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

[Gupta, Anshuman]

> -----Original Message-----
> From: Tauro, Riana <riana.tauro at intel.com>
> Sent: Wednesday, May 3, 2023 12:13 PM
> To: intel-xe at lists.freedesktop.org
> Cc: Tauro, Riana <riana.tauro at intel.com>; Gupta, Anshuman
> <anshuman.gupta at intel.com>; Vivi, Rodrigo <rodrigo.vivi at intel.com>; Dixit,
> Ashutosh <ashutosh.dixit at intel.com>; Nilawar, Badal
> <badal.nilawar at intel.com>
> Subject: [RFC PATCH 2/3] drm/xe : add rc6_residency in ms
> 
> 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
>   */
> 
>  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);
We shall use function pointer here to get the residency, so underlying function can read from
appropriate counter and  abstract it from sysfs show function, same comment for converting to 
ms as well.
Br,
Anshuman Gupta.
> +
> +	/*
> +	 * 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