linux-kernel - Re: [PATCH v2] usb: typec: fsa4480: Check if the chip is really there

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Message-ID: <wescb5qz3ckdns7bhopehz5vst2mffewyng3wq5zzlu2d37cfd@powc5ybrebpn>
Date: Sat, 27 Jul 2024 14:07:35 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Konrad Dybcio <konradybcio@...nel.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Bjorn Andersson <andersson@...nel.org>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: Re: [PATCH v2] usb: typec: fsa4480: Check if the chip is really there

On Fri, Jul 26, 2024 at 01:43:30PM GMT, Konrad Dybcio wrote:
> From: Konrad Dybcio <konrad.dybcio@...aro.org>
> 
> 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)

So wonderful to have 0 Vendor ID (initially assumed that you are showing
it as an example of an error). But yes, the datasheet has 0 there.

> 
> [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>
> Signed-off-by: Konrad Dybcio <konradybcio@...nel.org>
> ---
> Changes in v2:
> - Prepend the new defines with FSA4480_ to make them more obvious
> - Link to v1: https://lore.kernel.org/r/20240212-topic-fs4480_check-v1-1-d9969e4d6f9a@linaro.org
> ---
>  drivers/usb/typec/mux/fsa4480.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)

With the S-o-B tags fixed:

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry