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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=NLThGLGX2luBPY/V3tzpyvjSzQN5EJNand59KMNVjgc=; b=ISCv+RYBFT5lOJ6Uk/FL2kUQOexm+NRlqofha7yQCmA6nPJk0eraOB77NJxKyb09Kr sMyC6UppVUivbz44h1eLkS5O9xv4S72+nS/Pgh90ZPI/Dhj9avGWxkxXugRrFw+DIobo AuYu15TnqzoR7mVkEpAENRIbO/gCZHcMDxEao8FFC050hPfE0fhFsb3sKxaCMDaqVzkx EBUSJFaseMx8cTpoEVHcOCUnRV3nxRcpZlEX5rdR8//pK3W9zl5zCfVLHrOt5zlSohdU cm/URrScTVBoY177iOwIqkaa01AAe4BUD0nfPFvrKQ/aVAuSGtQgYzRIzvfkAZ+PMDJD I5sw== X-Gm-Message-State: APjAAAXBJJ7kwv+f8mSH2JjirmN5fcINN4jgTKGsrCFbWQwq8Q8QTKpZ bI/e5YtI2ug/BenaBDF01OC2ee6n+y2t3yuM9Kc= X-Google-Smtp-Source: APXvYqwUhkAPW9D2SkLS1McuAXKVB3YjfihtVnFvJQvIuEmwcKR9GEFxQHz+6tPz/KYnEI/dqNUstw+dR+4k3wO1i98= X-Received: by 2002:a19:2207:: with SMTP id i7mr28348579lfi.185.1568302273356; Thu, 12 Sep 2019 08:31:13 -0700 (PDT) MIME-Version: 1.0 References: <20190911144943.21554-1-philipp.puschmann@emlix.com> In-Reply-To: <20190911144943.21554-1-philipp.puschmann@emlix.com> From: Fabio Estevam Date: Thu, 12 Sep 2019 12:31:02 -0300 Message-ID: Subject: Re: [PATCH 0/4] Fix UART DMA freezes for iMX6 To: Philipp Puschmann , Robin Gong , Fugang Duan X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190912_083115_914106_2531022E X-CRM114-Status: GOOD ( 16.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-serial@vger.kernel.org, Greg Kroah-Hartman , Sascha Hauer , linux-kernel , Vinod , NXP Linux Team , Sascha Hauer , Jiri Slaby , dmaengine@vger.kernel.org, Dan Williams , Shawn Guo , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org [Adding Robin and Andy] On Wed, Sep 11, 2019 at 11:50 AM Philipp Puschmann wrote: > > For some years and since many kernel versions there are reports that > RX UART DMA channel stops working at one point. So far the usual workaround was > to disable RX DMA. This patches try to fix the underlying problem. > > When a running sdma script does not find any usable destination buffer to put > its data into it just leads to stopping the channel being scheduled again. As > solution we we manually retrigger the sdma script for this channel and by this > dissolve the freeze. > > While this seems to work fine so far a further patch in this series increases > the number of RX DMA periods for UART to reduce use cases running into such > a situation. > > This patch series was tested with the current kernel and backported to > kernel 4.15 with a special use case using a WL1837MOD via UART and provoking > the hanging of UART RX DMA within seconds after starting a test application. > It resulted in well known > "Bluetooth: hci0: command 0x0408 tx timeout" > errors and complete stop of UART data reception. Our Bluetooth traffic consists > of many independent small packets, mostly only a few bytes, causing high usage > of periods. > > > Philipp Puschmann (4): > dmaengine: imx-sdma: fix buffer ownership > dmaengine: imx-sdma: fix dma freezes > serial: imx: adapt rx buffer and dma periods > dmaengine: imx-sdma: drop redundant variable > > drivers/dma/imx-sdma.c | 32 ++++++++++++++++++++++---------- > drivers/tty/serial/imx.c | 5 ++--- > 2 files changed, 24 insertions(+), 13 deletions(-) > > -- > 2.23.0 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel