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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 036CBC7EE26 for ; Mon, 22 May 2023 12:00:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233710AbjEVMAy (ORCPT ); Mon, 22 May 2023 08:00:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233645AbjEVL7z (ORCPT ); Mon, 22 May 2023 07:59:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 468A6100; Mon, 22 May 2023 04:59:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 222DB6135D; Mon, 22 May 2023 11:59:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83D25C433EF; Mon, 22 May 2023 11:59:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684756776; bh=noLNVGz2jJ7O7o4ac5on++xmXX/K/ni7BD/UCTe0wmM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H+zjQstKzirDiOEWd50KK6ocVionxHN0tfFF9k6+xTfxZxsNBCmbTglBCdUhrNdyY +n83SPrjEYrFQW5NJXpZ0U4+TCf1nnEjsLTRO9ag4IIOCl59tFi2kDTdRc/vp9rSoI OwX8FePZJpGZB9/OZEGOVw5uyp+yHidwL25L6RDEF/GzHtlQsPdg/F+HvO6Lkom7al D2c/LkXnEfD5yPtY83mgeF8CwwyYvuKaL5RY8FABjPJoUYshGHVY8aVr+CTs0/2h1o vzLzZ4n6j4W3op1CUIcl5mNMyCDp/9jiqp+njaZBgWLfBy235wH8PtPhznPRwk5tOt 0bjelTZX/FE5g== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1q14CO-0001dA-JB; Mon, 22 May 2023 13:59:37 +0200 Date: Mon, 22 May 2023 13:59:36 +0200 From: Johan Hovold To: Corey Minyard Cc: Craig Shelley , Linux Kernel , linux-usb@vger.kernel.org Subject: Re: Break doesn't work on a CP2105 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Corey, and sorry about the late reply on this. On Wed, Apr 26, 2023 at 03:04:03PM -0500, Corey Minyard wrote: > I have a development board with a CP2105 on it, and I was trying to send > a break to it to do a sysrq. And it wasn't working. > > I have verified that the target driver works by setting a really slow > baud rate and sending something with a lot of zero bits. It got breaks > just fine. > > If I use TCSBRK, it seems to just send a short time with zeros, not > even a full character's worth. It receives a valid character with the > top few bits set. If I use TCSBRKP with a longer time, like 2.5 > seconds, it waits the whole time, then at the very end it gets the > character as with the shorter break. > > I can't find a programming manual for the chip, and I'm not sure what's > going on. I just verified that break works on the first port of my cp2105 but not on the second one (I seem to receive the last characters sent instead). Apparently this is expected as the datasheet (AN571) says the following about the SET_BREAK command: This command is not supported on the second CP2105 interface. Which port are you seeing this behaviour with? Johan