Re: [Intel-gfx] [PATCH 03/27] drm/i915/guc: Connect the number of guc_ids to debugfs

From: John Harrison <john.c.harrison@intel.com>
To: Matthew Brost <matthew.brost@intel.com>,
	<intel-gfx@lists.freedesktop.org>,
	<dri-devel@lists.freedesktop.org>
Cc: <daniel.vetter@ffwll.ch>, <tony.ye@intel.com>, <zhengguo.xu@intel.com>
Subject: Re: [Intel-gfx] [PATCH 03/27] drm/i915/guc: Connect the number of guc_ids to debugfs
Date: Thu, 9 Sep 2021 15:16:22 -0700	[thread overview]
Message-ID: <bc10d3be-2294-5fae-4055-999e61180015@intel.com> (raw)
In-Reply-To: <20210820224446.30620-4-matthew.brost@intel.com>

On 8/20/2021 15:44, Matthew Brost wrote:
> For testing purposes it may make sense to reduce the number of guc_ids
> available to be allocated. Add debugfs support for setting the number of
> guc_ids.
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
It 'may make sense'? Is there an actual IGT/selftest test that uses this 
and needs to in order to not take several hours to run or something? 
Seems wrong to be adding a debugfs interface for something that would 
only be used for testing by internal developers who can quite easy just 
edit a define in the code to simplify their testing.

John.

> ---
>   .../gpu/drm/i915/gt/uc/intel_guc_debugfs.c    | 31 +++++++++++++++++++
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c |  3 +-
>   2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_debugfs.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_debugfs.c
> index 887c8c8f35db..b88d343ee432 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_debugfs.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_debugfs.c
> @@ -71,12 +71,43 @@ static bool intel_eval_slpc_support(void *data)
>   	return intel_guc_slpc_is_used(guc);
>   }
>   
> +static int guc_num_id_get(void *data, u64 *val)
> +{
> +	struct intel_guc *guc = data;
> +
> +	if (!intel_guc_submission_is_used(guc))
> +		return -ENODEV;
> +
> +	*val = guc->num_guc_ids;
> +
> +	return 0;
> +}
> +
> +static int guc_num_id_set(void *data, u64 val)
> +{
> +	struct intel_guc *guc = data;
> +
> +	if (!intel_guc_submission_is_used(guc))
> +		return -ENODEV;
> +
> +	if (val > guc->max_guc_ids)
> +		val = guc->max_guc_ids;
> +	else if (val < 256)
> +		val = 256;
> +
> +	guc->num_guc_ids = val;
> +
> +	return 0;
> +}
> +DEFINE_SIMPLE_ATTRIBUTE(guc_num_id_fops, guc_num_id_get, guc_num_id_set, "%lld\n");
> +
>   void intel_guc_debugfs_register(struct intel_guc *guc, struct dentry *root)
>   {
>   	static const struct debugfs_gt_file files[] = {
>   		{ "guc_info", &guc_info_fops, NULL },
>   		{ "guc_registered_contexts", &guc_registered_contexts_fops, NULL },
>   		{ "guc_slpc_info", &guc_slpc_info_fops, &intel_eval_slpc_support},
> +		{ "guc_num_id", &guc_num_id_fops, NULL },
>   	};
>   
>   	if (!intel_guc_is_supported(guc))
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 8235e49bb347..68742b612692 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -2716,7 +2716,8 @@ g2h_context_lookup(struct intel_guc *guc, u32 desc_idx)
>   
>   	if (unlikely(desc_idx >= guc->max_guc_ids)) {
>   		drm_err(&guc_to_gt(guc)->i915->drm,
> -			"Invalid desc_idx %u", desc_idx);
> +			"Invalid desc_idx %u, max %u",
> +			desc_idx, guc->max_guc_ids);
>   		return NULL;
>   	}
>   