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SubjectRe: [PATCH] hwmon: (aspeed-pwm-tacho) Use 24MHz clock
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On 05/08/2018 02:39 AM, Lei YU wrote:
> The clock source for aspeed pwm is set to 24MHz, so use the hard-coded
> clock frequency instead of the one in device tree.
>
> Otherwise, in case of the clock specified in device tree is not 24MHz,
> the fan speed will be incorrect.
>
> Signed-off-by: Lei YU <mine260309@gmail.com>
> ---
> drivers/hwmon/aspeed-pwm-tacho.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c
> index 693a3d5..e83b8df 100644
> --- a/drivers/hwmon/aspeed-pwm-tacho.c
> +++ b/drivers/hwmon/aspeed-pwm-tacho.c
> @@ -922,7 +922,6 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev)
> void __iomem *regs;
> struct resource *res;
> struct device *hwmon;
> - struct clk *clk;
> int ret;
>
> np = dev->of_node;
> @@ -956,12 +955,10 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev)
> regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE, 0);
> regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE_EXT, 0);
>
> - clk = devm_clk_get(dev, NULL);
> - if (IS_ERR(clk))
> - return -ENODEV;
> - priv->clk_freq = clk_get_rate(clk);
> aspeed_set_clock_enable(priv->regmap, true);
> + // The clock source is set to 24MHz

No mixed C/C++ comments in hwmon drivers.

> aspeed_set_clock_source(priv->regmap, 0);
> + priv->clk_freq = 24000000;
>

Are you saying that clk_get_rate() is wrong ? Anyway, if the DT is bad, it should be fixed.
I am not a friend of hacking drivers to fix up bad DTs, and much less so without explanation.
Plus, how do we know that the next chip supported by the driver doesn't have a 32MHz clock ?
Really, please fix the DT.

Guenter

> aspeed_create_type(priv);
>
>

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