Re: [PATCH v2 03/10] pwm: imx: Rewrite imx_pwm_*_v1 code to facilitate switch to atomic pwm operation

Lothar Waßmann
2016-11-02T07:35:07Z

Hi,

On Mon, 31 Oct 2016 06:59:04 +0100 Sascha Hauer wrote:
> As said, even the commit 7b27c160c68 introducing the register clk did not
> enable the clock consistently for all register accesses. Maybe it's best
> to include the following patch so that we can find a clear culprit and
> do not bury the ipg clock changes in larger patches.
>
> Sascha
>
> -----------------------------8<-----------------------------------
>
> From 30b77e83269a58c2cb5ce6de8be647e027030d34 Mon Sep 17 00:00:00 2001
> From: Sascha Hauer <s.hauer@pengutronix.de>
> Date: Mon, 31 Oct 2016 06:45:33 +0100
> Subject: [PATCH] pwm: imx: remove ipg clock
>
> The use of the ipg clock was introduced with commit 7b27c160c6. In the
> commit message it was claimed that the ipg clock is enabled for register
> accesses. This is true for the ->config() callback, but not for the
> ->set_enable() callback. Given that the ipg clock is not consistently
> enabled for all register accesses we can assume that either it is not
> required at all or that the current code does not work.
> Remove the ipg clock code for now so that it's no longer in the way of
> refactoring the driver.
>
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Philipp Zabel <p.zabel@pengutronix.de>
> ---
> drivers/pwm/pwm-imx.c | 19 +------------------
> 1 file changed, 1 insertion(+), 18 deletions(-)
>
> diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> index d600fd5..70609ef2 100644
> --- a/drivers/pwm/pwm-imx.c
> +++ b/drivers/pwm/pwm-imx.c
> @@ -49,7 +49,6 @@
>
> struct imx_chip {
> struct clk *clk_per;
> - struct clk *clk_ipg;
>
> void __iomem *mmio_base;
>
> @@ -204,17 +203,8 @@ static int imx_pwm_config(struct pwm_chip *chip,
> struct pwm_device *pwm, int duty_ns, int period_ns)
> {
> struct imx_chip *imx = to_imx_chip(chip);
> - int ret;
> -
> - ret = clk_prepare_enable(imx->clk_ipg);
> - if (ret)
> - return ret;
>
> - ret = imx->config(chip, pwm, duty_ns, period_ns);
> -
> - clk_disable_unprepare(imx->clk_ipg);
> -
> - return ret;
> + return imx->config(chip, pwm, duty_ns, period_ns);
> }
>
> static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> @@ -293,13 +283,6 @@ static int imx_pwm_probe(struct platform_device *pdev)
> return PTR_ERR(imx->clk_per);
> }
>
> - imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
> - if (IS_ERR(imx->clk_ipg)) {
> - dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
> - PTR_ERR(imx->clk_ipg));
> - return PTR_ERR(imx->clk_ipg);
> - }
> -
> imx->chip.ops = &imx_pwm_ops;
> imx->chip.dev = &pdev->dev;
> imx->chip.base = -1;
>
If the IPG clock is not needed by the driver it should be removed from
DT as well.

Lothar Waßmann