From patchwork Thu Oct 25 07:00:23 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Santosh Shilimkar X-Patchwork-Id: 1642171 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id E51F0DF264 for ; Thu, 25 Oct 2012 07:02:37 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TRHQr-00026L-8D; Thu, 25 Oct 2012 07:00:45 +0000 Received: from bear.ext.ti.com ([192.94.94.41]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TRHQm-00024e-I6 for linux-arm-kernel@lists.infradead.org; Thu, 25 Oct 2012 07:00:41 +0000 Received: from dbdp20.itg.ti.com ([172.24.170.38]) by bear.ext.ti.com (8.13.7/8.13.7) with ESMTP id q9P70XWn008516; Thu, 25 Oct 2012 02:00:34 -0500 Received: from DBDE71.ent.ti.com (localhost [127.0.0.1]) by dbdp20.itg.ti.com (8.13.8/8.13.8) with ESMTP id q9P70TK1024791; Thu, 25 Oct 2012 12:30:30 +0530 (IST) Received: from dbdp32.itg.ti.com (172.24.170.251) by DBDE71.ent.ti.com (172.24.170.149) with Microsoft SMTP Server id 14.1.323.3; Thu, 25 Oct 2012 12:30:29 +0530 Received: from [172.24.136.169] (smtpvbd.itg.ti.com [172.24.170.250]) by dbdp32.itg.ti.com (8.13.8/8.13.8) with ESMTP id q9P70NYb028909; Thu, 25 Oct 2012 12:30:23 +0530 Message-ID: <5088E387.2050704@ti.com> Date: Thu, 25 Oct 2012 12:30:23 +0530 From: Santosh Shilimkar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 MIME-Version: 1.0 To: Jon Hunter , Kevin Hilman Subject: Re: [PATCH v2] gpio/omap: fix off-mode bug: clear debounce clock enable mask on free/reset References: <1351098641-23917-1-git-send-email-khilman@deeprootsystems.com> <50887197.8010104@ti.com> In-Reply-To: <50887197.8010104@ti.com> X-Spam-Note: CRM114 invocation failed X-Spam-Score: -7.6 (-------) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-7.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [192.94.94.41 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Paul Walmsley , Linus Walleij , Felipe Balbi , Igor Grinberg , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Grazvydas Ignotas X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org On Thursday 25 October 2012 04:24 AM, Jon Hunter wrote: > > On 10/24/2012 12:10 PM, Kevin Hilman wrote: >> From: Kevin Hilman >> >> When a GPIO bank is freed or shutdown, ensure that the banks >> dbck_enable_mask is cleared also. Otherwise, context restore on >> subsequent off-mode transition will restore previous value from the >> shadow copies (bank->context.debounce*) leading to mismatch state >> between driver state and hardware state. >> >> This was discovered when board code was doing >> >> gpio_request_one() >> gpio_set_debounce() >> gpio_free() >> >> which was leaving the GPIO debounce settings in a confused state. If >> that GPIO bank is subsequently used with off-mode enabled, bogus state >> would be restored, leaving GPIO debounce enabled which then prevented >> the CORE powerdomain from transitioning. >> >> To fix, ensure that bank->dbck_enable_mask is cleared when the bank >> is freed/shutdown so debounce state doesn't persist. >> The freed part is fine but I don't understand why it needs to be done on _a_ gpio irq shutdown callback where IRQs related configuration on that one GPIO needs to be cleared. De-bounce clock is surely not IRQ related configuration. >> Special thanks to Grazvydas Ignotas for pointing out a bug in an >> earlier version that would've disabled debounce on any runtime PM >> transition. >> >> Reported-by: Paul Walmsley >> Cc: Igor Grinberg >> Cc: Grazvydas Ignotas >> Signed-off-by: Kevin Hilman >> --- >> v2: only clear mask in free/shutdown, not in runtime PM paths, >> clarified changelog >> Applies on v3.7-rc2. >> >> drivers/gpio/gpio-omap.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c >> index 94cbc84..113b167 100644 >> --- a/drivers/gpio/gpio-omap.c >> +++ b/drivers/gpio/gpio-omap.c >> @@ -539,6 +539,7 @@ static void _reset_gpio(struct gpio_bank *bank, int gpio) >> _set_gpio_irqenable(bank, gpio, 0); >> _clear_gpio_irqstatus(bank, gpio); >> _set_gpio_triggering(bank, GPIO_INDEX(bank, gpio), IRQ_TYPE_NONE); >> + bank->dbck_enable_mask = 0; >> } > > Does this need to be ... > > + bank->dbck_enable_mask &= ~(GPIO_BIT(bank, gpio)); > + _gpio_dbck_disable(bank); > Yes, its a per bank clock. There is an alternate. See below. > There could be more than one gpio using debounce and so we should only > clear the appropriate bit. Also after clearing a bit we could see if we > can disable the debounce clock too. > When I mentioned the clearing in gpio_free() path will do trick, I had something like below in mind. /* This patch should be enough according to me unless and until I am missing mask clear need in irq_shutdown path. It will also take care of disabling of debounce clock as part of runtime suspend callback. Regards, Santosh diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c index dee2856..8574105 100644 --- a/drivers/gpio/gpio-omap.c +++ b/drivers/gpio/gpio-omap.c @@ -629,8 +629,10 @@ static void omap_gpio_free(struct gpio_chip *chip, unsigned offset) * If this is the last gpio to be freed in the bank, * disable the bank module. */ - if (!bank->mod_usage) + if (!bank->mod_usage) { + bank->dbck_enable_mask = 0; pm_runtime_put(bank->dev); + } }