linux-kernel - Re: [PATCH V3 1/1] USB: serial: f81232: fix incomplete serial port generation

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Message-ID: <aWZfGgQx6HXglmXX@hovoldconsulting.com>
Date: Tue, 13 Jan 2026 16:04:58 +0100
From: Johan Hovold <johan@...nel.org>
To: "Ji-Ze Hong (Peter Hong)" <peter_hong@...tek.com.tw>
Cc: hpeter+linux_kernel@...il.com, gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	tom_tsai@...tek.com.tw, yu_chen@...tek.com.tw
Subject: Re: [PATCH V3 1/1] USB: serial: f81232: fix incomplete serial port
 generation

On Fri, Dec 12, 2025 at 03:08:31PM +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.
> 
> This patch also removes the retry loop in f81534a_ctrl_set_register()
> because the stale state has been fixed.
> 
> Tested on: HygonDM1SLT(Hygon C86 3250 8-core Processor)
> 
> Signed-off-by: Ji-Ze Hong (Peter Hong) <peter_hong@...tek.com.tw>
> ---

Next time, please remember to include a short changelog here under the
cut off line (---).

Now applied, thanks.

Johan