From: peter.chen@nxp.com (Peter Chen)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 08/22] usb: chipidea: Remove locking in ci_udc_start()
Date: Tue, 9 Aug 2016 00:42:07 +0000 [thread overview]
Message-ID: <VI1PR04MB1455B5AF1542F631C84F54F28B1C0@VI1PR04MB1455.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <147070007426.10825.11324896309403492272@sboyd-linaro>
>Quoting Peter Chen (2016-08-06 00:54:35)
>> On Fri, Aug 05, 2016 at 02:53:56PM -0700, Stephen Boyd wrote:
>> > Quoting Peter Chen (2016-07-08 02:45:28)
>> > > On Thu, Jul 07, 2016 at 03:20:59PM -0700, Stephen Boyd wrote:
>> > > > We don't call hw_device_reset() with the ci->lock held, so it
>> > > > doesn't seem like this lock here is protecting anything. Let's
>> > > > just remove it. This allows us to call sleeping functions like
>> > > > phy_init() from within the CI_HDRC_CONTROLLER_RESET_EVENT hook.
>> > > >
>> > > > Cc: Peter Chen <peter.chen@nxp.com>
>> > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> > > > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
>> > > > ---
>> > > > drivers/usb/chipidea/udc.c | 3 ---
>> > > > 1 file changed, 3 deletions(-)
>> > > >
>> > > > diff --git a/drivers/usb/chipidea/udc.c
>> > > > b/drivers/usb/chipidea/udc.c index 065f5d97aa67..f16be4710cdb
>> > > > 100644
>> > > > --- a/drivers/usb/chipidea/udc.c
>> > > > +++ b/drivers/usb/chipidea/udc.c
>> > > > @@ -1719,7 +1719,6 @@ static int ci_udc_start(struct usb_gadget *gadget,
>> > > > struct usb_gadget_driver *driver) {
>> > > > struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget);
>> > > > - unsigned long flags;
>> > > > int retval = -ENOMEM;
>> > > >
>> > > > if (driver->disconnect == NULL) @@ -1746,7 +1745,6 @@
>> > > > static int ci_udc_start(struct usb_gadget *gadget,
>> > > >
>> > > > pm_runtime_get_sync(&ci->gadget.dev);
>> > > > if (ci->vbus_active) {
>> > > > - spin_lock_irqsave(&ci->lock, flags);
>> > > > hw_device_reset(ci);
>> > > > } else {
>> > > > usb_udc_vbus_handler(&ci->gadget, false); @@
>> > > > -1755,7 +1753,6 @@ static int ci_udc_start(struct usb_gadget *gadget,
>> > > > }
>> > > >
>> > > > retval = hw_device_state(ci, ci->ep0out->qh.dma);
>> > > > - spin_unlock_irqrestore(&ci->lock, flags);
>> > > > if (retval)
>> > > > pm_runtime_put_sync(&ci->gadget.dev);
>> > > >
>> > >
>> > > The main purpose for this is disabling interrupt when reset
>> > > controller, in case the unexpected interrupts occur.
>> > >
>> > > You can move this between hw_device_state.
>> > >
>> >
>> > Ok, but we don't hold the ci->lock in ci_udc_vbus_session(). Is that
>> > a bug as well?
>>
>> I agree with your patch. In fact, during the reset controller, the
>> interrupt has not been enabled, it should no unexpected interrupt.
>>
>
>So then we can leave this patch as is? It still isn't clear to me what sequence of
>events that would cause a problem if we don't hold the
>ci->lock around hw_device_state().
Yes. I am ok with this patch. After thinking more, it is safe to be without lock.
And we have this unlock code in nxp internal tree, and without any problems
during 1-2 years.
Acked-by: Peter Chen <peter.chen@nxp.com>
Peter
next prev parent reply other threads:[~2016-08-09 0:42 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-07 22:20 [PATCH v2 00/22] Support qcom's HSIC USB and rewrite USB2 HS phy support Stephen Boyd
2016-07-07 22:20 ` [PATCH v2 01/22] of: device: Support loading a module with OF based modalias Stephen Boyd
2016-07-07 22:20 ` [PATCH v2 02/22] of: device: Export of_device_{get_modalias, uvent_modalias} to modules Stephen Boyd
2016-07-07 22:20 ` [PATCH v2 03/22] usb: ulpi: Support device discovery via device properties Stephen Boyd
2016-07-08 9:04 ` Peter Chen
2016-08-05 21:27 ` Stephen Boyd
2016-08-23 19:58 ` Stephen Boyd
2016-08-24 7:31 ` Heikki Krogerus
2016-08-26 18:54 ` Stephen Boyd
2016-07-18 2:23 ` Rob Herring
2016-08-05 21:40 ` Stephen Boyd
2016-08-23 20:00 ` Stephen Boyd
2016-08-23 23:06 ` Rob Herring
2016-08-24 1:06 ` Stephen Boyd
2016-07-07 22:20 ` [PATCH v2 04/22] usb: chipidea: Only read/write OTGSC from one place Stephen Boyd
2016-07-08 9:14 ` Peter Chen
2016-08-05 21:41 ` Stephen Boyd
2016-08-06 7:42 ` Peter Chen
2016-07-07 22:20 ` [PATCH v2 05/22] usb: chipidea: Handle extcon events properly Stephen Boyd
2016-07-07 22:20 ` [PATCH v2 06/22] usb: chipidea: Add platform flag for wrapper phy management Stephen Boyd
2016-07-08 9:25 ` Peter Chen
2016-08-05 21:46 ` Stephen Boyd
2016-08-06 7:59 ` Peter Chen
2016-08-08 23:46 ` Stephen Boyd
2016-08-09 0:36 ` Peter Chen
2016-07-07 22:20 ` [PATCH v2 07/22] usb: chipidea: Notify events when switching host mode Stephen Boyd
2016-07-08 9:29 ` Peter Chen
2016-07-07 22:20 ` [PATCH v2 08/22] usb: chipidea: Remove locking in ci_udc_start() Stephen Boyd
2016-07-08 9:45 ` Peter Chen
2016-08-05 21:53 ` Stephen Boyd
2016-08-06 7:54 ` Peter Chen
2016-08-08 23:47 ` Stephen Boyd
2016-08-09 0:42 ` Peter Chen [this message]
2016-07-07 22:21 ` [PATCH v2 09/22] usb: chipidea: Kick OTG state machine for AVVIS with vbus extcon Stephen Boyd
2016-07-11 2:25 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 10/22] usb: chipidea: Add support for ULPI PHY bus Stephen Boyd
2016-07-11 3:10 ` Peter Chen
2016-07-11 22:02 ` Stephen Boyd
2016-07-07 22:21 ` [PATCH v2 11/22] usb: chipidea: msm: Mark device as runtime pm active Stephen Boyd
2016-07-11 3:19 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 12/22] usb: chipidea: msm: Rely on core to override AHBBURST Stephen Boyd
2016-07-11 3:24 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 13/22] usb: chipidea: msm: Use hw_write_id_reg() instead of writel Stephen Boyd
2016-07-07 22:21 ` [PATCH v2 14/22] usb: chipidea: msm: Add proper clk and reset support Stephen Boyd
2016-07-11 4:32 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 15/22] usb: chipidea: msm: Mux over secondary phy at the right time Stephen Boyd
2016-07-11 4:43 ` Peter Chen
2016-07-11 22:03 ` Stephen Boyd
2016-07-12 1:07 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 16/22] usb: chipidea: msm: Restore wrapper settings after reset Stephen Boyd
2016-07-11 5:24 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 17/22] usb: chipidea: msm: Make platform data driver local instead of global Stephen Boyd
2016-07-11 5:26 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 18/22] usb: chipidea: msm: Add reset controller for PHY POR bit Stephen Boyd
2016-07-11 5:32 ` Peter Chen
2016-07-11 22:07 ` Stephen Boyd
2016-07-12 1:09 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 19/22] usb: chipidea: msm: Handle phy power states Stephen Boyd
2016-07-11 5:38 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 20/22] usb: chipidea: msm: Be silent on probe defer errors Stephen Boyd
2016-07-11 5:39 ` Peter Chen
2016-07-07 22:21 ` [PATCH v2 21/22] phy: Add support for Qualcomm's USB HSIC phy Stephen Boyd
2016-07-18 2:27 ` Rob Herring
2016-07-07 22:21 ` [PATCH v2 22/22] phy: Add support for Qualcomm's USB HS phy Stephen Boyd
2016-07-18 2:28 ` Rob Herring
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