[PATCH v2] HID: intel-ish-hid: Replace PCI_DEV_FLAGS_NO_D3 with pci_save_state

[PATCH v2] HID: intel-ish-hid: Replace PCI_DEV_FLAGS_NO_D3 with pci_save_state

[Kai-Heng Feng]

PCI_DEV_FLAGS_NO_D3 should not be used outside of PCI core.

Instead, we can use pci_save_state() to hint PCI core that the device
should stay at D0 during suspend. By doing so, PCI core will let the
upstream bridges also stays at D0 so the entire hierachy is in the
correct power state as PCI spec mandates.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v2:
 - Wording change.

 drivers/hid/intel-ish-hid/ipc/pci-ish.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/intel-ish-hid/ipc/pci-ish.c b/drivers/hid/intel-ish-hid/ipc/pci-ish.c
index f491d8b4e24c..ab588b9c8d09 100644
--- a/drivers/hid/intel-ish-hid/ipc/pci-ish.c
+++ b/drivers/hid/intel-ish-hid/ipc/pci-ish.c
@@ -106,6 +106,11 @@ static inline bool ish_should_enter_d0i3(struct pci_dev *pdev)
 	return !pm_suspend_via_firmware() || pdev->device == CHV_DEVICE_ID;
 }
 
+static inline bool ish_should_leave_d0i3(struct pci_dev *pdev)
+{
+	return !pm_resume_via_firmware() || pdev->device == CHV_DEVICE_ID;
+}
+
 /**
  * ish_probe() - PCI driver probe callback
  * @pdev:	pci device
@@ -215,9 +220,7 @@ static void __maybe_unused ish_resume_handler(struct work_struct *work)
 	struct ishtp_device *dev = pci_get_drvdata(pdev);
 	int ret;
 
-	/* Check the NO_D3 flag to distinguish the resume paths */
-	if (pdev->dev_flags & PCI_DEV_FLAGS_NO_D3) {
-		pdev->dev_flags &= ~PCI_DEV_FLAGS_NO_D3;
+	if (ish_should_leave_d0i3(pdev) && !dev->suspend_flag) {
 		disable_irq_wake(pdev->irq);
 
 		ishtp_send_resume(dev);
@@ -281,8 +284,10 @@ static int __maybe_unused ish_suspend(struct device *device)
 			 */
 			ish_disable_dma(dev);
 		} else {
-			/* Set the NO_D3 flag, the ISH would enter D0i3 */
-			pdev->dev_flags |= PCI_DEV_FLAGS_NO_D3;
+			/* Save state so PCI core will keep the device at D0,
+			 * the ISH would enter D0i3
+			 */
+			pci_save_state(pdev);
 
 			enable_irq_wake(pdev->irq);
 		}
-- 
2.17.1

Re: [PATCH v2] HID: intel-ish-hid: Replace PCI_DEV_FLAGS_NO_D3 with pci_save_state

[Srinivas Pandruvada]

On Fri, 2020-06-19 at 22:02 +0800, Kai-Heng Feng wrote:
> PCI_DEV_FLAGS_NO_D3 should not be used outside of PCI core.
> 
> Instead, we can use pci_save_state() to hint PCI core that the device
> should stay at D0 during suspend. By doing so, PCI core will let the
> upstream bridges also stays at D0 so the entire hierachy is in the
> correct power state as PCI spec mandates.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> v2:
>  - Wording change.
> 
>  drivers/hid/intel-ish-hid/ipc/pci-ish.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hid/intel-ish-hid/ipc/pci-ish.c
> b/drivers/hid/intel-ish-hid/ipc/pci-ish.c
> index f491d8b4e24c..ab588b9c8d09 100644
> --- a/drivers/hid/intel-ish-hid/ipc/pci-ish.c
> +++ b/drivers/hid/intel-ish-hid/ipc/pci-ish.c
> @@ -106,6 +106,11 @@ static inline bool ish_should_enter_d0i3(struct
> pci_dev *pdev)
>  	return !pm_suspend_via_firmware() || pdev->device ==
> CHV_DEVICE_ID;
>  }
>  
> +static inline bool ish_should_leave_d0i3(struct pci_dev *pdev)
> +{
> +	return !pm_resume_via_firmware() || pdev->device ==
> CHV_DEVICE_ID;
> +}
> +
>  /**
>   * ish_probe() - PCI driver probe callback
>   * @pdev:	pci device
> @@ -215,9 +220,7 @@ static void __maybe_unused
> ish_resume_handler(struct work_struct *work)
>  	struct ishtp_device *dev = pci_get_drvdata(pdev);
>  	int ret;
>  
> -	/* Check the NO_D3 flag to distinguish the resume paths */
> -	if (pdev->dev_flags & PCI_DEV_FLAGS_NO_D3) {
> -		pdev->dev_flags &= ~PCI_DEV_FLAGS_NO_D3;
> +	if (ish_should_leave_d0i3(pdev) && !dev->suspend_flag) {
>  		disable_irq_wake(pdev->irq);
>  
>  		ishtp_send_resume(dev);
> @@ -281,8 +284,10 @@ static int __maybe_unused ish_suspend(struct
> device *device)
>  			 */
>  			ish_disable_dma(dev);
>  		} else {
> -			/* Set the NO_D3 flag, the ISH would enter D0i3
> */
> -			pdev->dev_flags |= PCI_DEV_FLAGS_NO_D3;
> +			/* Save state so PCI core will keep the device
> at D0,
> +			 * the ISH would enter D0i3
> +			 */
Better to use multi-line comment style.
Otherwise you can add my ACK.

Thanks,
Srinivas

> +			pci_save_state(pdev);
>  
>  			enable_irq_wake(pdev->irq);
>  		}