Re: [Intel-gfx] [PATCH] drm/i915/pcode: Wait 10 seconds for pcode to settle

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 11 Jan 2023, Andi Shyti <andi.shyti@linux.intel.com> wrote:
> From: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
>
> During module load not all the punit transaction have completed
> and we might end up timing out, as shown by the following
> warning:

Root cause?

>
>    i915 0000:4d:00.0: drm_WARN_ON_ONCE(timeout_base_ms > 3)
>
> Wait 10 seconds for the punit to settle and complete any
> outstanding transactions upon module load.
>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/7814
>

No blank lines between the tag lines please.

> Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
> Co-developed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pcode.c | 35 ++++++++++++++++++++++++++----
>  1 file changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pcode.c b/drivers/gpu/drm/i915/intel_pcode.c
> index a234d9b4ed14..3db2ba439bb5 100644
> --- a/drivers/gpu/drm/i915/intel_pcode.c
> +++ b/drivers/gpu/drm/i915/intel_pcode.c
> @@ -204,15 +204,42 @@ int skl_pcode_request(struct intel_uncore *uncore, u32 mbox, u32 request,
>  #undef COND
>  }
>  
> +static int pcode_init_wait(struct intel_uncore *uncore, int timeout_ms)
> +{
> +	if (__intel_wait_for_register_fw(uncore,
> +					 GEN6_PCODE_MAILBOX,
> +					 GEN6_PCODE_READY, 0,
> +					 500, timeout_ms,
> +					 NULL))
> +		return -EPROBE_DEFER;

This is already done within skl_pcode_request -> skl_pcode_try_request
-> __snb_pcode_rw path, with waits in skl_pcode_request.

Is there anyone who still understands what's being waited for, where,
for how long, and why in the different code paths? I know I don't, and
this isn't helping.

There's also no explanation on the -EPROBE_DEFER return in the commit
message or comments or anywhere.

Again, root cause?

BR,
Jani.


> +
> +	return skl_pcode_request(uncore,
> +				 DG1_PCODE_STATUS,
> +				 DG1_UNCORE_GET_INIT_STATUS,
> +				 DG1_UNCORE_INIT_STATUS_COMPLETE,
> +				 DG1_UNCORE_INIT_STATUS_COMPLETE, timeout_ms);
> +}
> +
>  int intel_pcode_init(struct intel_uncore *uncore)
>  {
> +	int err;
> +
>  	if (!IS_DGFX(uncore->i915))
>  		return 0;
>  
> -	return skl_pcode_request(uncore, DG1_PCODE_STATUS,
> -				 DG1_UNCORE_GET_INIT_STATUS,
> -				 DG1_UNCORE_INIT_STATUS_COMPLETE,
> -				 DG1_UNCORE_INIT_STATUS_COMPLETE, 180000);
> +	/*
> +	 * Wait 10 seconds so that the punit to settle and complete
> +	 * any outstanding transactions upon module load
> +	 */
> +	err = pcode_init_wait(uncore, 10000);
> +
> +	if (err) {
> +		drm_notice(&uncore->i915->drm,
> +			   "Waiting for HW initialisation...\n");
> +		err = pcode_init_wait(uncore, 180000);
> +	}
> +
> +	return err;
>  }
>  
>  int snb_pcode_read_p(struct intel_uncore *uncore, u32 mbcmd, u32 p1, u32 p2, u32 *val)

-- 
Jani Nikula, Intel Open Source Graphics Center