linux-kernel - Re: [PATCH RFC] gpio: omap: refresh the patch “gpio: omap: be more aggressive with pm

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Date:	Tue, 26 Nov 2013 09:34:15 -0600
From:	Felipe Balbi <balbi@...com>
To:	Chao Xu <Chao.Xu@...e.edu>
CC:	<linux-omap@...r.kernel.org>, <santosh.shilimkar@...com>,
	<khilman@...prootsystems.com>, <linus.walleij@...aro.org>,
	<linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Tony Lindgren <tony@...mide.com>, <balbi@...com>
Subject: Re: [PATCH RFC] gpio: omap: refresh the patch “gpio: omap: be more aggressive with pm_runtime” against v3.12-rc5

Hi Chao,

On Mon, Nov 25, 2013 at 09:30:46PM -0600, Chao Xu wrote:
> Refresh the patch “gpio: omap: be more aggressive with pm_runtime” by
> Felipe Balbi against v3.12-rc5. Add version checking so that the
> aggressive pm_runtime only applies to omap4 devices. Tested with
> pandaboard rev a2 through sysfs.
> Signed-off-by: Chao Xu <chao.xu@...e.edu>

Here, you need to keep authorship and mention that you refreshed the
patch, it should look something like:

From: Felipe Balbi <balbi@...com>

try to keep gpio block suspended as much as possible.

Tested with pandaboard and a sysfs exported gpio.

Signed-off-by: Felipe Balbi <balbi at ti.com>

[ chao.xu@...e.edu : refreshed against v3.12-rc5, and added revision
	check to enable aggressive pm_runtime on OMAP4-only ]

Signed-off-by: Chao Xu <chao.xu@...e.edu>

> ---
> According to Mr. Felipe Balbi, the original patch was not accepted
> because interrupts would be missed when GPIO was used as IRQ source.
> But in my tests with pandaboard, interrupts were not missed. This is
> because _idle_sysc() sets the idlemode of gpio module to
> smart-idle-wakeup, and according to OMAP4430 TRM, under this idlemode,
> the gpio can generate an asynchronous wakeup request to the PRCM. And
> after GPIO is awake, the wake-up request is reflected into the
> interrupt status registers.
> 
> A change I made against the original patch is only using the
> aggressive runtime pm scheme on OMAP4 by adding a flag in pdata,
> because I don’t have HW to test OMAP3 or am33xx devices. According to
> the respective TRMs, their GPIO modules also can generate wake-up
> request if the idlemode is set to smart-idle or smart-idle-wakeup. So
> the patch should work for them, too. But I suspect a potential SW bug
> may cause missed interrupts: the am33xx_gpio_sysc.idlemodes is marked
> as capable of SIDLE_SMART_WKUP in omap_hwmod_33xx.c. But according to
> AM335x TRM, _only_ gpio0 is capable of this mode. This may make GPIO
> stuck in force-idle mode and unable to generate wakeup request. And
> thus interrupt will be missed. Again, I don’t have the HW to verify
> whether this is a bug or not :(

Some of this information would be very nice to have in the commit log.

>  drivers/gpio/gpio-omap.c                |  103 ++++++++++++++++++++++++++-----
>  include/linux/platform_data/gpio-omap.h |    1 +
>  2 files changed, 87 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index 89675f8..90661f2 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -76,6 +76,7 @@ struct gpio_bank {
>   int context_loss_count;
>   int power_mode;
>   bool workaround_enabled;
> + bool is_aggressive_pm;
> 
>   void (*set_dataout)(struct gpio_bank *bank, int gpio, int enable);
>   int (*get_context_loss_count)(struct device *dev);
> @@ -473,8 +474,15 @@ static void _disable_gpio_module(struct gpio_bank
> *bank, unsigned offset)
>  static int gpio_is_input(struct gpio_bank *bank, int mask)
>  {
>   void __iomem *reg = bank->base + bank->regs->direction;
> + u32 val;

you see, your email it converting tabs into spaces and loosing all
formatting from the patch. There are lots of tips on how to configure
different emails clients under Documentation/email-clients.txt. You
might also want to use git send-email, which will make patch submission
a lot easier :-)

-- 
balbi

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