Re: Post-facto backport request: USB: serial: f81232: fix incomplete serial port generation

[Johan Hovold <johan@kernel.org>]

Hi Peter,

On Wed, Mar 18, 2026 at 08:46:28AM +0800, PS10 PETER HONG 洪繼澤 wrote:
> Johan Hovold 於 2026/3/17 下午 03:22 寫道:
> > On Tue, Mar 17, 2026 at 10:21:17AM +0800, PS10 PETER HONG 洪繼澤 wrote:

> >> I would like to request a backport for the following commit to the
> >> currently supported stable trees 6.1.y, 6.6.y, 6.12.y and 6.18.y
> >>
> >>     cd644b805da8 ("USB: serial: f81232: fix incomplete serial port
> >> generation")
> >>
> >> Reason:
> >>     This patch fixes a stability issue where Fintek F81532A/534A/535/536
> >>     devices fail to initialize all serial ports during fast load/unload
> >> cycles.
> >>     The fix involves a dummy read to clear the device's stale internal state.

> Typical users are unlikely to encounter this, but one of our customers is
> currently facing the issue. They have requested that we submit this patch to
> the stable tree so they can utilize the mainstream driver without needing a
> separate vendor driver.
> 
> In theory, applying this patch will improve the product's overall stability.
> We would like to see this integrated into the mainstream kernel tree.

Sounds good.

Johan