linux-kernel - Re: [PATCH 4/8] PCI: qcom: Do not advertise hotplug capability for IPs v2.3.3 and v2.9.0

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Message-ID: <9a493ef9-c869-6671-38c0-d295ae8ebd63@linaro.org>
Date:   Sat, 6 May 2023 15:07:50 +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 4/8] PCI: qcom: Do not advertise hotplug capability for
 IPs v2.3.3 and v2.9.0

On 06/05/2023 15:01, Dmitry Baryshkov wrote:
> On 06/05/2023 10:31, Manivannan Sadhasivam wrote:
>> SoCs making use of Qcom PCIe controller IPs v2.3.3 and v2.9.0 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 not set 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 | 1 -
>>   1 file changed, 1 deletion(-)
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...il.com>
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry