Re: [PATCH 2/4] drm/xe/xe_debugfs: Exposure of G8 residency counter

[Riana Tauro <riana.tauro@intel.com>]

Hi Soham

On 5/14/2025 1:37 PM, Soham Purkait wrote:
> Add a debugfs node named g8_residency in order to obtain the G8
> residency counter value.

If this can be read by PMT, why a debugfs again?

> 
> Signed-off-by: Soham Purkait <soham.purkait@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_debugfs.c | 37 +++++++++++++++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_debugfs.h |  2 ++
>   2 files changed, 39 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
> index d0503959a8ed..f9ab6a03af29 100644
> --- a/drivers/gpu/drm/xe/xe_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_debugfs.c
> @@ -11,16 +11,19 @@
>   
>   #include <drm/drm_debugfs.h>
>   
> +#include "regs/xe_pmt.h"
>   #include "xe_bo.h"
>   #include "xe_device.h"
>   #include "xe_force_wake.h"
>   #include "xe_gt_debugfs.h"
>   #include "xe_gt_printk.h"
>   #include "xe_guc_ads.h"
> +#include "xe_mmio.h"
>   #include "xe_pm.h"
>   #include "xe_pxp_debugfs.h"
>   #include "xe_sriov.h"
>   #include "xe_step.h"
> +#include "xe_vsec.h"
>   
>   #ifdef CONFIG_DRM_XE_DEBUG
>   #include "xe_bo_evict.h"
> @@ -185,12 +188,43 @@ static ssize_t wedged_mode_set(struct file *f, const char __user *ubuf,
>   	return size;
>   }
>   > +static ssize_t g8_residency_show(struct file *f, char __user *ubuf,
> +				 size_t size, loff_t *pos)
> +{
> +	u64 reg_val;
> +	char buf[32];
> +	int len = 0;
> +	int ret = 0;
> +	struct xe_device *xe;
> +	struct xe_mmio *mmio;
> +
> +	xe = file_inode(f)->i_private;

runtime_get/put missing

> +	mmio = xe_root_tile_mmio(xe);
> +	ret = xe_pmt_telem_read(to_pci_dev(xe->drm.dev),
> +				xe_mmio_read32(mmio, PUNIT_TELEMETRY_GUID),
> +				&reg_val,
> +				BMG_G8_RESIDENCY_OFFSET,
> +				sizeof(reg_val));

error needs to be handled?

> +
> +	drm_warn(&xe->drm, "G8 Residency read from mbx 0x%016llx, ret %d\n",
> +		 reg_val, ret);

warn gets flagged in CI. Remove this

> +
> +	len = scnprintf(buf, sizeof(buf), "%llu\n", reg_val);
> +
> +	return simple_read_from_buffer(ubuf, size, pos, buf, len);
> +}
> +
>   static const struct file_operations wedged_mode_fops = {
>   	.owner = THIS_MODULE,
>   	.read = wedged_mode_show,
>   	.write = wedged_mode_set,
>   };
>   
> +static const struct file_operations g8_residency_fops = {
> +	.owner = THIS_MODULE,
> +	.read = g8_residency_show,
> +};
> +
>   void xe_debugfs_register(struct xe_device *xe)
>   {
>   	struct ttm_device *bdev = &xe->ttm;
> @@ -211,6 +245,9 @@ void xe_debugfs_register(struct xe_device *xe)
>   	debugfs_create_file("wedged_mode", 0600, root, xe,
>   			    &wedged_mode_fops);
>   
> +	debugfs_create_file("g8_residency", 0444, root, xe,
> +			    &g8_residency_fops);

Since there are multiple residency files they can be under one folder 
maybe (/sys/kernel/debug/gtidle/) similar to the sysfs

> +
>   	for (mem_type = XE_PL_VRAM0; mem_type <= XE_PL_VRAM1; ++mem_type) {
>   		man = ttm_manager_type(bdev, mem_type);
>   
> diff --git a/drivers/gpu/drm/xe/xe_debugfs.h b/drivers/gpu/drm/xe/xe_debugfs.h
> index 17f4c2f1b5e4..86868a3cd379 100644
> --- a/drivers/gpu/drm/xe/xe_debugfs.h
> +++ b/drivers/gpu/drm/xe/xe_debugfs.h
> @@ -8,6 +8,8 @@
>   
>   struct xe_device;
>   
> +#define BMG_G8_RESIDENCY_OFFSET			(0x540)
These should be in same file as register

Thanks
Riana> +
>   #ifdef CONFIG_DEBUG_FS
>   void xe_debugfs_register(struct xe_device *xe);
>   #else