Re: [PATCH V2 1/1] USB: serial: f81232: fix incomplete serial port generation

[Johan Hovold <johan@kernel.org>]

On Tue, Dec 02, 2025 at 01:40:28PM +0800, Peter Hong wrote:
> Hi,
> 
> Johan Hovold 於 2025/12/1 下午 09:38 寫道:
> > On Fri, Nov 28, 2025 at 04:52:44PM +0800, Ji-Ze Hong (Peter Hong) wrote:
> >> The Fintek F81532A/534A/535/536 family relies on the
> >> F81534A_CTRL_CMD_ENABLE_PORT (116h) register during initialization to
> >> both determine serial port status and control port creation. If the
> >> driver experiences fast load/unload cycles, the device state may becomes
> >> unstable, resulting in the incomplete generation of serial ports.
> >>
> >> Performing a dummy read operation on the register prior to the initial
> >> write command resolves the issue. This clears the device's stale internal
> >> state. Subsequent write operations will correctly generate all serial
> >> ports.

> > Did you try removing the retry loop also in the set_register() helper?
> > Perhaps that's no longer needed after the dummy read.
> 
> I will try removing the retry loop in set_register() helper.
> If that worked, could I use the same patch file or series of patches?

I think you can do it in one patch since I assume the existing retry
loop is there to work around the same underlying issue.

Johan