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charset=utf-8 Content-Transfer-Encoding: 8bit Fabio Estevam writes: > On Fri, Apr 5, 2024 at 6:25 AM Esben Haabendal wrote: >> >> By waiting at most 1 second for USR2_TXDC to be set, we avoid a potentital > > s/potentital/potential > > Could you elaborate on this deadlock? Have you seen it in practice? I've stumped upon this piece of code a long time ago, and it's indeed broken. However, to actually see a "deadlock", I believe one needs to enable hardware RTS/CTS handshake on the port, then, say, not connect RS232 cable, and then printk(), if enabled to this port, will soon result in the loop to be executed forever, that in turn will hang single-CPU machine entirely (provided this code is still executed with interrupts disabled, as it was at the time I investigated severe printk()-induced ISR delays). -- Sergey Organov From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 80A13CD11C2 for ; Fri, 5 Apr 2024 19:06:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; 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Fri, 05 Apr 2024 12:06:00 -0700 (PDT) From: Sergey Organov To: Fabio Estevam Cc: Esben Haabendal , Greg Kroah-Hartman , Jiri Slaby , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Marc Kleine-Budde , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 1/2] serial: imx: Introduce timeout when waiting on transmitter empty References: <76cf9ce9cbf9dcdf78bc00ce7a919db1776ebce1.1712309058.git.esben@geanix.com> Date: Fri, 05 Apr 2024 22:05:59 +0300 In-Reply-To: (Fabio Estevam's message of "Fri, 5 Apr 2024 14:38:48 -0300") Message-ID: <87r0fj1vfs.fsf@osv.gnss.ru> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240405_120604_326849_F7879F0D X-CRM114-Status: GOOD ( 10.93 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; 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