LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jack Pham <jackp@codeaurora.org>
To: Wesley Cheng <wcheng@codeaurora.org>
Cc: balbi@kernel.org, gregkh@linuxfoundation.org,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup
Date: Mon, 2 Aug 2021 14:33:01 -0700	[thread overview]
Message-ID: <20210802213301.GG25299@jackp-linux.qualcomm.com> (raw)
In-Reply-To: <1627691374-15711-1-git-send-email-wcheng@codeaurora.org>

Hi Wesley,

On Fri, Jul 30, 2021 at 05:29:34PM -0700, Wesley Cheng wrote:
> If the device is already in the runtime suspended state, any call to
> the pullup routine will issue a runtime resume on the DWC3 core
> device.  If the USB gadget is disabling the pullup, then avoid having
> to issue a runtime resume, as DWC3 gadget has already been
> halted/stopped.
> 
> This fixes an issue where the following condition occurs:
> 
> usb_gadget_remove_driver()
> -->usb_gadget_disconnect()
>  -->dwc3_gadget_pullup(0)
>   -->pm_runtime_get_sync() -> ret = 0
>   -->pm_runtime_put() [async]
> -->usb_gadget_udc_stop()
>  -->dwc3_gadget_stop()
>   -->dwc->gadget_driver = NULL
> ...
> 
> dwc3_suspend_common()
> -->dwc3_gadget_suspend()
>  -->DWC3 halt/stop routine skipped, driver_data == NULL
> 
> This leads to a situation where the DWC3 gadget is not properly
> stopped, as the runtime resume would have re-enabled EP0 and event
> interrupts, and since we avoided the DWC3 gadget suspend, these
> resources were never disabled.
> 
> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
> ---
>  drivers/usb/dwc3/gadget.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index a29a4ca..5d08454 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  	}
>  
>  	/*
> +	 * Avoid issuing a runtime resume if the device is already in the
> +	 * suspended state during gadget disconnect.  DWC3 gadget was already
> +	 * halted/stopped during runtime suspend.
> +	 */
> +	if (!is_on) {
> +		pm_runtime_barrier(dwc->dev);
> +		if (pm_runtime_suspended(dwc->dev))
> +			return 0;
> +	}
> +
> +	/*
>  	 * Check the return value for successful resume, or error.  For a
>  	 * successful resume, the DWC3 runtime PM resume routine will handle
>  	 * the run stop sequence, so avoid duplicate operations here.

Should this also go to stable with Fixes: 77adb8bdf422 ("usb: dwc3:
gadget: Allow runtime suspend if UDC unbinded") ?

Jack

  reply	other threads:[~2021-08-02 21:33 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-31  0:29 Wesley Cheng
2021-08-02 21:33 ` Jack Pham [this message]
2021-08-03  7:58   ` Felipe Balbi
2021-08-04  6:19     ` Wesley Cheng

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210802213301.GG25299@jackp-linux.qualcomm.com \
    --to=jackp@codeaurora.org \
    --cc=balbi@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=wcheng@codeaurora.org \
    --subject='Re: [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).