Re: [PATCH v2] PCI/PM: Only read PCI_PM_CTRL register when available

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Tue, 22 Aug 2023, Feiyang Chen wrote:

> When the current state is already PCI_D0, pci_power_up() will return
> 0 even though dev->pm_cap is not set. In that case, we should not
> read the PCI_PM_CTRL register in pci_set_full_power_state().

IMHO, this is a bit misleading because after this patch, pci_power_up() 
returns always an error if dev->pm_cap is not set.

-- 
 i.


> Fixes: e200904b275c ("PCI/PM: Split pci_power_up()")
> Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
> ---
>  drivers/pci/pci.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 60230da957e0..7e90ab7b47a1 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1242,9 +1242,6 @@ int pci_power_up(struct pci_dev *dev)
>  		else
>  			dev->current_state = state;
>  
> -		if (state == PCI_D0)
> -			return 0;
> -
>  		return -EIO;
>  	}
>  
> @@ -1302,8 +1299,12 @@ static int pci_set_full_power_state(struct pci_dev *dev)
>  	int ret;
>  
>  	ret = pci_power_up(dev);
> -	if (ret < 0)
> +	if (ret < 0) {
> +		if (dev->current_state == PCI_D0)
> +			return 0;
> +
>  		return ret;
> +	}
>  
>  	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
>  	dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;
>