Re: [PATCH v3 12/16] HID: ft260: i2c: abort in-flight transfers with STOP before reset

[sashiko-bot@kernel.org]

> A transfer that ends without STOP leaves the FT260 I2C controller
> with BUS_BUSY set. I2C reset (AN_394 section 4.4.15) restarts the
> master but, with the driver still bound, status stays 0x60
> (CTRL_IDLE | BUS_BUSY) even when SCL and SDA are pulled up. The
> next START then fails with 0x72 (arbitration lost + error) and
> further resets do not recover; only a USB replug did.
> 
> Add ft260_i2c_abort(): a STOP-only write (flag 0x04, zero payload)
> then FT260_SET_I2C_RESET. Use it wherever the host tears down an
> open transaction:
> 
>   - read wait timeout
>   - read status check failure after the HID report arrived
>   - write status poll failure after the report was sent
>   - SMBus block read with an invalid count (count phase has no STOP)
> 
> Leave ft260_i2c_reset() alone for HID output failure (the request
> may never have reached the controller), sysfs i2c_reset, and probe.
> 
> Tested on a UMFT260EV1A with a 24LC512 at 0x51. Five 1 ms read
> timeouts each followed by STOP+reset left bus_status 0x20; raising
> the timeout to 25 ms on the same loaded module then read 16 bytes
> successfully.
> 
> This matters more with the 25/75 ms completion timeout from
> "HID: ft260: i2c: reduce driver module loading time", which makes
> read timeouts more likely than mainline's 5000 ms wait.
> 
> Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261114230800.1344401-1-michael.zaidman@gmail.com?part=12