linux-kernel - Re: [PATCH 3/8] PCI: qcom: Do not advertise hotplug capability for IPs v2.7.0 and v1.9.0

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Message-ID: <870ea899-b405-8061-93fe-cf50de595808@linaro.org>
Date:   Sat, 6 May 2023 15:01:10 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        lpieralisi@...nel.org, kw@...ux.com, bhelgaas@...gle.com
Cc:     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
Subject: Re: [PATCH 3/8] PCI: qcom: Do not advertise hotplug capability for
 IPs v2.7.0 and v1.9.0

On 06/05/2023 10:31, Manivannan Sadhasivam wrote:
> SoCs making use of Qcom PCIe controller IPs v2.7.0 and v1.9.0 do not
> support 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, let's clear the HPC bit in
> PCI_EXP_SLTCAP register as a part of the post init sequence to not
> advertise the hotplug capability for the controller.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>   drivers/pci/controller/dwc/pcie-qcom.c | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...il.com>

-- 
With best wishes
Dmitry