[Intel-xe] [RFC PATCH 2/3] drm/xe : add rc6_residency in ms

[Rodrigo Vivi]

On Wed, May 03, 2023 at 12:12:51PM +0530, Riana Tauro wrote:
> add rc6_residency in ms instead of rc6 residency counter.
> Handle wrap around for the counter
> The counter can still wrap as it relies on the frequency of
> counter being read
> 
> Signed-off-by: Riana Tauro <riana.tauro at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_idle.c | 46 +++++++++++++++++++++++++++++-------
>  1 file changed, 37 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_idle.c b/drivers/gpu/drm/xe/xe_idle.c
> index 231bdb45a6b7..a7e97ddd7253 100644
> --- a/drivers/gpu/drm/xe/xe_idle.c
> +++ b/drivers/gpu/drm/xe/xe_idle.c
> @@ -11,6 +11,8 @@
>  #include "xe_idle.h"
>  #include "xe_mmio.h"
>  
> +#define XE_RC6_MULTIPLIER      1280
> +
>  /*
>   * Render-C States:
>   * ================
> @@ -27,8 +29,7 @@
>   *
>   * device/gt#/gpu_idle/rc* *read-only* files:
>   * - rc_status: Provide the actual immediate status of Render-C: (rc0 or rc6)
> - * - rc6_residency: Provide the rc6_residency in units of 1.28 uSec
> - *		    Prone to overflows.
> + * - rc6_residency_ms: Provide the rc6_residency in ms

Ack on the change to _ms, but let's do keep this in xe_guc_pc for now.

>   */
>  
>  static struct xe_gt *idle_to_gt(struct xe_idle *idle)
> @@ -51,6 +52,35 @@ static struct kobj_type xe_idle_kobj_type = {
>  	.sysfs_ops = &kobj_sysfs_ops,
>  };
>  
> +static u64 rc6_residency_us(struct xe_idle *idle)
> +{
> +	struct xe_gt *gt = idle_to_gt(idle);
> +	u64 cur_residency, delta, overflow_residency, prev_residency;
> +
> +	overflow_residency = BIT_ULL(32);
> +	cur_residency = xe_mmio_read32(gt, GEN6_GT_GFX_RC6.reg);
> +
> +	/*
> +	 * Counter wrap handling
> +	 * Store previous hw counter values for counter wrap-around handling
> +	 * Relying on sufficient frequency of queries otherwise counters can still wrap.
> +	 */
> +	prev_residency = idle->prev_rc6_residency;
> +	idle->prev_rc6_residency = cur_residency;
> +
> +	/* RC6 delta */
> +	if (cur_residency >= prev_residency)
> +		delta = cur_residency - prev_residency;
> +	else
> +		delta = cur_residency + (overflow_residency - prev_residency);
> +
> +	/* Add delta to RC6 extended raw driver copy. */
> +	cur_residency = idle->cur_rc6_residency + delta;
> +	idle->cur_rc6_residency = cur_residency;
> +
> +	return mul_u64_u32_div(cur_residency, XE_RC6_MULTIPLIER, 1000);
> +}
> +
>  static ssize_t
>  rc_status_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
>  {
> @@ -76,11 +106,10 @@ static const struct kobj_attribute rc_status =
>  __ATTR(rc_status, 0444, rc_status_show, NULL);
>  
>  static ssize_t
> -rc6_residency_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +rc6_residency_ms_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
>  {
>  	struct xe_idle *idle = kobj_to_idle(kobj);
>  	struct xe_gt *gt = idle_to_gt(idle);
> -	u32 reg;
>  	ssize_t ret;
>  
>  	xe_device_mem_access_get(gt_to_xe(gt));
> @@ -88,8 +117,7 @@ rc6_residency_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
>  	if (ret)
>  		goto out;
>  
> -	reg = xe_mmio_read32(gt, GEN6_GT_GFX_RC6.reg);
> -	ret = sysfs_emit(buf, "%u\n", reg);
> +	ret = sysfs_emit(buf, "%llu\n", DIV_ROUND_UP_ULL(rc6_residency_us(&gt->idle), 1000));
>  
>  	XE_WARN_ON(xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL));
>  out:
> @@ -97,12 +125,12 @@ rc6_residency_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
>  	return ret;
>  }
>  
> -static const struct kobj_attribute rc6_residency =
> -__ATTR(rc6_residency, 0444, rc6_residency_show, NULL);
> +static const struct kobj_attribute rc6_residency_ms =
> +__ATTR(rc6_residency_ms, 0444, rc6_residency_ms_show, NULL);
>  
>  static const struct attribute *idle_attrs[] = {
>  	&rc_status.attr,
> -	&rc6_residency.attr,
> +	&rc6_residency_ms.attr,
>  	NULL,
>  };
>  
> -- 
> 2.40.0
>