From: Pavan Kondeti <quic_pkondeti@quicinc.com>
To: Rohith Kollalsi <quic_rkollals@quicinc.com>
Cc: <mathias.nyman@linux.intel.com>,
<mika.westerberg@linux.intel.com>, <quic_ajaya@quicinc.com>,
<quic_pkondeti@quicinc.com>, <linux-usb@vger.kernel.org>
Subject: Re: [PATCH 5.10 211/290] xhci: Fix repeated xhci wake after suspend due to uncleared internal wake state
Date: Thu, 18 Nov 2021 15:34:34 +0530 [thread overview]
Message-ID: <20211118100434.GA7133@hu-pkondeti-hyd.qualcomm.com> (raw)
In-Reply-To: <977d2868-e1cf-9b33-79b3-18e96b9a30c8@quicinc.com>
+linux-usb
On Thu, Nov 18, 2021 at 03:21:54PM +0530, Rohith Kollalsi wrote:
> Hi Mathias,
>
> This mail is regarding your upstream change in xhci file. There is a
> potential issue with your change which can cause noc error due to unclocked
> access.
>
> Consider a case where a headset is connected to device and nothing is
> playing. As nothing is playing, usb bus wouldn't be active which leads to
> run time suspend ( i think this feature is not present upstream) as a part
> of which xhci_suspend will be called. Now all the clocks are also switched
> off. Now again when pm_suspend occurs due to disconnect, then again
> xhci_suspend occurs, but now registers can be accessed with clocks off
> leading to unclocked access. Can you please consider below change to prevent
> unclocked access.
>
>
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>
> index 2728027..aaf212d 100644
>
> --- a/drivers/usb/host/xhci.c
>
> +++ b/drivers/usb/host/xhci.c
>
> @@ -1013,13 +1013,13 @@ int xhci_suspend(struct xhci_hcd *xhci, bool
> do_wakeup)
>
> xhci->shared_hcd->state != HC_STATE_SUSPENDED)
>
> return -EINVAL;
>
> + if (!HCD_HW_ACCESSIBLE(hcd)) ---> this will prevent unclocked access
> when xhci_suspend occurs during second time during pm_suspend
>
> + return 0;
>
> +
>
> /* Clear root port wake on bits if wakeup not allowed. */
>
> xhci_disable_hub_port_wake(xhci, &xhci->usb3_rhub, do_wakeup);
>
> xhci_disable_hub_port_wake(xhci, &xhci->usb2_rhub, do_wakeup);
>
> - if (!HCD_HW_ACCESSIBLE(hcd))
>
> - return 0;
>
> -
>
> xhci_dbc_suspend(xhci);
>
>
> Thanks,
>
> Rohith
parent reply other threads:[~2021-11-18 10:06 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <977d2868-e1cf-9b33-79b3-18e96b9a30c8@quicinc.com>]
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