linux-kernel - Re: [PATCH 1/3 v2] usb: dwc2: Improve gadget state disconnection handling

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Date:   Tue, 24 Oct 2017 08:59:06 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     John Stultz <john.stultz@...aro.org>,
        lkml <linux-kernel@...r.kernel.org>
CC:     Wei Xu <xuwei5@...ilicon.com>, Guodong Xu <guodong.xu@...aro.org>,
        "Amit Pundir" <amit.pundir@...aro.org>,
        YongQin Liu <yongqin.liu@...aro.org>,
        John Youn <John.Youn@...opsys.com>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Chen Yu <chenyu56@...wei.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 1/3 v2] usb: dwc2: Improve gadget state disconnection
 handling

On 10/24/2017 1:33 AM, John Stultz wrote:
> In the earlier commit dad3f793f20f ("usb: dwc2: Make sure we
> disconnect the gadget state"), I was trying to fix up the
> fact that we somehow weren't disconnecting the gadget state,
> so that when the OTG port was plugged in the second time we
> would get warnings about the state tracking being wrong.
> 
> (This seems to be due to a quirk of the HiKey board where
> we do not ever get any otg interrupts, particularly the session
> end detected signal. Instead we only see status change
> interrupt.)
> 
> The fix there was somewhat simple, as it just made sure to
> call dwc2_hsotg_disconnect() before we connected things up
> in OTG mode, ensuring the state handling didn't throw errors.
> 
> But in looking at a different issue I was seeing with UDC
> state handling, I realized that it would be much better
> to call dwc2_hsotg_disconnect when we get the state change
> signal moving to host mode.
> 
> Thus, this patch removes the earlier disconnect call I added
> and moves it (and the needed locking) to the host mode
> transition.
> 
> Cc: Wei Xu <xuwei5@...ilicon.com>
> Cc: Guodong Xu <guodong.xu@...aro.org>
> Cc: Amit Pundir <amit.pundir@...aro.org>
> Cc: YongQin Liu <yongqin.liu@...aro.org>
> Cc: John Youn <johnyoun@...opsys.com>
> Cc: Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
> Cc: Douglas Anderson <dianders@...omium.org>
> Cc: Chen Yu <chenyu56@...wei.com>
> Cc: Felipe Balbi <felipe.balbi@...ux.intel.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-usb@...r.kernel.org
> Signed-off-by: John Stultz <john.stultz@...aro.org>
> ---
> v2: Remove the extra dwc2_hsotg_core_init_disconnected() call
>      I had added, as suggested by Minas.
> ---
>   drivers/usb/dwc2/hcd.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index c263114..9bd60ec 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -3277,7 +3277,6 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
>   		dwc2_core_init(hsotg, false);
>   		dwc2_enable_global_interrupts(hsotg);
>   		spin_lock_irqsave(&hsotg->lock, flags);
> -		dwc2_hsotg_disconnect(hsotg);
>   		dwc2_hsotg_core_init_disconnected(hsotg, false);
>   		spin_unlock_irqrestore(&hsotg->lock, flags);
>   		dwc2_hsotg_core_connect(hsotg);
> @@ -3296,8 +3295,12 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
>   		if (count > 250)
>   			dev_err(hsotg->dev,
>   				"Connection id status change timed out\n");
> -		hsotg->op_state = OTG_STATE_A_HOST;
>   
> +		spin_lock_irqsave(&hsotg->lock, flags);
> +		dwc2_hsotg_disconnect(hsotg);
> +		spin_unlock_irqrestore(&hsotg->lock, flags);
> +
> +		hsotg->op_state = OTG_STATE_A_HOST;
>   		/* Initialize the Core for Host mode */
>   		dwc2_core_init(hsotg, false);
>   		dwc2_enable_global_interrupts(hsotg);
> 

This patch is required for the HiKey platform, because the assertion of 
the "Connector ID status change" interrupt is different: asserting on B 
connector unplug and goes to Host mode.
No any side effect on SNPS HAPS-DX platform where ConnIDStsChng 
assertion is correct.

Acked-by: Minas Harutyunyan <hminas@...opsys.com>
Tested-by: Minas Harutyunyan <hminas@...opsys.com>

Thanks,
Minas