linux-kernel - Re: [PATCH v6 1/2] PCI: Add a helper to check Power Resource Requirements

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Date:   Fri, 18 Oct 2019 10:18:14 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     <bhelgaas@...gle.com>, <linux-pci@...r.kernel.org>,
        <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 1/2] PCI: Add a helper to check Power Resource Requirements _PR3 existence

On Fri, 18 Oct 2019 09:38:47 +0200,
Kai-Heng Feng wrote:
> 
> A driver may want to know the existence of _PR3, to choose different
> runtime suspend behavior. A user will be add in next patch.
> 
> This is mostly the same as nouveau_pr3_present().
> 
> Reported-by: kbuild test robot <lkp@...el.com>

It's confusing -- this particular change isn't reported by the test
bot, but only about the lack of the CONFIG_ACPI ifdef.


thanks,

Takashi

> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v6:
> - Only define the function when CONFIG_ACPI is set.
> v5:
> - Add wording suggestion from Bjorn.
> v4:
> - Let caller to find its upstream port device.
> 
>  drivers/pci/pci.c   | 18 ++++++++++++++++++
>  include/linux/pci.h |  2 ++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e7982af9a5d8..1df99d9e350e 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5856,6 +5856,24 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
>  	return 0;
>  }
>  
> +#ifdef CONFIG_ACPI
> +bool pci_pr3_present(struct pci_dev *pdev)
> +{
> +	struct acpi_device *adev;
> +
> +	if (acpi_disabled)
> +		return false;
> +
> +	adev = ACPI_COMPANION(&pdev->dev);
> +	if (!adev)
> +		return false;
> +
> +	return adev->power.flags.power_resources &&
> +		acpi_has_method(adev->handle, "_PR3");
> +}
> +EXPORT_SYMBOL_GPL(pci_pr3_present);
> +#endif
> +
>  /**
>   * pci_add_dma_alias - Add a DMA devfn alias for a device
>   * @dev: the PCI device for which alias is added
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index f9088c89a534..1d15c5d49cdd 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -2310,9 +2310,11 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
>  
>  void
>  pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
> +bool pci_pr3_present(struct pci_dev *pdev);
>  #else
>  static inline struct irq_domain *
>  pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
> +static bool pci_pr3_present(struct pci_dev *pdev) { return false; }
>  #endif
>  
>  #ifdef CONFIG_EEH
> -- 
> 2.17.1
>