Re: [PATCH v2] hwmon: Add driver for MSI Mystic Light controller voltage sensors

[Tomasz Bojanowski <tomasz@bojanowski.me>]

Hi Guenter,

On 11/7/26 10:02, Guenter Roeck wrote:
> What am I missing ?

Sorry, my earlier description was not clear about how the request is
sent. From the vendor software, it looks like this:

- The request goes out as an output report with report ID 0xfa, not
  as a feature report. If I read usbhid_set_raw_report() correctly,
  it puts reportnum into buf[0], so with MSI_ML_SENSOR_REPORT_ID the
  controller would have received a feature report 0xf0 instead.
- The reply seems to come back as an input report on the interrupt
  endpoint, not through GET_REPORT. As long as the driver calls
  hid_hw_open(), it should show up in .raw_event().

Roughly like this (untested, I have none of these boards):

        buf[0] = 0xfa;
        buf[1] = 0xa0;
        buf[9] = 0x01;
        buf[10] = 0xfc;
        reinit_completion(&priv->done);
        ret = hid_hw_output_report(hdev, buf, 64);
        if (ret == -ENOSYS)
                ret = hid_hw_raw_request(hdev, 0xfa, buf, 64,
                                         HID_OUTPUT_REPORT,
                                         HID_REQ_SET_REPORT);
        ...
        wait_for_completion_timeout(&priv->done, msecs_to_jiffies(500));

In .raw_event(), the reply could be accepted when data[0] == 0xfa,
data[2] == 0x01 and size == 64, followed by complete().

The report ID should stay a constant 0xfa: with 0x01, the same buffer
would be the bootloader command.

A quicker check might be to write the 64 bytes to the hidraw node and
read() the input reports.

Thanks,
Tomasz