Re: [PATCH v4 7/7] usb: typec: mux: Add On Semi fsa4480 driver

Andy Shevchenko
2022-03-07T10:57:30Z

On Sun, Mar 06, 2022 at 07:40:40PM -0800, Bjorn Andersson wrote:
> The ON Semiconductor FSA4480 is a USB Type-C port multimedia switch with
> support for analog audio headsets. It allows sharing a common USB Type-C
> port to pass USB2.0 signal, analog audio, sideband use wires and analog
> microphone signal.
>
> Due to lacking upstream audio support for testing, the audio muxing is
> left untouched, but implementation of muxing the SBU lines is provided
> as a pair of Type-C mux and switch devices. This provides the necessary
> support for enabling the DisplayPort altmode on devices with this
> circuit.

...

> +static const struct regmap_config fsa4480_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .max_register = FSA4480_MAX_REGISTER,
> +};

You are using mutex for accessing hardware. Do you still need a regmap lock?
If so, add a comment to explain why.

...

> + /* 15us to allow the SBU switch to turn off */
> + usleep_range(15, 1000);

This is quite unusual range.

If you are fine with the long delay, why to stress the system on it?
Otherwise the use of 1000 is unclear.

That said, I would expect one of the below:

usleep_range(15, 30);
usleep_range(500, 1000);

...

> + sw_desc.fwnode = dev->fwnode;

Please, don't dereference for fwnode explicitly. Use dev_fwnode().

...

> + mux_desc.fwnode = dev->fwnode;

Ditto.

--
With Best Regards,
Andy Shevchenko