Re: [Intel-gfx] [PATCH] drm/i915/gt: Perf_limit_reasons are only available for Gen11+

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Sep 28, 2022 at 12:02:12PM -0700, Ashutosh Dixit wrote:
> Register GT0_PERF_LIMIT_REASONS (0x1381a8) is available only for
> Gen11+. Therefore ensure perf_limit_reasons sysfs files are created only
> for Gen11+. Otherwise on Gen < 5 accessing these files results in the
> following oops:
> 
> <1> [88.829420] BUG: unable to handle page fault for address: ffffc90000bb81a8
> <1> [88.829438] #PF: supervisor read access in kernel mode
> <1> [88.829447] #PF: error_code(0x0000) - not-present page
> 
> This patch is a backport of the drm-tip commit 0d2d201095e9 to
> drm-intel-fixes. The backport is not identical to 0d2d201095e9, it only
> includes the sysfs portions of 0d2d201095e9. The debugfs portion of
> 0d2d201095e9 is not available in drm-intel-fixes so has not been
> backported.

Thanks for the backport. While pushing it, I adjusted the commit message
to make checkpatch happier and to also ensure we included the previous
reviews and patchwork link to the backport.

> 
> Bspec: 20008
> Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/6863
> Fixes: fa68bff7cf27 ("drm/i915/gt: Add sysfs throttle frequency interfaces")
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
> index 73a8b46e0234..d09a0e845d09 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
> @@ -545,8 +545,7 @@ static INTEL_GT_RPS_BOOL_ATTR_RO(throttle_reason_ratl, RATL_MASK);
>  static INTEL_GT_RPS_BOOL_ATTR_RO(throttle_reason_vr_thermalert, VR_THERMALERT_MASK);
>  static INTEL_GT_RPS_BOOL_ATTR_RO(throttle_reason_vr_tdc, VR_TDC_MASK);
>  
> -static const struct attribute *freq_attrs[] = {
> -	&dev_attr_punit_req_freq_mhz.attr,
> +static const struct attribute *throttle_reason_attrs[] = {
>  	&attr_throttle_reason_status.attr,
>  	&attr_throttle_reason_pl1.attr,
>  	&attr_throttle_reason_pl2.attr,
> @@ -763,12 +762,20 @@ void intel_gt_sysfs_pm_init(struct intel_gt *gt, struct kobject *kobj)
>  	if (!is_object_gt(kobj))
>  		return;
>  
> -	ret = sysfs_create_files(kobj, freq_attrs);
> +	ret = sysfs_create_file(kobj, &dev_attr_punit_req_freq_mhz.attr);
>  	if (ret)
>  		drm_warn(&gt->i915->drm,
> -			 "failed to create gt%u throttle sysfs files (%pe)",
> +			 "failed to create gt%u punit_req_freq_mhz sysfs (%pe)",
>  			 gt->info.id, ERR_PTR(ret));
>  
> +	if (GRAPHICS_VER(gt->i915) >= 11) {
> +		ret = sysfs_create_files(kobj, throttle_reason_attrs);
> +		if (ret)
> +			drm_warn(&gt->i915->drm,
> +				 "failed to create gt%u throttle sysfs files (%pe)",
> +				 gt->info.id, ERR_PTR(ret));
> +	}
> +
>  	if (HAS_MEDIA_RATIO_MODE(gt->i915) && intel_uc_uses_guc_slpc(&gt->uc)) {
>  		ret = sysfs_create_files(kobj, media_perf_power_attrs);
>  		if (ret)
> -- 
> 2.34.1
>