From patchwork Fri Mar 17 22:01:10 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 9631695 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CA1E660249 for ; Fri, 17 Mar 2017 22:02:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AF79126E4F for ; Fri, 17 Mar 2017 22:02:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A24CC2808F; Fri, 17 Mar 2017 22:02:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 30A9726E4F for ; Fri, 17 Mar 2017 22:02:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751195AbdCQWCN (ORCPT ); Fri, 17 Mar 2017 18:02:13 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:44540 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751061AbdCQWCM (ORCPT ); Fri, 17 Mar 2017 18:02:12 -0400 Received: from [2001:470:1f1d:6b5::3] (helo=debutante) by mezzanine.sirena.org.uk with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1cozvt-0004xn-B9; Fri, 17 Mar 2017 22:01:15 +0000 Received: from broonie by debutante with local (Exim 4.88) (envelope-from ) id 1cozvq-0002ly-L9; Fri, 17 Mar 2017 22:01:10 +0000 From: Mark Brown To: Frode Isaksen Cc: Mark Brown , nsekhar@ti.com, khilman@baylibre.com, ptitiano@baylibre.com, linux-arm-kernel@lists.infradead.org, broonie@kernel.org, linux-spi@vger.kernel.org, linux-spi@vger.kernel.org In-Reply-To: <1489765270-17950-1-git-send-email-fisaksen@baylibre.com> Message-Id: Date: Fri, 17 Mar 2017 22:01:10 +0000 X-SA-Exim-Connect-IP: 2001:470:1f1d:6b5::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Applied "spi: davinci: add comment about dummy tx buffer usage" to the spi tree X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: No (on mezzanine.sirena.org.uk); Unknown failure Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The patch spi: davinci: add comment about dummy tx buffer usage has been applied to the spi tree at git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark From 1234e8398fe03267bf2e353e36825dbd0abc2fc6 Mon Sep 17 00:00:00 2001 From: Frode Isaksen Date: Fri, 17 Mar 2017 16:41:10 +0100 Subject: [PATCH] spi: davinci: add comment about dummy tx buffer usage Add explanation about using the the rx buffer as the dummy tx buffer. Signed-off-by: Frode Isaksen Signed-off-by: Mark Brown --- drivers/spi/spi-davinci.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c index f37bbdd18d61..595acdcfc7d0 100644 --- a/drivers/spi/spi-davinci.c +++ b/drivers/spi/spi-davinci.c @@ -660,7 +660,11 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) goto err_desc; if (!t->tx_buf) { - /* use rx buffer as dummy tx buffer */ + /* To avoid errors when doing rx-only transfers with + * many SG entries (> 20), use the rx buffer as the + * dummy tx buffer so that dma reloads are done at the + * same time for rx and tx. + */ t->tx_sg.sgl = t->rx_sg.sgl; t->tx_sg.nents = t->rx_sg.nents; }