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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 ABCF1C47257 for ; Fri, 8 May 2020 17:31:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8074E218AC for ; Fri, 8 May 2020 17:31:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588959098; bh=WRzoALlV7ZN2GHdbZQhsE+HYWowuvtNz9dMDDXuhI88=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=n206SRUc95VyykMsrnR0u0DAdxkBovQZeW6Ff0SJQ++fqAZTipC9thFs7eIEpboqs 69WIWVTKRGwwhfhQYsPDtkG0CzF1E7d+JSKq8rXaI95cyDec+1yYVfyFXXQKVtMwL7 NEw9nrIpm/OTd7VLUJq3U/66W63bsLCIc7Q6i3t4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727099AbgEHRbh (ORCPT ); Fri, 8 May 2020 13:31:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:32964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726746AbgEHRbh (ORCPT ); Fri, 8 May 2020 13:31:37 -0400 Received: from localhost (fw-tnat.cambridge.arm.com [217.140.96.140]) (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 24F0E2184D; Fri, 8 May 2020 17:31:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588959096; bh=WRzoALlV7ZN2GHdbZQhsE+HYWowuvtNz9dMDDXuhI88=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=N5naS5m/e40q+uLMWZT2ttFDa7TnLxzUiR71erzt4j7XYt5I6AOb2wMcM6kEGONTP hw8OrJzgPzqmGwSbg9tIvYEwaV4mFe55M5HRNvvpzJrdEEnnbI7Smr1TNaGoHC8m6a YH64UJVl1r2J0MtcG5ZYmGVX5V3q/ct1aI5IAh1I= Date: Fri, 8 May 2020 18:31:34 +0100 From: Mark Brown To: Serge Semin Cc: Serge Semin , Georgy Vlasov , Ramil Zaripov , Alexey Malahov , Thomas Bogendoerfer , Paul Burton , Ralf Baechle , Arnd Bergmann , Allison Randal , Andy Shevchenko , Gareth Williams , Rob Herring , linux-mips@vger.kernel.org, devicetree@vger.kernel.org, Greg Kroah-Hartman , Thomas Gleixner , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/17] spi: dw: Clear DMAC register when done or stopped Message-ID: <20200508173134.GP4820@sirena.org.uk> References: <20200508132943.9826-1-Sergey.Semin@baikalelectronics.ru> <20200508132943.9826-9-Sergey.Semin@baikalelectronics.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="BnCwdHgQ2ZomtW9r" Content-Disposition: inline In-Reply-To: <20200508132943.9826-9-Sergey.Semin@baikalelectronics.ru> X-Cookie: Give him an evasive answer. User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --BnCwdHgQ2ZomtW9r Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, May 08, 2020 at 04:29:33PM +0300, Serge Semin wrote: > If DMAC register is left uncleared any further DMAless transfers > may cause the DMAC hardware handshaking interface getting activated. > So the next DMA-based Rx/Tx transaction will be started right > after the dma_async_issue_pending() method is invoked even if no > DMATDLR/DMARDLR conditions are met. This at the same time may cause > the Tx/Rx FIFO buffers underrun/overrun. In order to fix this we > must clear DMAC register after a current DMA-based transaction is > finished. This also looks like a bugfix so should be pulled forwards to the start of the series if possible. --BnCwdHgQ2ZomtW9r Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl61l3UACgkQJNaLcl1U h9BYHgf9Fl+KkM9DAYgx9AGChw/IYpN7v0C5DO9u46ti7pzCXkna45nllKWyJ+W6 /IBw7tAETN0X3Oeg7yrgik/DAKX58MapNxW3Iq3iYa/RBX/2Lkxqb441hmmNFgOp g8lI/G8gh9WkKF1E7lVqqBScEwiRbGDWTHWM2WuYSr8mAnK5FL+HLvF5YQKvAcHm 1TD3/v8ckN2iTXWH8IWjBdqJI7Y+2TXXz1Xr13/laIDvDq51xtJk0YXUstdLcSnq sPwjaTA+RTDZKCa2NsFKx04M3JYrJMIq8YjAoCjhKOKBJf3EaJ/EalmfaTucfs0O NwU9G+7xV1+6hlkILdXn+sStvR7LTQ== =TR5g -----END PGP SIGNATURE----- --BnCwdHgQ2ZomtW9r--