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Subject: Re: [PATCH] xhci: State explicitly when the controller is
 inaccessible
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>,
        mathias.nyman@intel.com
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "open list:USB XHCI DRIVER" <linux-usb@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20210518111640.243559-1-kai.heng.feng@canonical.com>
From:   Mathias Nyman <mathias.nyman@linux.intel.com>
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Message-ID: <f5d2e440-e777-7ef1-db4b-0f50a8a5f6e1@linux.intel.com>
Date:   Tue, 18 May 2021 15:21:39 +0300
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Precedence: bulk

On 18.5.2021 14.16, Kai-Heng Feng wrote:
> Sometimes the dmesg says "Controller not ready at resume" because CNR is
> flagged. But what actually happens is that the whole USBSTS becomes
> inaccessible, and the reason could be disabled PCI I/O space or faulty
> firmware/hardware.
> 
> So state the reason explicitly to make the message more clear.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/usb/host/xhci.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index ca9385d22f68..0e6fbe1f4fcc 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -1117,8 +1117,9 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
>  		retval = xhci_handshake(&xhci->op_regs->status,
>  					STS_CNR, 0, 10 * 1000 * 1000);
>  		if (retval) {
> -			xhci_warn(xhci, "Controller not ready at resume %d\n",
> -				  retval);
> +			xhci_warn(xhci, "Controller is %s at resume %d\n",
> +				  retval == -ENODEV ? "inaccessible" :
> +				  "not ready", retval);

Old way did print out retval, and was greppable.
Not sure this is an improvement

-Mathias