linux-kernel - Re: [PATCH v2 0/8] PCI: qcom: Do not advertise hotplug capability

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Message-ID: <20230529085810.GD5633@thinkpad>
Date:   Mon, 29 May 2023 14:28:10 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        kw@...ux.com, bhelgaas@...gle.com, robh@...nel.org,
        andersson@...nel.org, konrad.dybcio@...aro.org,
        linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, steev@...i.org,
        quic_srichara@...cinc.com, dmitry.baryshkov@...aro.org
Subject: Re: [PATCH v2 0/8] PCI: qcom: Do not advertise hotplug capability

On Mon, May 22, 2023 at 11:01:17AM +0200, Lorenzo Pieralisi wrote:
> On Fri, May 19, 2023 at 08:01:09PM +0530, Manivannan Sadhasivam wrote:
> > Hi,
> > 
> > The SoCs making use of Qualcomm PCIe controllers do not support the PCIe hotplug
> > functionality. But the hotplug capability bit is set by default in the hardware.
> > This causes the kernel PCI core to register hotplug service for the controller
> > and send hotplug commands to it. But those commands will timeout generating
> > messages as below during boot and suspend/resume.
> >     
> > [    5.782159] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x03c0 (issued 2020 msec ago)
> > [    5.810161] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x03c0 (issued 2048 msec ago)
> > [    7.838162] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x07c0 (issued 2020 msec ago)
> > [    7.870159] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x07c0 (issued 2052 msec ago)
> >     
> > This not only spams the console output but also induces a delay of a couple of
> > seconds. To fix this issue, this series clears the HPC bit in PCI_EXP_SLTCAP
> > register as a part of the post init sequence for all IP versions to not
> > advertise the hotplug capability for the controller.
> > 
> > Testing
> > =======
> > 
> > This series has been tested on DB845c (SDM845 SoC) and Lenovo Thinkpad X13s
> > (SC8280XP SoC).
> > 
> > Thanks,
> > Mani
> > 
> > Changes in v2:
> > 
> > * Collected tags
> > * Moved the HPC clearing to a separate function and reused across different
> >   configs
> > 
> > Manivannan Sadhasivam (8):
> >   PCI: qcom: Use DWC helpers for modifying the read-only DBI registers
> >   PCI: qcom: Disable write access to read only registers for IP v2.9.0
> >   PCI: qcom: Do not advertise hotplug capability for IPs v2.7.0 and
> >     v1.9.0
> >   PCI: qcom: Do not advertise hotplug capability for IPs v2.3.3 and
> >     v2.9.0
> >   PCI: qcom: Do not advertise hotplug capability for IP v2.3.2
> >   PCI: qcom: Use post init sequence of IP v2.3.2 for v2.4.0
> >   PCI: qcom: Do not advertise hotplug capability for IP v1.0.0
> >   PCI: qcom: Do not advertise hotplug capability for IP v2.1.0
> > 
> >  drivers/pci/controller/dwc/pcie-qcom.c | 73 ++++++++++++++------------
> >  1 file changed, 38 insertions(+), 35 deletions(-)
> > 
> 
> Some patches are signed-off twice, FYI, I can fix that while
> applying.
> 

Sorry for that! I used b4 to apply these patches and that added additional
signed-off-by tag for all patches. Since Dmitry also requested to remove his
gmail tag, I can spin another version once we sort out the comment on patch
2/8.

- Mani

> Lorenzo
> 
> > -- 
> > 2.25.1
> > 

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