From mboxrd@z Thu Jan 1 00:00:00 1970 From: tarun.kanti@ti.com (DebBarma, Tarun Kanti) Date: Thu, 21 Jun 2012 12:04:26 +0530 Subject: [GIT PULL] gpio/omap: cleanups for v3.5 In-Reply-To: <20120621131616.7ac6426f@notabene.brown> References: <874nrmtf47.fsf@ti.com> <20120614101541.39f50aee@notabene.brown> <20120621131616.7ac6426f@notabene.brown> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Jun 21, 2012 at 8:46 AM, NeilBrown wrote: > On Thu, 14 Jun 2012 23:24:10 +0530 "DebBarma, Tarun Kanti" > wrote: > >> On Thu, Jun 14, 2012 at 5:45 AM, NeilBrown wrote: >> > On Fri, 11 May 2012 17:30:48 -0700 Kevin Hilman wrote: >> > >> >> Hi Grant, >> >> >> >> Here's the final round of GPIO cleanups for v3.5. ?This branch is based >> >> on my for_3.5/fixes/gpio branch you just pulled. >> >> >> >> Kevin >> > >> > Hi. >> > >> > ?I'm not sure if it was this series or the following cleanups which broke >> > ?things for me, but I've been trying 3.5-rc2 on my GTA04 and the serial >> > ?console (ttyO2) dies as soon as the omap-gpio driver initialises. >> > >> > ?After some digging I came up with this patch to gpio-omap.c >> > >> > @@ -1124,6 +1124,9 @@ static int __devinit omap_gpio_probe(struct platform_device *pdev) >> > >> > ? ? ? ?platform_set_drvdata(pdev, bank); >> > >> > + ? ? ? if (bank->get_context_loss_count) >> > + ? ? ? ? ? ? ? bank->context_loss_count = >> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? bank->get_context_loss_count(bank->dev); >> > ? ? ? ?pm_runtime_enable(bank->dev); >> > ? ? ? ?pm_runtime_irq_safe(bank->dev); >> > ? ? ? ?pm_runtime_get_sync(bank->dev); >> > >> > which fixes it. >> > >> > What was happening ?was that when omap_gpio_probe calls pm_runtime_get_sync, >> > it calls >> > ?_od_runtime_resume -> pm_generic_runtime_resume -> omap_gpio_runtime_resume >> > ?-> omap_gpio_restore_context >> > >> > and then the serial port stops. >> > I reasoned that the context probably hadn't been set up yet, so restoring >> > from it broke things. >> > Initialising bank->context_loss_count seems sensible and would ensure that >> > we didn't try to restore the context until it has actually been lost. >> >> I thought the following code exactly does that. That is context_lost_cnt_after >> would be zero until there is context loss. The bank->context_loss_count is zero >> at the beginning. So, (context_lost_cnt_after != bank->context_loss_count) would >> be false and hence context restore should NOT happen? Not sure if I am >> over looking >> anything here.... >> >> omap_gpio_runtime_resume(...) >> { >> ... >> ? ? ? ? if (bank->get_context_loss_count) { >> ? ? ? ? ? ? ? ? context_lost_cnt_after = >> ? ? ? ? ? ? ? ? ? ? ? ? bank->get_context_loss_count(bank->dev); >> ? ? ? ? ? ? ? ? if (context_lost_cnt_after != bank->context_loss_count) { >> ? ? ? ? ? ? ? ? ? ? ? ? omap_gpio_restore_context(bank); >> ? ? ? ? ? ? ? ? } else { >> ? ? ? ? ? ? ? ? ? ? ? ? spin_unlock_irqrestore(&bank->lock, flags); >> ? ? ? ? ? ? ? ? ? ? ? ? return 0; >> ? ? ? ? ? ? ? ? } >> ? ? ? ? } >> ... >> } > > Hi, > ?I've looked more closely at this now. > > The problem is that the initial context loss count is *not* zero. ?Not always. > The context loss count is the sum of > > ? ? ? ?count = pwrdm->state_counter[PWRDM_POWER_OFF]; > ? ? ? ?count += pwrdm->ret_logic_off_counter; > > ? ? ? ?for (i = 0; i < pwrdm->banks; i++) > ? ? ? ? ? ? ? ?count += pwrdm->ret_mem_off_counter[i]; > > (from ?pwrdm_get_context_loss_count()). > > These are initlialised in _pwrdm_register > > ? ? ? ?/* Initialize the powerdomain's state counter */ > ? ? ? ?for (i = 0; i < PWRDM_MAX_PWRSTS; i++) > ? ? ? ? ? ? ? ?pwrdm->state_counter[i] = 0; > > ? ? ? ?pwrdm->ret_logic_off_counter = 0; > ? ? ? ?for (i = 0; i < pwrdm->banks; i++) > ? ? ? ? ? ? ? ?pwrdm->ret_mem_off_counter[i] = 0; > > ? ? ? ?pwrdm_wait_transition(pwrdm); > ? ? ? ?pwrdm->state = pwrdm_read_pwrst(pwrdm); > ? ? ? ?pwrdm->state_counter[pwrdm->state] = 1; > > > What I'm seeing is that for wkup_pwrdm and dpll{3,4,5}_pwrdm, > the state that pwrdm_read_pwrst returns is PWRDM_POWER_OFF. > So that state_counter gets initialised to '1', and so the initial > context_loss_count, which includes that counter, is also '1'. > I think it is the wkup_pwrdm that covers the GPIOs that are causing problems > for me. I just put a log in omap_gpio_probe() to see the value of context_loss_count. GPIO Bank 0 (WKUP Domain) always shows the count as '1'. [ 0.169494] omap_gpio omap_gpio.0: context_loss_count=1 [ 0.170227] gpiochip_add: registered GPIOs 0 to 31 on device: gpio [ 0.170471] OMAP GPIO hardware version 0.1 [ 0.170623] omap_gpio omap_gpio.1: context_loss_count=0 [ 0.170928] gpiochip_add: registered GPIOs 32 to 63 on device: gpio [ 0.171295] omap_gpio omap_gpio.2: context_loss_count=0 [ 0.171600] gpiochip_add: registered GPIOs 64 to 95 on device: gpio [ 0.171936] omap_gpio omap_gpio.3: context_loss_count=0 [ 0.172241] gpiochip_add: registered GPIOs 96 to 127 on device: gpio [ 0.172576] omap_gpio omap_gpio.4: context_loss_count=0 [ 0.172882] gpiochip_add: registered GPIOs 128 to 159 on device: gpio [ 0.173217] omap_gpio omap_gpio.5: context_loss_count=0 [ 0.173522] gpiochip_add: registered GPIOs 160 to 191 on device: gpio -- Tarun > > So either there is something seriously wrong with pwrdm_read_pwrst and it > shouldn't be reporting that the wkup_pwrdm is off, or we need to initialise > bank->context_loss_count like my patch does. > > NeilBrown