Re: [PATCH 1/4] pwm: Read initial hardware state at request time

[Enric Balletbo i Serra <enric.balletbo@collabora.com>]

Hi,

On 21/10/19 12:57, Thierry Reding wrote:
> The PWM core doesn't need to know about the hardware state of a PWM
> unless there is a user for it. Defer initial hardware readout until
> a PWM is requested.
> 
> As a side-effect, this allows the ->get_state() callback to rely on
> per-PWM data.
> 
> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

Tested on top of 5.4.0-rc4 with 2/4 applied this patch fixes the NULL pointer
dereference as expected. So,

Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

Thanks,
 Enric

> ---
>  drivers/pwm/core.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index f877e77d9184..e067873c6cc5 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -114,6 +114,9 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
>  		}
>  	}
>  
> +	if (pwm->chip->ops->get_state)
> +		pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
> +
>  	set_bit(PWMF_REQUESTED, &pwm->flags);
>  	pwm->label = label;
>  
> @@ -283,9 +286,6 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
>  		pwm->hwpwm = i;
>  		pwm->state.polarity = polarity;
>  
> -		if (chip->ops->get_state)
> -			chip->ops->get_state(chip, pwm, &pwm->state);
> -
>  		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
>  	}
>  
>