linux-kernel - Re: [PATCH 1/1] iio: light: vcnl4035: fixed chip ID check

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Message-ID: <20230430182258.7dbdd39d@jic23-huawei>
Date:   Sun, 30 Apr 2023 18:22:58 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Frank Li <Frank.Li@....com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Petr Machata <petrm@...dia.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Jean Delvare <jdelvare@...e.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Parthiban Nallathambi <pn@...x.de>,
        linux-iio@...r.kernel.org (open list:IIO SUBSYSTEM AND DRIVERS),
        linux-kernel@...r.kernel.org (open list), imx@...ts.linux.dev
Subject: Re: [PATCH 1/1] iio: light: vcnl4035: fixed chip ID check

On Thu, 27 Apr 2023 17:30:37 -0400
Frank Li <Frank.Li@....com> wrote:

> VCNL4035 register(0xE) ID_L and ID_M define as:
> 
>  ID_L: 0x80
>  ID_H: 7:6 (0:0)
>        5:4 (0:0) slave address = 0x60 (7-bit)
>            (0:1) slave address = 0x51 (7-bit)
>            (1:0) slave address = 0x40 (7-bit)
>            (1:0) slave address = 0x41 (7-bit)
>        3:0 Version code default	(0:0:0:0)
> 
> So just check ID_L.

Hi Frank,

Thanks for the fix. A few minor things inline.

> 
> Fixes: 55707294c4eb ("iio: light: Add support for vishay vcnl4035")
> 

No blank line here as the Fixes tag is part of the main tag block.

> Signed-off-by: Frank Li <Frank.Li@....com>

Just to check, the result of this bug is that the driver probe fails
if the slave address isn't 0x60?

> ---
>  drivers/iio/light/vcnl4035.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/light/vcnl4035.c b/drivers/iio/light/vcnl4035.c
> index 3ed37f6057fb..8b7769930f3b 100644
> --- a/drivers/iio/light/vcnl4035.c
> +++ b/drivers/iio/light/vcnl4035.c
> @@ -413,7 +413,7 @@ static int vcnl4035_init(struct vcnl4035_data *data)
>  		return ret;
>  	}
>  
> -	if (id != VCNL4035_DEV_ID_VAL) {
> +	if ((id & 0xff) != VCNL4035_DEV_ID_VAL) {

Please add a define for that 0xff mask and perhaps also use
FIELD_GET() to extract the field for comparison with VCNL4035_DEV_ID_VAL.
Whilst that isn't being done elsewhere in this driver, the heavy use
of set bits means it isn't appropriate anywhere else that I can quickly
identify. You'll also need to include linux/bitfield.h if making that change.

Thanks,

Jonathan

>  		dev_err(&data->client->dev, "Wrong id, got %x, expected %x\n",
>  			id, VCNL4035_DEV_ID_VAL);
>  		return -ENODEV;