linux-kernel - Re: [PATCH v7 5/5] PCI/AER: Only clear error bits in pcie_clear_device

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Message-ID: <aYGne72Gjb_d9Myd@wunner.de>
Date: Tue, 3 Feb 2026 08:44:59 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Shuai Xue <xueshuai@...ux.alibaba.com>
Cc: Jonathan Cameron <jonathan.cameron@...wei.com>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, bhelgaas@...gle.com,
	kbusch@...nel.org, sathyanarayanan.kuppuswamy@...ux.intel.com,
	mahesh@...ux.ibm.com, oohall@...il.com, terry.bowman@....com,
	tianruidong@...ux.alibaba.com
Subject: Re: [PATCH v7 5/5] PCI/AER: Only clear error bits in
 pcie_clear_device_status()

On Wed, Jan 28, 2026 at 08:45:36PM +0800, Shuai Xue wrote:
> The revised the commit message is:
> 
> PCI/AER: Only clear error bits in PCIe Device Status register
> 
> Currently, pcie_clear_device_status() clears the entire PCIe Device
> Status register (PCI_EXP_DEVSTA), which includes both error status bits
> and other status bits.
> 
> According to PCIe Base Spec r6.0 sec 7.5.3.5, the Device Status register
> contains different types of status bits:

Always cite the latest spec revision, i.e. PCIe r7.0 sec 7.5.3.5.

> - RW1C (read/write 1 to clear) non-error bits: For example, Emergency
>   Power Reduction Detected (bit 6). Unconditionally clearing these bits
>   can interfere with other drivers or subsystems that rely on them.

It would be good to explicitly call out that this bit was introduced with
PCIe r5.0 in 2019 and that it's currently the only writable bit in the
register besides the error bits.

> - Reserved bits: May be used for future features and should be preserved.

Wrong, they're marked "RsvdZ" (not "RsvdP"), so they're supposed to be
written as zero (not preserved).

Thanks,

Lukas