From: John Stultz <john.stultz@linaro.org>
To: Vardan Mikayelyan <Vardan.Mikayelyan@synopsys.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
Wei Xu <xuwei5@hisilicon.com>, Guodong Xu <guodong.xu@linaro.org>,
Amit Pundir <amit.pundir@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
John Youn <John.Youn@synopsys.com>,
Douglas Anderson <dianders@chromium.org>,
Chen Yu <chenyu56@huawei.com>,
Kishon Vijay Abraham I <kishon@ti.com>,
Felipe Balbi <felipe.balbi@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: [RFC][PATCH 2/5] usb: dwc2: Workaround case where GOTGCTL state is wrong
Date: Tue, 13 Dec 2016 12:40:15 -0800 [thread overview]
Message-ID: <CALAqxLV3uEzjM1Ljwv+=_NRL5XVb5syQ7Ehbq7u5ecPObBsqhQ@mail.gmail.com> (raw)
In-Reply-To: <A62D4564EAF812438095D5571C2BF7D7FCC24529@am04wembxa.internal.synopsys.com>
On Tue, Dec 13, 2016 at 4:28 AM, Vardan Mikayelyan
<Vardan.Mikayelyan@synopsys.com> wrote:
> On 12/13/2016 11:12 AM, John Stultz wrote:
>> When removing a USB-A to USB-otg adapter cable, we get a change
>> status irq, and then in dwc2_conn_id_status_change, we
>> erroniously see the GOTGCTL_CONID_B flag set. This causes us to
>> get stuck in the "while (!dwc2_is_device_mode(hsotg))" loop,
>> spitting out "Waiting for Peripheral Mode, Mode=Host" warnings
>> until it fails out many seconds later.
>>
>> This patch works around the issue by re-reading the GOTGCTL
>> state to check if the GOTGCTL_CONID_B is still set and if not
>> restarting the change status logic.
>>
>> I suspect this isn't the best solution, but it seems to work
>> well for me.
>>
>> Feedback would be greatly appreciated!
>>
>> Cc: Wei Xu <xuwei5@hisilicon.com>
>> Cc: Guodong Xu <guodong.xu@linaro.org>
>> Cc: Amit Pundir <amit.pundir@linaro.org>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: John Youn <johnyoun@synopsys.com>
>> Cc: Douglas Anderson <dianders@chromium.org>
>> Cc: Chen Yu <chenyu56@huawei.com>
>> Cc: Kishon Vijay Abraham I <kishon@ti.com>
>> Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Cc: linux-usb@vger.kernel.org
>> Acked-by: John Youn <johnyoun@synopsys.com>
>> Signed-off-by: John Stultz <john.stultz@linaro.org>
>> ---
>> drivers/usb/dwc2/hcd.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
>> index df5a065..a3f34dd 100644
>> --- a/drivers/usb/dwc2/hcd.c
>> +++ b/drivers/usb/dwc2/hcd.c
>> @@ -3199,7 +3199,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
>> dev_dbg(hsotg->dev, "gotgctl=%0x\n", gotgctl);
>> dev_dbg(hsotg->dev, "gotgctl.b.conidsts=%d\n",
>> !!(gotgctl & GOTGCTL_CONID_B));
>> -
>> +again:
>> /* B-Device connector (Device Mode) */
>> if (gotgctl & GOTGCTL_CONID_B) {
>> /* Wait for switch to device mode */
>> @@ -3210,6 +3210,9 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
>> dwc2_is_host_mode(hsotg) ? "Host" :
>> "Peripheral");
>> usleep_range(20000, 40000);
>> + gotgctl = dwc2_readl(hsotg->regs + GOTGCTL);
>> + if (!(gotgctl & GOTGCTL_CONID_B))
>> + goto again;
>> if (++count > 250)
>> break;
>> }
>>
> Hi John Stultz,
>
> When it goes to ":again", it will go to else anyways. I'll suggest
> alternative way to do this. Please see below.
Sounds good. I've made the change.
> Also you can add "Reviewed-by: Vardan Mikayelyan <mvardan@synopsys.com>"
Thanks so much for your review!
-john
next prev parent reply other threads:[~2016-12-13 21:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-13 7:09 [RFC][PATCH 0/5] Fixes and workarounds for dwc2 on HiKey board John Stultz
2016-12-13 7:09 ` [RFC][PATCH 1/5] usb: dwc2: Avoid sleeping while holding hsotg->lock John Stultz
2016-12-13 7:09 ` [RFC][PATCH 2/5] usb: dwc2: Workaround case where GOTGCTL state is wrong John Stultz
2016-12-13 12:28 ` Vardan Mikayelyan
2016-12-13 20:40 ` John Stultz [this message]
2016-12-13 7:09 ` [RFC][PATCH 3/5] usb: dwc2: Force port resume on switching to device mode John Stultz
2016-12-13 7:09 ` [RFC][PATCH 4/5] usb: dwc2: Avoid suspending if we're in gadget mode John Stultz
2016-12-13 7:09 ` [RFC][PATCH 5/5] usb: dwc2: Add a quirk to allow speed negotiation for Hisilicon Hi6220 John Stultz
2016-12-13 13:24 ` Alan Stern
2016-12-13 19:23 ` John Stultz
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