Re: [PATCH v1] drm/xe/pm: Enable WAKE# support

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Oct 24, 2025 at 03:51:48PM +0530, Raag Jadav wrote:
> CRI supports signalling the host through WAKE# pin on smbus alerts while
> in D3cold. Enable/disable this feature based on device/host configuration.
> 
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_device_types.h |  4 ++
>  drivers/gpu/drm/xe/xe_pci.c          |  4 ++
>  drivers/gpu/drm/xe/xe_pcode_api.h    |  5 ++
>  drivers/gpu/drm/xe/xe_pm.c           | 72 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_pm.h           |  1 +
>  5 files changed, 86 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 8f62ee7a73ac..dae2bd06bcea 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -517,6 +517,10 @@ struct xe_device {
>  		 * Default threshold value is 300mb.
>  		 */
>  		u32 vram_threshold;
> +
> +		/** @d3cold.wake: Indicates WAKE# capability of device */
> +		u32 wake;
> +
>  		/** @d3cold.lock: protect vram_threshold */
>  		struct mutex lock;
>  	} d3cold;
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 6e59642e7820..edf63f55f345 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -1105,6 +1105,8 @@ static int xe_pci_suspend(struct device *dev)
>  	if (err)
>  		return err;
>  
> +	xe_pm_set_wake(xe, true);

why does it need to be here and not something static inside xe_pm itself?

> +
>  	/*
>  	 * Enabling D3Cold is needed for S2Idle/S0ix.
>  	 * It is save to allow here since xe_pm_suspend has evicted
> @@ -1156,6 +1158,8 @@ static int xe_pci_runtime_suspend(struct device *dev)
>  	if (err)
>  		return err;
>  
> +	xe_pm_set_wake(xe, xe->d3cold.allowed);
> +
>  	pci_save_state(pdev);
>  
>  	if (xe->d3cold.allowed) {
> diff --git a/drivers/gpu/drm/xe/xe_pcode_api.h b/drivers/gpu/drm/xe/xe_pcode_api.h
> index 92bfcba51e19..3f8d43c1b4fe 100644
> --- a/drivers/gpu/drm/xe/xe_pcode_api.h
> +++ b/drivers/gpu/drm/xe/xe_pcode_api.h
> @@ -50,6 +50,11 @@
>  #define	READ_PL_FROM_FW				0x1
>  #define	READ_PL_FROM_PCODE			0x0
>  
> +#define   PCODE_D3COLD_WAKE			0x5A
> +#define     READ_MODE				0x0
> +#define     WRITE_MODE				0x1
> +#define       I2C_WAKE_ENABLE			REG_BIT(1)

please share the spec with me

> +
>  #define   PCODE_LATE_BINDING			0x5C
>  #define     GET_CAPABILITY_STATUS		0x0
>  #define       V1_FAN_SUPPORTED			REG_BIT(0)
> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> index 53507e09f7bc..30e4a787b9cb 100644
> --- a/drivers/gpu/drm/xe/xe_pm.c
> +++ b/drivers/gpu/drm/xe/xe_pm.c
> @@ -7,6 +7,8 @@
>  
>  #include <linux/fault-inject.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/pm_wakeup.h>
> +#include <linux/string_choices.h>
>  #include <linux/suspend.h>
>  
>  #include <drm/drm_managed.h>
> @@ -22,6 +24,7 @@
>  #include "xe_i2c.h"
>  #include "xe_irq.h"
>  #include "xe_late_bind_fw.h"
> +#include "xe_pcode_api.h"
>  #include "xe_pcode.h"
>  #include "xe_pxp.h"
>  #include "xe_sriov_vf_ccs.h"
> @@ -422,6 +425,74 @@ static int xe_pm_notifier_callback(struct notifier_block *nb,
>  	return NOTIFY_DONE;
>  }
>  
> +void xe_pm_set_wake(struct xe_device *xe, bool d3cold)
> +{
> +	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;
> +	bool wakeup;
> +	u32 val = 0;
> +	int ret;
> +
> +	/* WAKE# is not needed, let PME do the job. */
> +	if (!d3cold)
> +		return;

Please NO! check this outside and only call the function if needed instead
of passing the need as argument.

> +
> +	/* Currently WAKE# is supported for I2C only */
> +	if (!REG_FIELD_GET(I2C_WAKE_ENABLE, xe->d3cold.wake))
> +		return;

let's perhaps make it a

static void i2c_set_wake(struct xe_device *xe)
{
...
}

> +
> +	ret = xe_pcode_read(root_tile, PCODE_MBOX(PCODE_D3COLD_WAKE, READ_MODE, 0), &val, NULL);
> +	if (ret)
> +		return;
> +
> +	root_pdev = pcie_find_root_port(pdev);
> +	wakeup = root_pdev && device_may_wakeup(&root_pdev->dev);
> +
> +	if (wakeup)
> +		val |= I2C_WAKE_ENABLE;
> +	else
> +		val &= ~I2C_WAKE_ENABLE;
> +
> +	ret = xe_pcode_write(root_tile, PCODE_MBOX(PCODE_D3COLD_WAKE, WRITE_MODE, 0), val);
> +	if (ret)
> +		return;
> +
> +	drm_dbg(&xe->drm, "WAKE# %s\n", str_enabled_disabled(wakeup));
> +}
> +
> +static void xe_pm_wake_init(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 err;
> +
> +	if (xe->info.platform != XE_CRESCENTISLAND)
> +		return;
> +
> +	err = xe_pcode_read(root_tile, PCODE_MBOX(PCODE_D3COLD_WAKE, READ_MODE, 0),
> +			    &xe->d3cold.wake, NULL);
> +	if (err || !xe->d3cold.wake) {
> +		drm_dbg(&xe->drm, "WAKE# not supported by device\n");
> +		return;
> +	}
> +
> +	root_pdev = pcie_find_root_port(pdev);
> +	if (!root_pdev || !device_can_wakeup(&root_pdev->dev)) {
> +		drm_dbg(&xe->drm, "WAKE# not supported by host\n");
> +		xe->d3cold.wake = 0;
> +		goto out;
> +	}
> +
> +	if (!xe_i2c_present(xe))
> +		xe->d3cold.wake &= ~I2C_WAKE_ENABLE;
> +
> +	drm_dbg(&xe->drm, "WAKE# configuration 0x%08x\n", xe->d3cold.wake);
> +out:
> +	xe_pcode_write(root_tile, PCODE_MBOX(PCODE_D3COLD_WAKE, WRITE_MODE, 0), xe->d3cold.wake);
> +}
> +
>  /**
>   * xe_pm_init - Initialize Xe Power Management
>   * @xe: xe device instance
> @@ -459,6 +530,7 @@ int xe_pm_init(struct xe_device *xe)
>  			goto err_unregister;
>  	}
>  
> +	xe_pm_wake_init(xe);
>  	xe_pm_runtime_init(xe);
>  	return 0;
>  
> diff --git a/drivers/gpu/drm/xe/xe_pm.h b/drivers/gpu/drm/xe/xe_pm.h
> index f7f89a18b6fc..9cedba8a7f80 100644
> --- a/drivers/gpu/drm/xe/xe_pm.h
> +++ b/drivers/gpu/drm/xe/xe_pm.h
> @@ -30,6 +30,7 @@ void xe_pm_runtime_get_noresume(struct xe_device *xe);
>  bool xe_pm_runtime_resume_and_get(struct xe_device *xe);
>  void xe_pm_assert_unbounded_bridge(struct xe_device *xe);
>  int xe_pm_set_vram_threshold(struct xe_device *xe, u32 threshold);
> +void xe_pm_set_wake(struct xe_device *xe, bool d3cold);
>  void xe_pm_d3cold_allowed_toggle(struct xe_device *xe);
>  bool xe_rpm_reclaim_safe(const struct xe_device *xe);
>  struct task_struct *xe_pm_read_callback_task(struct xe_device *xe);
> -- 
> 2.34.1
>