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Message-ID: <CACRpkdasQEgsOEim5oFMBk-K24SzxYAR17jzuPR3_CTjYZ1hvA@mail.gmail.com>
Date: Wed, 18 Nov 2020 01:38:50 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Srinivas Neeli <srinivas.neeli@...inx.com>
Cc: Bartosz Golaszewski <bgolaszewski@...libre.com>,
Michal Simek <michal.simek@...inx.com>,
Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>,
sgoud@...inx.com, Robert Hancock <hancock@...systems.ca>,
"open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
git@...inx.com
Subject: Re: [LINUX PATCH V3 7/9] gpio: gpio-xilinx: Add support for suspend
and resume
Hi Srinivas,
On Thu, Nov 12, 2020 at 6:13 PM Srinivas Neeli
<srinivas.neeli@...inx.com> wrote:
> Add support for suspend and resume, pm runtime suspend and resume.
> Added free and request calls.
>
> Signed-off-by: Srinivas Neeli <srinivas.neeli@...inx.com>
> ---
> Changes in V3:
> -Created new patch for suspend and resume.
(...)
I'm following the idea here I think.
> @@ -544,6 +618,8 @@ static int xgpio_probe(struct platform_device *pdev)
> + pm_runtime_enable(&pdev->dev);
> + status = pm_runtime_get_sync(&pdev->dev);
> + if (status < 0)
> + goto err_unprepare_clk;
Now the clock is enabled a second time. Because
runtime PM kicks in.
Do this instead:
pm_runtime_get_noresume()
pm_runtime_set_active()
pm_runtime_enable()
Now runtime PM knows it is active and will not call
runtime resume and enable the clock a second time.
> + pm_runtime_put(&pdev->dev);
> return 0;
This is right, now pm runtime will gate the clock
until the first GPIO is requested.
> +err_pm_put:
> + pm_runtime_put_sync(&pdev->dev);
> err_unprepare_clk:
> + pm_runtime_disable(&pdev->dev);
> clk_disable_unprepare(chip->clk);
> return status;
Use this on the errorpath instead:
pm_runtime_put_noidle()
pm_runtime_disable()
clk_disable_unprepare();
Now the code will not call runtime suspend to
gate the clock a second time.
Double-check the references to the clock and check
in debugfs that the clock really gets disabled if you're
not using any GPIOs.
Yours,
Linus Walleij
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