Subject: [PATCH v3] pwm: mediatek: fix up PWM4 and PWM5 malfunction on MT7623

From: [email-masked] (Thierry Reding)
Date: Fri, 2 Mar 2018 11:57:19 +0100

On Thu, Mar 01, 2018 at 04:19:12PM +0800, sean.wang at mediatek.com wrote:
> From: Sean Wang <[email-masked]>
> 
> Since the offset for both registers, PWMDWIDTH and PWMTHRES, used to
> control PWM4 or PWM5 are distinct from the other PWMs, whose wrong
> programming on PWM hardware causes waveform cannot be output as expected.
> Thus, the patch adds the extra condition for fixing up the weird case to
> let PWM4 or PWM5 able to work on MT7623.
> 
> v1 -> v2: use pwm45_fixup naming instead of pwm45_quirk
> v2 -> v3: add more tags for Reviewed-by, Fixes, and Cc stable
> 
> Cc: stable at vger.kernel.org
> Fixes: caf065f8fd58 ("pwm: Add MediaTek PWM support")
> Signed-off-by: Sean Wang <[email-masked]>
> Reviewed-by: Matthias Brugger <[email-masked]>
> Cc: Zhi Mao <[email-masked]>
> Cc: John Crispin <[email-masked]>
> Cc: Matthias Brugger <[email-masked]>
> ---
>  drivers/pwm/pwm-mediatek.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
[...]
> @@ -151,9 +156,18 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  		return -EINVAL;
>  	}
>  
> +	if (pc->soc->pwm45_fixup && pwm->hwpwm > 2) {
> +		/*
> +		 * PWM[4,5] has distinct offset for PWMDWIDTH and PWMTHRES
> +		 * from the other PWMs on MT7623.
> +		 */
> +		reg_width = PWM45DWIDTH_FIXUP;
> +		reg_thres = PWM45THRES_FIXUP;
> +	}

I don't understand this. According to the condition above the above
would also use the PWM[4,5] "fixup" register offsets with PWM[3]. Should
the condition be pwm->hwpwm > 3?

Thierry
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