Re: [PATCH v3] HID: i2c-hid: Always sleep 60ms after I2C_HID_PWR_ON commands

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On Tue, 11 Aug 2020, Hans de Goede wrote:

> Before this commit i2c_hid_parse() consists of the following steps:
> 
> 1. Send power on cmd
> 2. usleep_range(1000, 5000)
> 3. Send reset cmd
> 4. Wait for reset to complete (device interrupt, or msleep(100))
> 5. Send power on cmd
> 6. Try to read HID descriptor
> 
> Notice how there is an usleep_range(1000, 5000) after the first power-on
> command, but not after the second power-on command.
> 
> Testing has shown that at least on the BMAX Y13 laptop's i2c-hid touchpad,
> not having a delay after the second power-on command causes the HID
> descriptor to read as all zeros.
> 
> In case we hit this on other devices too, the descriptor being all zeros
> can be recognized by the following message being logged many, many times:
> 
> hid-generic 0018:0911:5288.0002: unknown main item tag 0x0
> 
> At the same time as the BMAX Y13's touchpad issue was debugged,
> Kai-Heng was working on debugging some issues with Goodix i2c-hid
> touchpads. It turns out that these need a delay after a PWR_ON command
> too, otherwise they stop working after a suspend/resume cycle.
> According to Goodix a delay of minimal 60ms is needed.
> 
> Having multiple cases where we need a delay after sending the power-on
> command, seems to indicate that we should always sleep after the power-on
> command.
> 
> This commit fixes the mentioned issues by moving the existing 1ms sleep to
> the i2c_hid_set_power() function and changing it to a 60ms sleep.

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs




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