Re: [v4,06/11] drm/xe/vrsr: Initialize VRSR feature

["Poosa, Karthik" <karthik.poosa@intel.com>]

On 29-05-2025 16:46, Badal Nilawar wrote:
> Add the API xe_pm_vrsr_enable to initialize the VRSR feature,
> requesting AUX power limit and PERST# assertion delay.
>
> V2: Add retry mechanism while requesting AUX power limit
>
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_device_types.h |   1 +
>   drivers/gpu/drm/xe/xe_pcode_api.h    |   7 ++
>   drivers/gpu/drm/xe/xe_pm.c           | 105 ++++++++++++++++++++++++++-
>   drivers/gpu/drm/xe/xe_pm.h           |   1 +
>   4 files changed, 113 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 3a15b3a252fd..5f9a1a358468 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -7,6 +7,7 @@
>   #define _XE_DEVICE_TYPES_H_
>   
>   #include <linux/pci.h>
> +#include <linux/pci-acpi.h>
>   
>   #include <drm/drm_device.h>
>   #include <drm/drm_file.h>
> diff --git a/drivers/gpu/drm/xe/xe_pcode_api.h b/drivers/gpu/drm/xe/xe_pcode_api.h
> index 127d4d26c4cf..f54ef03799d4 100644
> --- a/drivers/gpu/drm/xe/xe_pcode_api.h
> +++ b/drivers/gpu/drm/xe/xe_pcode_api.h
> @@ -43,6 +43,13 @@
>   #define	    POWER_SETUP_I1_SHIFT		6	/* 10.6 fixed point format */
>   #define	    POWER_SETUP_I1_DATA_MASK		REG_GENMASK(15, 0)
>   
> +#define	  PCODE_D3_VRAM_SELF_REFRESH	0x71
> +#define	    PCODE_D3_VRSR_SC_DISABLE	0x0
> +#define	    PCODE_D3_VRSR_SC_ENABLE	0x1
> +#define     PCODE_D3_VRSR_SC_AUX_PL_AND_PERST_DELAY	0x2
> +#define	    POWER_D3_VRSR_PERST_MASK	REG_GENMASK(31, 16)
> +#define	    POWER_D3_VRSR_AUX_PL_MASK	REG_GENMASK(15, 0)
> +
>   #define   PCODE_FREQUENCY_CONFIG		0x6e
>   /* Frequency Config Sub Commands (param1) */
>   #define     PCODE_MBOX_FC_SC_READ_FUSED_P0	0x0
> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> index c9395e62d21d..278f2eeeaab6 100644
> --- a/drivers/gpu/drm/xe/xe_pm.c
> +++ b/drivers/gpu/drm/xe/xe_pm.c
> @@ -5,6 +5,7 @@
>   
>   #include "xe_pm.h"
>   
> +#include <linux/delay.h>
>   #include <linux/fault-inject.h>
>   #include <linux/pm_runtime.h>
>   #include <linux/suspend.h>
> @@ -23,6 +24,7 @@
>   #include "xe_guc.h"
>   #include "xe_irq.h"
>   #include "xe_mmio.h"
> +#include "xe_pcode_api.h"
>   #include "xe_pcode.h"
>   #include "xe_pxp.h"
>   #include "xe_trace.h"
> @@ -260,6 +262,107 @@ static bool xe_pm_vrsr_capable(struct xe_device *xe)
>   	return val & VRAM_SR_SUPPORTED;
>   }
>   
> +static int pci_acpi_aux_power_setup(struct xe_device *xe)
> +{
> +	struct xe_tile *root_tile = xe_device_get_root_tile(xe);
> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> +	struct pci_dev *root_pdev;
> +	int ret;
> +	u32 uval;
> +	u32 aux_pwr_limit;
> +	u32 retry_interval;
> +	u32 perst_delay;
> +
> +	root_pdev = pcie_find_root_port(pdev);
> +	if (!root_pdev)
> +		return -EINVAL;
> +
> +	ret = xe_pcode_read(root_tile, PCODE_MBOX(PCODE_D3_VRAM_SELF_REFRESH,
> +			    PCODE_D3_VRSR_SC_AUX_PL_AND_PERST_DELAY, 0),
> +			    &uval, NULL);
> +
> +	if (ret)
> +		return ret;
> +
> +	aux_pwr_limit = REG_FIELD_GET(POWER_D3_VRSR_AUX_PL_MASK, uval);
> +	perst_delay = REG_FIELD_GET(POWER_D3_VRSR_PERST_MASK, uval);
> +
> +	drm_dbg(&xe->drm, "Aux Power limit = %d mW\n", aux_pwr_limit);
> +	drm_dbg(&xe->drm, "PERST# Assertion delay = %d microseconds\n", perst_delay);
> +
> +retry:
> +	ret = pci_acpi_request_d3cold_aux_power(root_pdev, aux_pwr_limit, &retry_interval);
> +
> +	if (ret == -EAGAIN) {
> +		drm_warn(&xe->drm, "D3cold Aux Power request needs retry interval: %d seconds\n",
> +			 retry_interval);
> +		msleep(retry_interval * 1000);
> +		goto retry;
Instead of indefinite retry, can you retries with count, ~3 times, after 
which we can return failure.
> +	}
> +
> +	if (ret)
> +		return ret;
> +
> +	ret = pci_acpi_add_perst_assertion_delay(root_pdev, perst_delay);
> +
> +	return ret;
> +}
> +
> +static void xe_pm_vrsr_init(struct xe_device *xe)
> +{
> +	int ret;
> +
> +	/* Check if platform support D3Cold VRSR */

This can be rephrased to, "Check if Xe should support VRSR for the platform."

> +	if (!xe->info.has_vrsr)

> +		return;
> +
Can you add a comment here also, viz "Check if GPU firmware supports VRSR"
> +	if (!xe_pm_vrsr_capable(xe))
> +		return;
> +
> +	/*
> +	 * If the VRSR initialization fails, the device will proceed with the regular
> +	 * D3Cold flow
> +	 */
> +	ret = pci_acpi_aux_power_setup(xe);
> +	if (ret) {
> +		drm_info(&xe->drm, "VRSR capable: No\n");
> +		return;
> +	}
> +
> +	xe->d3cold.vrsr_capable = true;
> +	drm_info(&xe->drm, "VRSR capable: Yes\n");
> +}
> +
> +/**
> + * xe_pm_vrsr_enable - Enable VRAM self refresh

as this function does both enable & disable VRSR, this can be renamed to 
xe_pm_set_vrsr(xe, flag)

> + * @xe: The xe device.
> + * @enable: true: Enable, false: Disable
> + *
> + * This function enables the VRSR feature in D3Cold path.
> + *
> + * Return: It returns 0 on success and errno on failure.
> + */
> +int xe_pm_vrsr_enable(struct xe_device *xe, bool enable)
> +{
> +	struct xe_tile *root_tile = xe_device_get_root_tile(xe);
> +	int ret;
> +	u32 uval = 0;
> +
> +	if (!xe->d3cold.vrsr_capable)
> +		return -ENXIO;
> +
> +	drm_dbg(&xe->drm, "%s VRSR\n", enable ? "Enabling" : "Disabling");
> +
> +	if (enable)
> +		ret = xe_pcode_write(root_tile, PCODE_MBOX(PCODE_D3_VRAM_SELF_REFRESH,
> +				     PCODE_D3_VRSR_SC_ENABLE, 0), uval);
> +	else
> +		ret = xe_pcode_write(root_tile, PCODE_MBOX(PCODE_D3_VRAM_SELF_REFRESH,
> +				     PCODE_D3_VRSR_SC_DISABLE, 0), uval);
> +
> +	return ret;
> +}
> +
>   static void xe_pm_runtime_init(struct xe_device *xe)
>   {
>   	struct device *dev = xe->drm.dev;
> @@ -374,7 +477,7 @@ int xe_pm_init(struct xe_device *xe)
>   		err = xe_pm_set_vram_threshold(xe, vram_threshold);
>   		if (err)
>   			goto err_unregister;
> -		xe->d3cold.vrsr_capable = xe_pm_vrsr_capable(xe);
> +		xe_pm_vrsr_init(xe);
>   	}
>   
>   	xe_pm_runtime_init(xe);
> diff --git a/drivers/gpu/drm/xe/xe_pm.h b/drivers/gpu/drm/xe/xe_pm.h
> index 59678b310e55..ba550281b130 100644
> --- a/drivers/gpu/drm/xe/xe_pm.h
> +++ b/drivers/gpu/drm/xe/xe_pm.h
> @@ -35,4 +35,5 @@ bool xe_rpm_reclaim_safe(const struct xe_device *xe);
>   struct task_struct *xe_pm_read_callback_task(struct xe_device *xe);
>   int xe_pm_module_init(void);
>   
> +int xe_pm_vrsr_enable(struct xe_device *xe, bool enable);
>   #endif