linux-kernel - Re: [PATCH 2/5] PCI: dwc: Add new APIs to remove standard and extended Capability

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Message-ID: <aUpDqu8598J4yNHb@ryzen>
Date: Tue, 23 Dec 2025 08:24:26 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Qiang Yu <qiang.yu@....qualcomm.com>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Jingoo Han <jingoohan1@...il.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	Wenbin Yao <wenbin.yao@....qualcomm.com>
Subject: Re: [PATCH 2/5] PCI: dwc: Add new APIs to remove standard and
 extended Capability

Hello Qiang Yu,

I just saw that this patch was queued up.

dw_pcie_remove_ext_capability() basically seems to be identical to:
dw_pcie_ep_hide_ext_capability(), only that your new function does
not require previous cap as an argument (so it seems better).

It seems a bit silly to have two functions that do the same thing,
perhaps you can send a patch that removes dw_pcie_ep_hide_ext_capability()
and updates the only user of that function to use your new function?

Sorry for not seeing this earlier.


Kind regards,
Niklas

On Sun, Nov 09, 2025 at 10:59:41PM -0800, Qiang Yu wrote:
> On some platforms, certain PCIe Capabilities may be present in hardware
> but are not fully implemented as defined in PCIe spec. These incomplete
> capabilities should be hidden from the PCI framework to prevent unexpected
> behavior.
> 
> Introduce two APIs to remove a specific PCIe Capability and Extended
> Capability by updating the previous capability's next offset field to skip
> over the unwanted capability. These APIs allow RC drivers to easily hide
> unsupported or partially implemented capabilities from software.
> 
> Co-developed-by: Wenbin Yao <wenbin.yao@....qualcomm.com>
> Signed-off-by: Wenbin Yao <wenbin.yao@....qualcomm.com>
> Signed-off-by: Qiang Yu <qiang.yu@....qualcomm.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 53 ++++++++++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-designware.h |  2 ++
>  2 files changed, 55 insertions(+)