Re: [Intel-gfx] [PATCH 14/19] drm/i915/perf: Add Wa_1608133521:dg2

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

On Tue, 23 Aug 2022, Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com> wrote:
> DG2 introduces 64 bit counters and OA reports that have 64 bit values
> for fields in the report header - report_id, timestamp, context_id and
> gpu ticks. i915 uses report_id, timestamp and context_id to check for
> valid reports.
>
> In some DG2 variants, only the lower dwords for timestamp, report_id and
> context_id are accessible. Add workaround for such reports.
>
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_perf.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index a28f07923d8f..a858ce57e465 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -310,7 +310,7 @@ static u32 i915_oa_max_sample_rate = 100000;
>   * be used as a mask to align the OA tail pointer. In some of the
>   * formats, R is used to denote reserved field.
>   */
> -static const struct i915_oa_format oa_formats[I915_OA_FORMAT_MAX] = {
> +static struct i915_oa_format oa_formats[I915_OA_FORMAT_MAX] = {

Can't do this. This is shared between devices, and once you make it
mutable and change it, you'll change it for *all* devices.

Your options are having const data for all variants you need, or you
make a device specific copy and modify. The former is generally better
if you usually don't need to modify it.

BR,
Jani.


>  	[I915_OA_FORMAT_A13]	    = { 0, 64 },
>  	[I915_OA_FORMAT_A29]	    = { 1, 128 },
>  	[I915_OA_FORMAT_A13_B8_C8]  = { 2, 128 },
> @@ -4746,6 +4746,13 @@ static void oa_init_supported_formats(struct i915_perf *perf)
>  		/* Wa_16010703925:dg2 */
>  		clear_bit(I915_OAR_FORMAT_A36u64_B8_C8, perf->format_mask);
>   	}
> +
> +	if (IS_DG2_GRAPHICS_STEP(i915, G10, STEP_A0, STEP_B0) ||
> +	    IS_DG2_GRAPHICS_STEP(i915, G11, STEP_A0, STEP_FOREVER)) {
> +		/* Wa_1608133521:dg2 */
> +		oa_formats[I915_OAR_FORMAT_A36u64_B8_C8].header = HDR_32_BIT;
> +		oa_formats[I915_OA_FORMAT_A38u64_R2u64_B8_C8].header = HDR_32_BIT;
> +	}
>  }
>  
>  static void i915_perf_init_info(struct drm_i915_private *i915)

-- 
Jani Nikula, Intel Open Source Graphics Center