Subject: [PATCH v2] iio: adc: lpc18xx_adc: Reorder clk_get_rate function call

clk_get_rate is not guaranteed to work if called before clk_prepare_enable.

Reorder clk_get_rate, so it's called after clk_prepare_enable and
after devm_add_action_or_reset of lpc18xx_clk_disable.

Suggested-by: Jonathan Cameron <[email protected]>
Acked-by: Vladimir Zapolskiy <[email protected]>
Signed-off-by: Andr? Gustavo Nakagomi Lopez <[email protected]>
---
Change log V1 -> V2:
-Fixed typo
-Added appropriate Suggested-by and Acked-by tags
drivers/iio/adc/lpc18xx_adc.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
index ceefa4d793cf..ae9c9384f23e 100644
--- a/drivers/iio/adc/lpc18xx_adc.c
+++ b/drivers/iio/adc/lpc18xx_adc.c
@@ -157,9 +157,6 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk),
"error getting clock\n");

- rate = clk_get_rate(adc->clk);
- clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
-
adc->vref = devm_regulator_get(&pdev->dev, "vref");
if (IS_ERR(adc->vref))
return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref),
@@ -192,6 +189,9 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
if (ret)
return ret;

+ rate = clk_get_rate(adc->clk);
+ clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
+
adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
LPC18XX_ADC_CR_PDN;
writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);
--
2.33.0


2021-10-28 13:38:57

by Jonathan Cameron

[permalink] [raw]
Subject: Re: [PATCH v2] iio: adc: lpc18xx_adc: Reorder clk_get_rate function call

On Mon, 25 Oct 2021 09:19:50 -0300
André Gustavo Nakagomi Lopez <[email protected]> wrote:

> clk_get_rate is not guaranteed to work if called before clk_prepare_enable.
>
> Reorder clk_get_rate, so it's called after clk_prepare_enable and
> after devm_add_action_or_reset of lpc18xx_clk_disable.
>
> Suggested-by: Jonathan Cameron <[email protected]>
> Acked-by: Vladimir Zapolskiy <[email protected]>
> Signed-off-by: André Gustavo Nakagomi Lopez <[email protected]>

Thanks. I tweaked the message a little and added a note that this was not
a fix for this particular platform. Good to avoid chance of cut and paste
into another driver!

Jonathan

> ---
> Change log V1 -> V2:
> -Fixed typo
> -Added appropriate Suggested-by and Acked-by tags
> drivers/iio/adc/lpc18xx_adc.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
> index ceefa4d793cf..ae9c9384f23e 100644
> --- a/drivers/iio/adc/lpc18xx_adc.c
> +++ b/drivers/iio/adc/lpc18xx_adc.c
> @@ -157,9 +157,6 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
> return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk),
> "error getting clock\n");
>
> - rate = clk_get_rate(adc->clk);
> - clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
> -
> adc->vref = devm_regulator_get(&pdev->dev, "vref");
> if (IS_ERR(adc->vref))
> return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref),
> @@ -192,6 +189,9 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> + rate = clk_get_rate(adc->clk);
> + clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
> +
> adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
> LPC18XX_ADC_CR_PDN;
> writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);