[PATCH 1/2] drm/xe/vf: Don't check CTC_MODE[0] if VF

[Matt Roper]

On Tue, Mar 11, 2025 at 12:40:41PM +0100, Michal Wajdeczko wrote:
> Starting from commit 18778b5fdd01 ("drm/xe: Eliminate usage of
> TIMESTAMP_OVERRIDE") we access the CTC_MODE register only to warn
> if it has undocumented value.  There is no point in doing that on
> the VF driver.  While here, move this check to a helper function.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

> ---
>  drivers/gpu/drm/xe/xe_gt_clock.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_clock.c b/drivers/gpu/drm/xe/xe_gt_clock.c
> index 2a958c92d8ea..fca38738e610 100644
> --- a/drivers/gpu/drm/xe/xe_gt_clock.c
> +++ b/drivers/gpu/drm/xe/xe_gt_clock.c
> @@ -40,11 +40,8 @@ static u32 get_crystal_clock_freq(u32 rpm_config_reg)
>  	}
>  }
>  
> -int xe_gt_clock_init(struct xe_gt *gt)
> +static void check_ctc_mode(struct xe_gt *gt)
>  {
> -	u32 c0 = xe_mmio_read32(&gt->mmio, RPM_CONFIG0);
> -	u32 freq = 0;
> -
>  	/*
>  	 * CTC_MODE[0] = 1 is definitely not supported for Xe2 and later
>  	 * platforms.  In theory it could be a valid setting for pre-Xe2
> @@ -57,7 +54,17 @@ int xe_gt_clock_init(struct xe_gt *gt)
>  	 */
>  	if (xe_mmio_read32(&gt->mmio, CTC_MODE) & CTC_SOURCE_DIVIDE_LOGIC)
>  		xe_gt_warn(gt, "CTC_MODE[0] is set; this is unexpected and undocumented\n");
> +}
>  
> +int xe_gt_clock_init(struct xe_gt *gt)
> +{
> +	u32 freq;
> +	u32 c0;
> +
> +	if (!IS_SRIOV_VF(gt_to_xe(gt)))
> +		check_ctc_mode(gt);
> +
> +	c0 = xe_mmio_read32(&gt->mmio, RPM_CONFIG0);
>  	freq = get_crystal_clock_freq(c0);
>  
>  	/*
> -- 
> 2.47.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation