linux-kernel - Re: [PATCH V3 05/10] PCI/TPH: Introduce API to check interrupt vector mode support

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Message-ID: <20240723222821.GA779373@bhelgaas>
Date: Tue, 23 Jul 2024 17:28:21 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Wei Huang <wei.huang2@....com>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, netdev@...r.kernel.org,
	Jonathan.Cameron@...wei.com, corbet@....net, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	alex.williamson@...hat.com, gospo@...adcom.com,
	michael.chan@...adcom.com, ajit.khaparde@...adcom.com,
	somnath.kotur@...adcom.com, andrew.gospodarek@...adcom.com,
	manoj.panicker2@....com, Eric.VanTassell@....com,
	vadim.fedorenko@...ux.dev, horms@...nel.org, bagasdotme@...il.com,
	bhelgaas@...gle.com
Subject: Re: [PATCH V3 05/10] PCI/TPH: Introduce API to check interrupt
 vector mode support

On Wed, Jul 17, 2024 at 03:55:06PM -0500, Wei Huang wrote:
> Add an API function to allow endpoint device drivers to check
> if the interrupt vector mode is allowed. If allowed, drivers
> can proceed with updating ST tags.

Wrap commit log to fill 75 columns

Wrap code/comments to fit in 80.

Here and below, capitalize technical terms defined in spec ("Interrupt
Vector Mode", "Steering Tag").

> Co-developed-by: Eric Van Tassell <Eric.VanTassell@....com>
> Signed-off-by: Eric Van Tassell <Eric.VanTassell@....com>
> Signed-off-by: Wei Huang <wei.huang2@....com>
> Reviewed-by: Ajit Khaparde <ajit.khaparde@...adcom.com>
> Reviewed-by: Somnath Kotur <somnath.kotur@...adcom.com>
> Reviewed-by: Andy Gospodarek <andrew.gospodarek@...adcom.com>
> ---
>  drivers/pci/pcie/tph.c  | 29 +++++++++++++++++++++++++++++
>  include/linux/pci-tph.h |  3 +++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
> index fb8e2f920712..7183370b0977 100644
> --- a/drivers/pci/pcie/tph.c
> +++ b/drivers/pci/pcie/tph.c
> @@ -39,6 +39,17 @@ static void set_ctrl_reg_req_en(struct pci_dev *pdev, u8 req_type)
>  	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg_val);
>  }
>  
> +static bool int_vec_mode_supported(struct pci_dev *pdev)
> +{
> +	u32 reg_val;
> +	u8 mode;
> +
> +	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg_val);
> +	mode = FIELD_GET(PCI_TPH_CAP_INT_VEC, reg_val);
> +
> +	return !!mode;
> +}
> +
>  void pcie_tph_set_nostmode(struct pci_dev *pdev)
>  {
>  	if (!pdev->tph_cap)
> @@ -60,3 +71,21 @@ void pcie_tph_init(struct pci_dev *pdev)
>  {
>  	pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
>  }
> +
> +/**
> + * pcie_tph_intr_vec_supported() - Check if interrupt vector mode supported for dev
> + * @pdev: pci device
> + *
> + * Return:
> + *        true : intr vector mode supported
> + *        false: intr vector mode not supported
> + */
> +bool pcie_tph_intr_vec_supported(struct pci_dev *pdev)
> +{
> +	if (!pdev->tph_cap || pci_tph_disabled() || !pdev->msix_enabled ||
> +	    !int_vec_mode_supported(pdev))
> +		return false;

IMO the int_vec_mode_supported() helper is overkill and could be
inlined here.  The other booleans can be checked first.

> +
> +	return true;
> +}
> +EXPORT_SYMBOL(pcie_tph_intr_vec_supported);
> diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
> index 8fce3969277c..854677651d81 100644
> --- a/include/linux/pci-tph.h
> +++ b/include/linux/pci-tph.h
> @@ -12,9 +12,12 @@
>  #ifdef CONFIG_PCIE_TPH
>  void pcie_tph_disable(struct pci_dev *dev);
>  void pcie_tph_set_nostmode(struct pci_dev *dev);
> +bool pcie_tph_intr_vec_supported(struct pci_dev *dev);
>  #else
>  static inline void pcie_tph_disable(struct pci_dev *dev) {}
>  static inline void pcie_tph_set_nostmode(struct pci_dev *dev) {}
> +static inline bool pcie_tph_intr_vec_supported(struct pci_dev *dev)
> +{ return false; }
>  #endif
>  
>  #endif /* LINUX_PCI_TPH_H */
> -- 
> 2.45.1
>