Re: [PATCH] pwm: imx-tpm: reset module on probe

[Uwe Kleine-König]

Hello,

On Thu, Feb 01, 2024 at 02:22:42PM +0200, Viorel Suman (OSS) wrote:
> From: Viorel Suman <viorel.suman@xxxxxxx>
> 
> Reset Timer PWM module on probe so that the module
> takes the default state after probe is finished.
> 
> Signed-off-by: Viorel Suman <viorel.suman@xxxxxxx>
> Signed-off-by: Florin Leotescu <florin.leotescu@xxxxxxx>

The order of Signed-off-lines is supposed to be in the order that people
touched the patch during submission. So your S-o-b line should be last
and it should ideally use the email address you use for sending out the
patch.

> ---
>  drivers/pwm/pwm-imx-tpm.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
> index 9fc290e647e1..27e6a5342693 100644
> --- a/drivers/pwm/pwm-imx-tpm.c
> +++ b/drivers/pwm/pwm-imx-tpm.c
> @@ -33,6 +33,7 @@
>  #define PWM_IMX_TPM_CnV(n)	(0x24 + (n) * 0x8)
>  
>  #define PWM_IMX_TPM_PARAM_CHAN			GENMASK(7, 0)
> +#define PWM_IMX_TPM_GLOBAL_RST			BIT(1)
>  
>  #define PWM_IMX_TPM_SC_PS			GENMASK(2, 0)
>  #define PWM_IMX_TPM_SC_CMOD			GENMASK(4, 3)
> @@ -362,6 +363,10 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev)
>  	val = readl(tpm->base + PWM_IMX_TPM_PARAM);
>  	tpm->chip.npwm = FIELD_GET(PWM_IMX_TPM_PARAM_CHAN, val);
>  
> +	/* Resets all internal logic and registers */
> +	writel(PWM_IMX_TPM_GLOBAL_RST, tpm->base + PWM_IMX_TPM_GLOBAL);
> +	writel(0, tpm->base + PWM_IMX_TPM_GLOBAL);
> +

This opposes the use case that the bootloader setup the pwm-backlight to
show a splash screen that is simply taken over by Linux without
flickering, right?

Otherwise the commit log should motivate why "the module takes the
default state" is better than the status quo and what this default state
is.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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