From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75EEC28B3E2; Wed, 3 Dec 2025 11:04:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764759867; cv=none; b=bHtfWUU/mRhCDXSN70k9RJDaESqnqojL7Hmfrkk5Q7DyxuqZpF451YdgeRTDlzBWU44pFmmtQJzGuBOHQ1VldmNlp9uw4e1Qp8AxNUlnsJyAq28FyGhKQyEnRVIjlLyQzFBZm1Yg8I5YvOIi6N4CVvlS8EZlcvKsLU6hLVx9T84= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764759867; c=relaxed/simple; bh=fEiHoE8rCXCQbcUWFC3JKbtYUMh1FdKN3RCiOgPsPYs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ln/vH7u80ao2CjyyaoaSs8Id1LcAagHvXZjNt4/Jze6AKvBFt2XxZekGxS6WCwEFFAFuePT+zFNAoFFnYoWFsfUNvYcn2bn2w4OdA22wogAYOickvXivj3L1hx9d8B+XbdUGLfJCpMcGAEA4FsvytoKqvuQxbiTv782H87/ZkSU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Dz36wuYI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Dz36wuYI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01A2EC4CEFB; Wed, 3 Dec 2025 11:04:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764759867; bh=fEiHoE8rCXCQbcUWFC3JKbtYUMh1FdKN3RCiOgPsPYs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Dz36wuYI5ceIIVU/NbuPRcdG1JJzhzGqraOC4nnpNIA4an8nj2m6SA9SLCmhu5tVS A8nrvOcvmzDU0SGirJRK5lCC/LEUSqCrS8/2YuZeAzlQhAjSKuasG9hQcd7+2K9q3j IW2561nKsdn5ZuLbNG2O1XajXZHiuWaNoC/j9+m4JyKas2ariNyYZGXWL+TVJLgG87 zpV7fsvIYfUoJ1pIo41ws8s3oLB6lWf18QmE9afBzxbd4AYRbjJZJ/CuX4vNchNl+R ocF5YwX+dA2cv7lWyEtntHPxeCPHi6vT+iAulMp4+xWCVY4t51SxS+8TO9K8PrN924 LPFks5B9v785g== Received: from johan by xi.lan with local (Exim 4.98.2) (envelope-from ) id 1vQkex-000000006eP-0FLj; Wed, 03 Dec 2025 12:04:35 +0100 Date: Wed, 3 Dec 2025 12:04:35 +0100 From: Johan Hovold To: Peter Hong Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, tom_tsai@fintek.com.tw, yu_chen@fintek.com.tw Subject: Re: [PATCH V2 1/1] USB: serial: f81232: fix incomplete serial port generation Message-ID: References: <20251128085244.14044-1-peter_hong@fintek.com.tw> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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