Re: [PATCH 1/1] drm/i915/guc: Fix release build bug in 'remove log size module parameters'

["Ceraolo Spurio, Daniele" <daniele.ceraolospurio@intel.com>]

On 9/12/2022 6:09 PM, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
>
> A patch was merged to remove the GuC log size override module
> parameters. That patch was broken and caused kernel error messages on
> boot in non CONFIG_DEBUG_GUC|GEM builds:
> [   12.085121] i915 0000:00:02.0: [drm] *ERROR* Zero GuC log crash dump size!
> [   12.092035] i915 0000:00:02.0: [drm] *ERROR* Zero GuC log debug size!
>
> So fit it.
>
> Fixes: f54e515c9180 ("drm/i915/guc: Remove log size module parameters")
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Julia Lawall <Julia.Lawall@inria.fr>
> Cc: Chris Wilson <chris.p.wilson@intel.com>
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc_log.c | 25 +---------------------
>   1 file changed, 1 insertion(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
> index b071973ac41c1..55d3ef93e86f8 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c
> @@ -36,24 +36,6 @@ struct guc_log_section {
>   	const char *name;
>   };
>   
> -static s32 scale_log_param(struct intel_guc_log *log, const struct guc_log_section *section,
> -			   s32 param)
> -{
> -	/* -1 means default */
> -	if (param < 0)
> -		return section->default_val;
> -
> -	/* Check for 32-bit overflow */
> -	if (param >= SZ_4K) {
> -		drm_err(&guc_to_gt(log_to_guc(log))->i915->drm, "Size too large for GuC %s log: %dMB!",
> -			section->name, param);
> -		return section->default_val;
> -	}
> -
> -	/* Param units are 1MB */
> -	return param * SZ_1M;
> -}
> -
>   static void _guc_log_init_sizes(struct intel_guc_log *log)
>   {
>   	struct intel_guc *guc = log_to_guc(log);
> @@ -78,15 +60,10 @@ static void _guc_log_init_sizes(struct intel_guc_log *log)
>   			"capture",
>   		}
>   	};
> -	s32 params[GUC_LOG_SECTIONS_LIMIT] = {
> -		GUC_LOG_DEFAULT_CRASH_BUFFER_SIZE / SZ_1M,
> -		GUC_LOG_DEFAULT_DEBUG_BUFFER_SIZE / SZ_1M,
> -		GUC_LOG_DEFAULT_CAPTURE_BUFFER_SIZE / SZ_1M,
> -	};
>   	int i;
>   
>   	for (i = 0; i < GUC_LOG_SECTIONS_LIMIT; i++)
> -		log->sizes[i].bytes = scale_log_param(log, sections + i, params[i]);
> +		log->sizes[i].bytes = sections[i].default_val;
>   
>   	/* If debug size > 1MB then bump default crash size to keep the same units */
>   	if (log->sizes[GUC_LOG_SECTIONS_DEBUG].bytes >= SZ_1M &&

If the user can't tweak the values anymore then we can guarantee that 
the sizes use the same units and change this if to a BUILD_BUG_ON() to 
check that.
Not a blocker for the fix.

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

Daniele