);
>  	init_waitqueue_head(&gpu->fence_event);
>  
> +	etnaviv_hw_identify(gpu);
> +
> +	if (gpu->identity.model == 0) {
> +		dev_err(gpu->dev, "Unknown GPU model\n");
> +		ret = -ENXIO;
> +		goto out_sched;
> +	}
>  	priv->gpu[priv->num_gpus++] = gpu;
>  
>  	return 0;