linux-kernel - Re: [PATCH] PCI: pciehp: clear cmd_busy bit when Command Completed in polling mode

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Date:   Thu, 18 Nov 2021 19:00:45 +0800
From:   luanshi <zhangliguang@...ux.alibaba.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lukas Wunner <lukas@...ner.de>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Amey Narkhede <ameynarkhede03@...il.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: pciehp: clear cmd_busy bit when Command Completed in
 polling mode

Hi Bjorn & Lukas & Kuppuswamy & Amey,

Gentle ping! Any comments on this patch?


在 2021/11/11 13:42, Liguang Zhang 写道:
> This patch fixes this problem that on driver probe from system startup,
> pciehp checks the Presence Detect State bit in the Slot Status register
> to bring up an occupied slot or bring down an unoccupied slot. If empty
> slot's power status is on, turn power off. The Hot-Plug interrupt isn't
> requested yet, so avoid triggering a notification by calling
> pcie_disable_notification().
>
> Both the CCIE and HPIE bits are masked in pcie_disable_notification(),
> when we issue a hotplug command, pcie_wait_cmd() will polling the
> Command Completed bit instead of waiting for an interrupt. But cmd_busy
> bit was not cleared when Command Completed which results in timeouts
> like this in pciehp_power_off_slot() and pcie_init_notification():
>
>    pcieport 0000:00:03.0: pciehp: Timeout on hotplug command 0x01c0
> (issued 2264 msec ago)
>    pcieport 0000:00:03.0: pciehp: Timeout on hotplug command 0x05c0
> (issued 2288 msec ago)
>
> Signed-off-by: Liguang Zhang <zhangliguang@...ux.alibaba.com>
> ---
>   drivers/pci/hotplug/pciehp_hpc.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 83a0fa119cae..8698aefc6041 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -98,6 +98,8 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>   		if (slot_status & PCI_EXP_SLTSTA_CC) {
>   			pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
>   						   PCI_EXP_SLTSTA_CC);
> +			ctrl->cmd_busy = 0;
> +			smp_mb();
>   			return 1;
>   		}
>   		msleep(10);