linux-kernel - Re: [PATCH] PCI: Cancel compilation restrictions on function pcie_clear_device

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Message-ID: <20240612201432.GA1035119@bhelgaas>
Date: Wed, 12 Jun 2024 15:14:32 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Songyang Li <leesongyang@...look.com>
Cc: bhelgaas@...gle.com, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH]  PCI: Cancel compilation restrictions on function
 pcie_clear_device_status

On Wed, Jun 12, 2024 at 11:15:43PM +0800, Songyang Li wrote:
> On Tue, 11 Jun 2024 17:34:18 -0500, Bjorn Helgaas wrote:
> > Unindent this.
> 
> > Add "()" after function names.
> 
> > Please explain what this patch does and why we want it.  I can see
> > from the patch that it makes it so pcie_clear_device_status() is
> > always compiled, but the commit log should say that and should say why
> > we need that.
> 
> Thank you for reminding to add "()" after function pcie_clear_device_status.
> The following is a revised patch,and it explains why we need that.
> Thanks,
> 
> Songyang Li
> 
> From 3c1340522565a44ef25d2045e5bee2c0bdb72b32 Mon Sep 17 00:00:00 2001
> From: Songyang Li <leesongyang@...look.com>
> Date: Wed, 12 Jun 2024 22:29:51 +0800
> Subject: [PATCH] PCI: Cancel compilation restrictions on function
>  pcie_clear_device_status()
> 
> Some PCIe devices do not have AER capabilities, but they have
> device status registers. The PCIe device status register and
> AER register are independent PCIe capabilities, so it is
> unreasonable to use CONFIG_PCIEAER for compilation control of
> pcie_clear_device_status(), although which is currently only
> used in the "aer.c", "edr.c", and "err.c". Some operating system
> configurations do not enable the AER feature, but still expect to
> use the device status register for simple RAS. In this case,
> pcie_clear_device_status() can be used to clear the device status
> regs, so this patch can meet the requirements of this scenario.

I think all current any callers of pcie_clear_device_status() are also
under CONFIG_PCIEAER, so I don't think this fixes a current problem.

As you point out, it might make sense to use
pcie_clear_device_status() even without AER, but I think we should
include this change at the time when we add such a use.

If I'm missing a use with the current kernel, let me know.

> Signed-off-by: Songyang Li <leesongyang@...look.com>
> ---
>  drivers/pci/pci.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>  mode change 100644 => 100755 drivers/pci/pci.c
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> old mode 100644
> new mode 100755
> index 35fb1f17a589..e6de55be4c45
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2263,7 +2263,12 @@ int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state)
>  }
>  EXPORT_SYMBOL_GPL(pci_set_pcie_reset_state);
>  
> -#ifdef CONFIG_PCIEAER
> +/**
> + * pcie_clear_device_status - Clear device status.
> + * @dev: the PCI device.
> + *
> + * Clear the device status for the PCI device.
> + */
>  void pcie_clear_device_status(struct pci_dev *dev)
>  {
>  	u16 sta;
> @@ -2271,7 +2276,6 @@ void pcie_clear_device_status(struct pci_dev *dev)
>  	pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &sta);
>  	pcie_capability_write_word(dev, PCI_EXP_DEVSTA, sta);
>  }
> -#endif
>  
>  /**
>   * pcie_clear_root_pme_status - Clear root port PME interrupt status.
> -- 
> 2.34.1
>