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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB5E8C433E0 for ; Thu, 2 Jul 2020 07:37:28 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A8AAE20899 for ; Thu, 2 Jul 2020 07:37:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ZnOz5mMo"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="KmcMFIrP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A8AAE20899 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lizkPHIEjZmhrZcaN/IJ3ZeES4B2ka5zFs9I0VZgE5o=; b=ZnOz5mMoWXJwO5yAPxsHevpX0 +JaG1gsGLE8jVth/n7qM4YZXpEPIiK6a/rAO9oqR8/MKXHlRxAHJ7y5zN7qDPdgbOmMjrbGSnWXuz rlGe8X63PCdGhZ6iKidWMyh54B8CQNG+hZUWGQI+PqVu+/0e9+RPYxMBa3HdmZQi/Ybl8/0rczjor yNkxi7w8S+zJf0NcIBmA3aOyXUcgauwgzriMZeJ3AK30jmTCTU9t2U8VdCUdTIXVvf97MapIj/RKV h84EdZbakQfS/1fVJUT6oLZmJ/PZd/mCVy6/FrUxp+ppz6jDWbVDkJCop6uN3EIKs2cCPPWFLlCZ2 fMtsIyrjw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jqtmZ-0008AL-AQ; Thu, 02 Jul 2020 07:37:19 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jqtmW-00089g-Pw for linux-mediatek@lists.infradead.org; Thu, 02 Jul 2020 07:37:17 +0000 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8A27F2085B; Thu, 2 Jul 2020 07:37:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593675436; bh=vpifWVwgbjHSUaEegAAHzDiKupI4P46wI+RPjm/wU9M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KmcMFIrPlH/DYGVA69kjk8PKCY/DCTSfxA7mi8F7SUmgwxhtcI3ae4CZwpCU359bq O48jck5Plf9ZR0KbrKdFvmTivRigbjS7x7dcIjocdZd0fcyNBPP6IoFm28o+ZJ2gwT rN71msrjI6cYKrnS0UT2QSDl1Lxr4H8miKM1euLk= Date: Thu, 2 Jul 2020 09:37:20 +0200 From: Greg Kroah-Hartman To: Serge Semin Subject: Re: [PATCH v2 0/1] Revert "serial: 8250: Fix max baud limit in generic 8250 port" Message-ID: <20200702073720.GE1073011@kroah.com> References: <20200701211337.3027448-1-danielwinkler@google.com> <20200701223713.gavale4aramu3xnb@mobilestation> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200701223713.gavale4aramu3xnb@mobilestation> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200702_033716_936940_D151C0DC X-CRM114-Status: GOOD ( 23.44 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: chromeos-bluetooth-upstreaming , Vignesh Raghavendra , Jiri Slaby , linux-kernel@vger.kernel.org, Serge Semin , Alexey Malahov , BlueZ , Lukas Wunner , linux-mediatek@lists.infradead.org, stable@vger.kernel.org, linux-serial@vger.kernel.org, Daniel Winkler , abhishekpandit@chromium.org, Aaron Sierra , Andy Shevchenko Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On Thu, Jul 02, 2020 at 01:37:13AM +0300, Serge Semin wrote: > On Wed, Jul 01, 2020 at 02:13:36PM -0700, Daniel Winkler wrote: > > > > This change regresses the QCA6174A-3 bluetooth chip, preventing > > firmware from being properly loaded. Without this change, the > > chip works as intended. > > > > The device is the Kukui Chromebook using the Mediatek chipset > > and the 8250_mtk uart. Initial controller baudrate is 115200 > > and operating speed is 3000000. Our entire suite of bluetooth > > tests now fail on this platform due to an apparent failure to > > sync its firmware on initialization. > > Ok. It's mediatek 8250 driver, which is responsible for the failure. > Then we'll have two options: > > 1) Add a new capability like UART_CAP_NO16DIV and take it into account > in the serial8250_get_baud_rate() method. > > I don't have a documentation for the Mediatek UART port, but it seems to me > that that controller calculates the baud rate differently from the standard > 8250 port. A standard 8250 port does that by the next formulae: > baud = uartclk / (16 * divisor). > While it seems to me that the Mediatek port uses the formulae like: > baud = uartclk / divisor. (Please, correct me if I'm wrong) > If so, then we could introduce a new capability like UART_CAP_NO16DIV. The > 8250_mtk driver will add it to the 8250-port capabilities field. The > serial8250_get_baud_rate() method should be altered in a way so one would check > whether the UART_CAP_NO16DIV flag is set and if it is then the > uart_get_baud_rate() function will be called without uartclk normalized by the > factor of 16. > > 2) Manually call serial8250_do_set_divisor() in the custom set_termios() > callback. > > Just add the uart_update_timeout() and serial8250_do_set_divisor() methods > invocation into the mtk8250_set_termios() function, which the original commit > 81bb549fdf14 ("serial: 8250_mtk: support big baud rate") author should have > done in the first place. Sounds like a sane fix, thanks for looking into this. greg k-h _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek