Re: [PATCH v7 00/26] gpio/omap: driver cleanup and fixes

DebBarma, Tarun Kanti
2011-09-24T10:41:54Z

Santosh, Kevin,

[...]
>>> After that, pm_runtime_put_sync() is called, which will trigger the
>>> driver's ->runtime_suspend callback.  The ->runtime_suspend() callback
>>> checks bank->mod_usage as well, and if zero, doesn't do anything
>>> (notably, it doesn't disable debounce clocks.)
>> I need some clarification in reproducing/testing the fix on OMAP3430SDP.
>> The first thing I am trying to verify is the code flow of suspend.
>>
>> 1) With no debounce clock enabled, when I enable UART timeouts, I
>> automatically see
>> system going to retention. That is I don't have to type echo mem >
>> /sys/power/state
>> echo 5 > /sys/devices/platform/omap/omap_uart.0/sleep_timeout
>> echo 5 > /sys/devices/platform/omap/omap_uart.1/sleep_timeout
>> echo 5 > /sys/devices/platform/omap/omap_uart.2/sleep_timeout
>>
>> 2) I am do not see the print in omap_gpio_suspend/resume(), but I see
>> the print in
>> *_prepare_for_idle()/*_resume_after_idle().
>>
> Hmmm,
>
> This is mostly happening because you are missing a below
> fix from Kevin in the branch you are testing with.
>
> http://www.mail-archive.com/linux-omap@vger.kernel.org/msg54927.html
> {OMAP: omap_device: fix !CONFIG_SUSPEND case in _noirq handlers}
>
> If you rebase, your branch against 3.1-rc6, you should already
> have this fix. Commit {126caf1376e7}
Yes, this patch was missing in Kevin's branch and was
causing the suspend issue.

As pointed out by Kevin, debounce clock was not getting disabled.
In my testing I was somehow grepping CORE power domain instead
of PER power domain and hence missed it. The fix for the debounce
clock issue is at the end of the email.

- Have re-based the for_3.2/gpio-cleanup branch against 3.1-rc6.
- Dropped [PATCH 26/26] gpio/omap: add dbclk aliases for all gpio modules
as suggested by Kevin since it's already taken care by hwmod.
- Added the debounce clock fix in the end.

With above, PER is hitting low power state in Suspend and Idle path.

Have pushed a branch at below URL with mentioned changes.
git://gitorious.org/omap-sw-develoment/linux-omap-dev.git
for_3.2/kevin/gpio-cleanup

Regards,
Tarun

From 5d9a97197ea5426fc79b7a47dd0fd9c6b6ebbbba Mon Sep 17 00:00:00 2001
From: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Date: Sat, 24 Sep 2011 13:32:32 +0530
Subject: [PATCH] gpio/omap: fix debounce clock handling

GPIO debounce clock can gate the PER power domain transition
and needs to be disabled in GPIO driver suspend.

The debounce clock is not getting disabled in runtime_suspend
callback because of an un-necessary bank->mod_usage check.
In omap_gpio_suspend/resume too, there is no need to do
any operation if the gpio bank is not used.

Remove the un-necessary bank->mod_usage check from
suspend callbacks.

Thanks to Kevin Hilman for pointing out this issue.

Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
---
drivers/gpio/gpio-omap.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index c597303..349e774 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -1107,6 +1107,9 @@ static int omap_gpio_suspend(struct device *dev)
void __iomem *wake_status;
unsigned long flags;

+ if (!bank->mod_usage || !bank->loses_context)
+ return 0;
+
if (!bank->regs->wkup_en || !bank->suspend_wakeup)
return 0;

@@ -1128,6 +1131,9 @@ static int omap_gpio_resume(struct device *dev)
void __iomem *base = bank->base;
unsigned long flags;

+ if (!bank->mod_usage || !bank->loses_context)
+ return 0;
+
if (!bank->regs->wkup_en || !bank->saved_wakeup)
return 0;

@@ -1151,9 +1157,6 @@ static int omap_gpio_runtime_suspend(struct device *dev)
int j;
unsigned long flags;

- if (!bank->mod_usage)
- return 0;
-
spin_lock_irqsave(&bank->lock, flags);
/*
* If going to OFF, remove triggering for all
@@ -1199,9 +1202,6 @@ static int omap_gpio_runtime_resume(struct device *dev)
int j;
unsigned long flags;

- if (!bank->mod_usage)
- return 0;
-
spin_lock_irqsave(&bank->lock, flags);
for (j = 0; j < hweight_long(bank->dbck_enable_mask); j++)
clk_enable(bank->dbck);
--
1.7.0.4
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