Re: [PATCH v3 13/16] HID: ft260: i2c: reject an I2C clock outside the supported range

[sashiko-bot@kernel.org]

> The clock sysfs attribute passes any 16-bit value to the chip. The chip
> accepts it, reports it back in the I2C status report that clock_show
> reads, and runs the bus at the 100 kHz default. A read of 2048 bytes
> takes the same 0.298 s after writing 50, 3500 or 65535 as it does after
> writing 100, while 60 and 3400 give 0.387 s and 0.058 s. Userspace has
> no way to see that the value was not applied.
> 
> Refuse a value outside the 60-3400 kHz range named in the datasheet
> section 4.4.16. ft260_uart_change_speed() checks the baud rate against
> FT260_UART_CFG_BAUD_MIN and FT260_UART_CFG_BAUD_MAX, but termios has no
> error return, so it falls back to 9600. A sysfs store can return an
> error, so the clock store refuses the value.
> 
> FT260_WORD_ATTR_STORE() takes the parse function as a parameter now, so
> a word attribute with no range of its own keeps passing kstrtou16.
> 
> 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=13