linux-kernel - Re: [PATCH] usb: typec: fsa4480: Check if the chip is really there

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Message-ID: <2024021210-bacteria-camping-7e48@gregkh>
Date: Mon, 12 Feb 2024 13:48:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Bjorn Andersson <andersson@...nel.org>,
	Marijn Suijten <marijn.suijten@...ainline.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: typec: fsa4480: Check if the chip is really there

On Mon, Feb 12, 2024 at 01:01:30PM +0100, Konrad Dybcio wrote:
> Currently, the driver will happily register the switch/mux devices, and
> so long as the i2c master doesn't complain, the user would never know
> there's something wrong.
> 
> Add a device id check (based on [1]) and return -ENODEV if the read
> fails or returns nonsense.
> 
> Checking the value on a Qualcomm SM6115P-based Lenovo Tab P11 tablet,
> the ID mentioned in the datasheet does indeed show up:
>  fsa4480 1-0042: Found FSA4480 v1.1 (Vendor ID = 0)
> 
> [1] https://www.onsemi.com/pdf/datasheet/fsa4480-d.pdf
> 
> Fixes: 1dc246320c6b ("usb: typec: mux: Add On Semi fsa4480 driver")
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>  drivers/usb/typec/mux/fsa4480.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.c
> index cb7cdf90cb0a..d622f4f3bd54 100644
> --- a/drivers/usb/typec/mux/fsa4480.c
> +++ b/drivers/usb/typec/mux/fsa4480.c
> @@ -13,6 +13,10 @@
>  #include <linux/usb/typec_dp.h>
>  #include <linux/usb/typec_mux.h>
>  
> +#define FSA4480_DEVICE_ID	0x00
> + #define DEVICE_ID_VENDOR_ID	GENMASK(7, 6)
> + #define DEVICE_ID_VERSION_ID	GENMASK(5, 3)
> + #define DEVICE_ID_REV_ID	GENMASK(2, 0)

Why the indent?

And those are _VERY_ generic #defines, please give a better name for
these so you don't conflict with other stuff in the kernel accidentally.

thanks,

greg k-h