Re: [PATCH v3 1/2] drm/xe/xe_survivability: Redesign survivability mode

[Nathan Chancellor <nathan@kernel.org>]

Hi Riana,

On Mon, Dec 08, 2025 at 02:15:41PM +0530, Riana Tauro wrote:
...
>  static void populate_survivability_info(struct xe_device *xe)
>  {
>  	struct xe_survivability *survivability = &xe->survivability;
> -	struct xe_survivability_info *info = survivability->info;
> +	u32 *info = survivability->info;
>  	struct xe_mmio *mmio;
>  	u32 id = 0, reg_value;
> -	char name[NAME_MAX];
>  	int index;
>  
>  	mmio = xe_root_tile_mmio(xe);
> -	set_survivability_info(mmio, info, id, "Capability Info");
> -	reg_value = info[id].value;
> +	set_survivability_info(mmio, info, CAPABILITY_INFO);
> +	reg_value = info[CAPABILITY_INFO];
>  
>  	if (reg_value & HISTORY_TRACKING) {
> -		id++;
> -		set_survivability_info(mmio, info, id, "Postcode Info");
> +		set_survivability_info(mmio, info, POSTCODE_TRACE);
>  
> -		if (reg_value & OVERFLOW_SUPPORT) {
> -			id = REG_FIELD_GET(OVERFLOW_REG_OFFSET, reg_value);
> -			set_survivability_info(mmio, info, id, "Overflow Info");
> -		}
> +		if (reg_value & OVERFLOW_SUPPORT)
> +			set_survivability_info(mmio, info, POSTCODE_TRACE_OVERFLOW);
>  	}
>  
>  	if (reg_value & AUXINFO_SUPPORT) {
>  		id = REG_FIELD_GET(AUXINFO_REG_OFFSET, reg_value);
>  
> -		for (index = 0; id && reg_value; index++, reg_value = info[id].value,
> -		     id = aux_history_offset(reg_value)) {
> -			snprintf(name, NAME_MAX, "Auxiliary Info %d", index);
> -			set_survivability_info(mmio, info, id, name);
> +		for (index = 0; id >= AUX_INFO0 && id < MAX_SCRATCH_REG; index++) {
> +			set_survivability_info(mmio, info, id);
> +			id = aux_history_offset(info[id]);
>  		}
>  	}

After this change as commit f4e9fc967afd ("drm/xe/xe_survivability:
Redesign survivability mode") in -next, Clang (and GCC 16, currently in
development) warns that index is set but unused now because it is only
incremented.

  drivers/gpu/drm/xe/xe_survivability_mode.c:147:6: error: variable 'index' set but not used [-Werror,-Wunused-but-set-variable]
    147 |         int index;
        |             ^

  drivers/gpu/drm/xe/xe_survivability_mode.c: In function 'populate_survivability_info':
  drivers/gpu/drm/xe/xe_survivability_mode.c:147:13: error: variable 'index' set but not used [-Werror=unused-but-set-variable=]
    147 |         int index;
        |             ^~~~~

Should this loop be rewritten to drop index or does index need to be
used somewhow?

Cheers,
Nathan