linux-kernel - Re: [PATCH 13/17] pwm: cros-ec: Remove cros_ec_cmd_xfer

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Date:   Mon, 3 Feb 2020 16:33:17 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Prashant Malani <pmalani@...omium.org>,
        linux-kernel@...r.kernel.org
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        "open list:PWM SUBSYSTEM" <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH 13/17] pwm: cros-ec: Remove cros_ec_cmd_xfer_status()


On 30/1/20 21:31, Prashant Malani wrote:
> Convert one existing usage of cros_ec_cmd_xfer_status() to
> cros_ec_send_cmd_msg(), which accomplishes the same thing but also does
> the EC message struct setup,and is defined in platform/chrome and is
> accessible by other modules.
> 
> For the other usage, switch it to using cros_ec_cmd_xfer(), since the
> calling functions rely on the result field of the struct cros_ec_command
> struct that is used.
> 
> Signed-off-by: Prashant Malani <pmalani@...omium.org>
> ---
>  drivers/pwm/pwm-cros-ec.c | 27 +++++++++------------------
>  1 file changed, 9 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-cros-ec.c b/drivers/pwm/pwm-cros-ec.c
> index 89497448d21775..8bf610a6529e7e 100644
> --- a/drivers/pwm/pwm-cros-ec.c
> +++ b/drivers/pwm/pwm-cros-ec.c
> @@ -32,25 +32,14 @@ static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
>  
>  static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
>  {
> -	struct {
> -		struct cros_ec_command msg;
> -		struct ec_params_pwm_set_duty params;
> -	} __packed buf;
> -	struct ec_params_pwm_set_duty *params = &buf.params;
> -	struct cros_ec_command *msg = &buf.msg;
> -
> -	memset(&buf, 0, sizeof(buf));
> +	struct ec_params_pwm_set_duty params = {0};
>  
> -	msg->version = 0;
> -	msg->command = EC_CMD_PWM_SET_DUTY;
> -	msg->insize = 0;
> -	msg->outsize = sizeof(*params);
> -
> -	params->duty = duty;
> -	params->pwm_type = EC_PWM_TYPE_GENERIC;
> -	params->index = index;
> +	params.duty = duty;
> +	params.pwm_type = EC_PWM_TYPE_GENERIC;
> +	params.index = index;
>  
> -	return cros_ec_cmd_xfer_status(ec, msg);
> +	return cros_ec_send_cmd_msg(ec, 0, EC_CMD_PWM_SET_DUTY, &params,
> +				    sizeof(params), NULL, 0);
>  }
>  
>  static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index,
> @@ -78,11 +67,13 @@ static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index,
>  	params->pwm_type = EC_PWM_TYPE_GENERIC;
>  	params->index = index;
>  
> -	ret = cros_ec_cmd_xfer_status(ec, msg);
> +	ret = cros_ec_cmd_xfer(ec, msg);

Why? There is a good reason we introduced the cros_ec_cmd_xfer_status.

IMO the purpose of introduce the new wrapper only makes sense if we can cover
_all_ the cases, so we can remove cros_ec_cmd_xfer_status and make
cros_ec_cmd_xfer private to cros_ec_proto.

Is not possible to use the new wrapper here?

>  	if (result)
>  		*result = msg->result;

Hmm, I see, that's the problem ...

This driver will need a bit of rework but I think could be possible to use the
wrapper.

>  	if (ret < 0)
>  		return ret;
> +	else if (msg->result != EC_RES_SUCCESS)
> +		return -EPROTO;
>  
>  	return resp->duty;
>  }
>