linux-kernel - Re: [PATCH v2] hwmon: (pmbus/ibm-cffps) max_power

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Message-ID: <20211002114027.GA1012283@roeck-us.net>
Date:   Sat, 2 Oct 2021 04:40:27 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Brandon Wyman <bjwyman@...il.com>
Cc:     Joel Stanley <joel@....id.au>, openbmc@...ts.ozlabs.org,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eddie James <eajames@...ux.ibm.com>
Subject: Re: [PATCH v2] hwmon: (pmbus/ibm-cffps) max_power_out swap changes

On Tue, Sep 28, 2021 at 08:50:51PM +0000, Brandon Wyman wrote:
> The bytes for max_power_out from the ibm-cffps devices differ in byte
> order for some power supplies.
> 
> The Witherspoon power supply returns the bytes in MSB/LSB order.
> 
> The Rainier power supply returns the bytes in LSB/MSB order.
> 
> The Witherspoon power supply uses version cffps1. The Rainier power
> supply should use version cffps2. If version is cffps1, swap the bytes
> before output to max_power_out.
> 
> Tested:
>     Witherspoon before: 3148. Witherspoon after: 3148.
>     Rainier before: 53255. Rainier after: 2000.
> 
> Signed-off-by: Brandon Wyman <bjwyman@...il.com>
> Reviewed-by: Eddie James <eajames@...ux.ibm.com>

Applied, though ...

> ---
>  drivers/hwmon/pmbus/ibm-cffps.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
> index df712ce4b164..79bfcd2749a6 100644
> --- a/drivers/hwmon/pmbus/ibm-cffps.c
> +++ b/drivers/hwmon/pmbus/ibm-cffps.c
> @@ -171,8 +171,14 @@ static ssize_t ibm_cffps_debugfs_read(struct file *file, char __user *buf,
>  		cmd = CFFPS_SN_CMD;
>  		break;
>  	case CFFPS_DEBUGFS_MAX_POWER_OUT:
> -		rc = i2c_smbus_read_word_swapped(psu->client,
> -						 CFFPS_MAX_POWER_OUT_CMD);
> +		if (cffps1 == psu->version) {

The yoda programming replaced I did.

> +			rc = i2c_smbus_read_word_swapped(psu->client,
> +					CFFPS_MAX_POWER_OUT_CMD);
> +		} else {
> +			rc = i2c_smbus_read_word_data(psu->client,
> +					CFFPS_MAX_POWER_OUT_CMD);
> +		}
> +
>  		if (rc < 0)
>  			return rc;
>