From mboxrd@z Thu Jan 1 00:00:00 1970 From: tarun.kanti@ti.com (DebBarma, Tarun Kanti) Date: Fri, 18 May 2012 10:42:48 +0530 Subject: [PATCH 8/8] gpio/omap: fix missing check in *_runtime_suspend() In-Reply-To: <87y5oqtpnw.fsf@ti.com> References: <1335536018-16004-1-git-send-email-tarun.kanti@ti.com> <1335536018-16004-9-git-send-email-tarun.kanti@ti.com> <87y5oqtpnw.fsf@ti.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, May 18, 2012 at 3:51 AM, Kevin Hilman wrote: > Tarun, Santosh, > > Tarun Kanti DebBarma writes: > >> We do checking for bank->enabled_non_wakeup_gpios in order >> to skip redundant operations. Somehow, the check got missed >> while doing the cleanup series. >> >> Just to make sure that we do context restore correctly in >> *_runtime_resume(), the bank->workaround_enabled check is >> moved after context restore. Otherwise, it would prevent >> context restore when bank->enabled_non_wakeup_gpios is 0. >> >> Cc: Kevin Hilman >> Cc: Tony Lindgren >> Cc: Santosh Shilimkar >> Cc: Cousson, Benoit >> Cc: Grant Likely >> Signed-off-by: Tarun Kanti DebBarma > > I just noticed that this patch has caused some strange problems, notably > with the GPIO IRQ used by smsc911x NIC (Overo, Zoom3, 2430SDP, etc. etc.) > > The patch itself is OK, but it has exposed a bug in other parts of the > context restore path that was previously hidden. > > We seem to have been finding lots of GPIO bugs by just testing the > network chips with GPIO IRQs. ?Can I suggest that a platform with a GPIO > IRQ NIC be added to the test platforms you're using? > >> --- >> ?drivers/gpio/gpio-omap.c | ? 13 ++++++++----- >> ?1 files changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c >> index d238f84..59a4af1 100644 >> --- a/drivers/gpio/gpio-omap.c >> +++ b/drivers/gpio/gpio-omap.c >> @@ -1160,6 +1160,9 @@ static int omap_gpio_runtime_suspend(struct device *dev) >> >> ? ? ? spin_lock_irqsave(&bank->lock, flags); >> >> + ? ? if (!bank->enabled_non_wakeup_gpios) >> + ? ? ? ? ? ? goto update_gpio_context_count; >> + >> ? ? ? /* >> ? ? ? ?* Only edges can generate a wakeup event to the PRCM. >> ? ? ? ?* >> @@ -1235,11 +1238,6 @@ static int omap_gpio_runtime_resume(struct device *dev) >> ? ? ? __raw_writel(bank->context.risingdetect, >> ? ? ? ? ? ? ? ? ? ?bank->base + bank->regs->risingdetect); >> >> - ? ? if (!bank->workaround_enabled) { >> - ? ? ? ? ? ? spin_unlock_irqrestore(&bank->lock, flags); >> - ? ? ? ? ? ? return 0; >> - ? ? } >> - > > My moving this below, you exposed some buggy code that can now get > executed in non-OFF mode, wherease before $SUBJECT patch, it would never > be exectued in non-OFF mode. > >> ? ? ? if (bank->get_context_loss_count) { >> ? ? ? ? ? ? ? context_lost_cnt_after = >> ? ? ? ? ? ? ? ? ? ? ? bank->get_context_loss_count(bank->dev); > > ...right below this line, we have: > > ? ? ? ? ? ? ? ?if (context_lost_cnt_after != bank->context_loss_count || > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?!context_lost_cnt_after) { > ? ? ? ? ? ? ? ? ? ? ? ?omap_gpio_restore_context(bank); > > While we've never hit off-mode, context_lost_cnt_after will always be > zero. ?However, becasue of the !context_lost_cnt_after check there, we > will *always* restore the bank context, even though context has never > been lost. > > I have no idea why that !context_lost_cnt_after check is there, but > clearly it is wrong. ?Now that you moved the 'workraound_enabled' check > below this section, as long as off-mode is disabled, the some GPIO > context will be restored here on *every* runtime PM transition. > > The patch below fixes the problem. > > Grant, after Tarun/Santosh have a chance to review/ack this, can you > still get this in for 3.5? ?If not, getting it into -rc should be fine. > > Kevin > > > From 83874df8e0dd78a3609f5ba81d608df7217fd212 Mon Sep 17 00:00:00 2001 > From: Kevin Hilman > Date: Thu, 17 May 2012 14:52:56 -0700 > Subject: [PATCH] gpio/omap: fix broken context restore for non-OFF mode > ?transitions > > The fix in commit 1b12870 (gpio/omap: fix missing check in > *_runtime_suspend()) exposed another bug in the context restore path. > > Currently, the per-bank context restore happens whenever the context > loss count is different in runtime suspend and runtime resume *and* > whenever the per-bank contex_loss_count == 0: > > ? ? ? ?if (context_lost_cnt_after != bank->context_loss_count || > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?!context_lost_cnt_after) { > ? ? ? ? ? ? ? ?omap_gpio_restore_context(bank); > > Restoring context when the context_lost_cnt_after == 0 is clearly > wrong, since this will be true until the first off-mode transition > (which could be never, if off-mode is never enabled.) ?This check > causes the context to be restored on *every* runtime PM transition. > > Before commit 1b12870 (gpio/omap: fix missing check in > *_runtime_suspend()), this code was never executed in non-OFF mode, so > there were never spurious context restores happening. ?After that > change though, spurious context restores could happen. > > To fix, simply remove the !context_lost_cnt_after check. It is not > needed. > > This bug was found when noticing that the smc911x NIC on 3530/Overo > was not working, and git bisect tracked it down to this patch. ?It > seems that the spurious context restore was causing the smsc911x to > not be properly probed on this platform. > > Cc: Tarun Kanti DebBarma > Cc: Santosh Shilimkar > Signed-off-by: Kevin Hilman Acked-by: Tarun Kanti DebBarma > --- > ?drivers/gpio/gpio-omap.c | ? ?3 +-- > ?1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c > index 9b71f04..b570a6a 100644 > --- a/drivers/gpio/gpio-omap.c > +++ b/drivers/gpio/gpio-omap.c > @@ -1238,8 +1238,7 @@ static int omap_gpio_runtime_resume(struct device *dev) > ? ? ? ?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 || > - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? !context_lost_cnt_after) { > + ? ? ? ? ? ? ? if (context_lost_cnt_after != bank->context_loss_count) { > ? ? ? ? ? ? ? ? ? ? ? ?omap_gpio_restore_context(bank); > ? ? ? ? ? ? ? ?} else { > ? ? ? ? ? ? ? ? ? ? ? ?spin_unlock_irqrestore(&bank->lock, flags); > -- > 1.7.9.2 >