Re: [PATCH v3 1/2] drm/xe/xe_debugfs: Exposure of G-State and pcie link state residency counters through debugfs

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

Hi Soham

On 6/3/2025 11:42 PM, Soham Purkait wrote:
>      Add two debugfs node named dgfx_pkg_residencies and dgfx_link_state_residencys
> in order to obtain the G-State residency counter values for G2, G6, G8, G10 &
> ModS and the pcie link state residency counter values for L0, L1 & L1.2
> respectively.
> 
> Signed-off-by: Soham Purkait <soham.purkait@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_debugfs.c | 99 +++++++++++++++++++++++++++++++++
>   1 file changed, 99 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
> index d83cd6ed3fa8..c339f05ce42e 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"
> @@ -185,6 +188,86 @@ static ssize_t wedged_mode_set(struct file *f, const char __user *ubuf,
>   	return size;
>   }
>   
> +static int read_residency_counter(struct xe_device *xe, struct xe_mmio *mmio,
> +				  u64 *dst, u32 offset, char *name)
> +{
> +	int ret = xe_pmt_telem_read(to_pci_dev(xe->drm.dev),
> +				xe_mmio_read32(mmio, PUNIT_TELEMETRY_GUID),
> +				dst, offset, sizeof(u64));

What happens if this call fails? dst will be 0?

> +	if (ret != sizeof(u64))
> +		drm_warn(&xe->drm, "%s residency counter failed to read, ret %d\n", name, ret);
> +
> +	return 0;
> +}
> +
> +static ssize_t dgfx_pkg_residencies_show(struct file *f, char __user *ubuf,
> +					 size_t size, loff_t *pos)
> +{
> +	u64 g_states;

%s/g_states/residency

> +	char buf[256];
> +	int len = 0;
> +	struct xe_device *xe;
> +	struct xe_mmio *mmio;
> +
> +	xe = file_inode(f)->i_private;
> +	xe_pm_runtime_get(xe);
> +	mmio = xe_root_tile_mmio(xe);
> +
> +	g_states = 0;
> +	read_residency_counter(xe, mmio, &g_states, BMG_G2_RESIDENCY_OFFSET, "G2");
> +	len = scnprintf(buf, sizeof(buf), "Package G2: %llu\n", g_states);
> +

There is no check for BMG. Is it applicable only for BMG?

> +	g_states = 0;
> +	read_residency_counter(xe, mmio, &g_states, BMG_G6_RESIDENCY_OFFSET, "G6");
> +	len += scnprintf(buf + len, sizeof(buf) - len, "Package G6: %llu\n", g_states);
> +
> +	g_states = 0;
> +	read_residency_counter(xe, mmio, &g_states, BMG_G8_RESIDENCY_OFFSET, "G8");
> +	len += scnprintf(buf + len, sizeof(buf) - len, "Package G8: %llu\n", g_states);
> +
> +	g_states = 0;
> +	read_residency_counter(xe, mmio, &g_states, BMG_G10_RESIDENCY_OFFSET, "G10");
> +	len += scnprintf(buf + len, sizeof(buf) - len, "Package G10: %llu\n", g_states);
> +
> +	g_states = 0;
> +	read_residency_counter(xe, mmio, &g_states, BMG_MODS_RESIDENCY_OFFSET, "ModS");
> +	len += scnprintf(buf + len, sizeof(buf) - len, "Package ModS: %llu\n", g_states);

Repeated code here. Use a helper

> +
> +	xe_pm_runtime_put(xe);
> +	return simple_read_from_buffer(ubuf, size, pos, buf, len);
> +}
> +
> +static ssize_t dgfx_link_state_residencys_show(struct file *f, char __user *ubuf,
> +					       size_t size, loff_t *pos)
> +{
> +	u64 link_res;
> +	char buf[256];
> +	int len = 0;
> +	struct xe_device *xe;
> +	struct xe_mmio *mmio;
> +
> +	xe = file_inode(f)->i_private;
> +	xe_pm_runtime_get(xe);
> +	mmio = xe_root_tile_mmio(xe);
> +
> +	link_res = 0;
> +	read_residency_counter(xe, mmio, &link_res, PCIE_LINK_L0_RESIDENCY_COUNTER, "PCIE LINK L0");
> +	len = scnprintf(buf, sizeof(buf), "PCIE LINK L0 RESIDENCY :  %llu\n", link_res);
> +
> +	link_res = 0;
> +	read_residency_counter(xe, mmio, &link_res, PCIE_LINK_L1_RESIDENCY_COUNTER, "PCIE LINK L1");
> +	len += scnprintf(buf + len, sizeof(buf) - len, "PCIE LINK L1 RESIDENCY : %llu\n", link_res);
> +
> +	link_res = 0;
> +	read_residency_counter(xe, mmio, &link_res,
> +			       PCIE_LINK_L1_2_RESIDENCY_COUNTER, "PCIE LINK L1.2");
> +	len += scnprintf(buf + len, sizeof(buf) - len,
> +			 "PCIE LINK L1.2 RESIDENCY : %llu\n", link_res);

Use a helper

> +
> +	xe_pm_runtime_put(xe);
> +	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,
> @@ -226,6 +309,16 @@ static const struct file_operations atomic_svm_timeslice_ms_fops = {
>   	.write = atomic_svm_timeslice_ms_set,
>   };
>   
> +static const struct file_operations dgfx_pkg_residencies_fops = {
> +	.owner = THIS_MODULE,
> +	.read = dgfx_pkg_residencies_show,
> +};
> +
> +static const struct file_operations dgfx_link_state_residencys_fops = {
> +	.owner = THIS_MODULE,
> +	.read = dgfx_link_state_residencys_show,
> +};
> +
>   void xe_debugfs_register(struct xe_device *xe)
>   {
>   	struct ttm_device *bdev = &xe->ttm;
> @@ -249,6 +342,12 @@ void xe_debugfs_register(struct xe_device *xe)
>   	debugfs_create_file("atomic_svm_timeslice_ms", 0600, root, xe,
>   			    &atomic_svm_timeslice_ms_fops);
>   
> +	debugfs_create_file("dgfx_pkg_residencies", 0444, root, xe,
> +			    &dgfx_pkg_residencies_fops);
> +
> +	debugfs_create_file("dgfx_link_state_residencys", 0444, root, xe,
> +			    &dgfx_link_state_residencys_fops);
If these are for dgfx there needs to be dgfx check

Thanks
Riana


> +
>   	for (mem_type = XE_PL_VRAM0; mem_type <= XE_PL_VRAM1; ++mem_type) {
>   		man = ttm_manager_type(bdev, mem_type);
>