Re: [PATCH v3] HID: intel-ish-hid: Replace PCI_DEV_FLAGS_NO_D3 with pci_save_state

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Mon, 2020-06-29 at 12:16 +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 hierarchy is in the
> correct power state as PCI spec mandates.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

> ---
> v3:
>  - Use multi-line comments.
> v2:
>  - Wording change.
> 
>  drivers/hid/intel-ish-hid/ipc/pci-ish.c | 16 +++++++++++-----
>  1 file changed, 11 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..c6d48a8648b7 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 +284,11 @@ 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);
>  		}