From patchwork Wed Mar 15 19:37:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 9626525 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 1125F604A9 for ; Wed, 15 Mar 2017 19:37:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 045272793A for ; Wed, 15 Mar 2017 19:37:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ED5802838E; Wed, 15 Mar 2017 19:37:31 +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=ham 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 6B4DD2793A for ; Wed, 15 Mar 2017 19:37:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752874AbdCOThb (ORCPT ); Wed, 15 Mar 2017 15:37:31 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:56092 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751358AbdCOThb (ORCPT ); Wed, 15 Mar 2017 15:37:31 -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 1coEja-0000Nz-Kj; Wed, 15 Mar 2017 19:37:24 +0000 Received: from broonie by debutante with local (Exim 4.88) (envelope-from ) id 1coEjX-0004ho-PR; Wed, 15 Mar 2017 19:37:19 +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: <1487327904-28311-4-git-send-email-fisaksen@baylibre.com> Message-Id: Date: Wed, 15 Mar 2017 19:37:19 +0000 X-SA-Exim-Connect-IP: 2001:470:1f1d:6b5::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Applied "spi: davinci: use rx buffer as dummy tx buffer" 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: use rx buffer as dummy tx buffer 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 6b3a631e7f8eca75a987ed760898d28fb3628143 Mon Sep 17 00:00:00 2001 From: Frode Isaksen Date: Thu, 23 Feb 2017 19:01:58 +0100 Subject: [PATCH] spi: davinci: use rx buffer as dummy tx buffer When doing rx-only transfer, the transfer will fail if the number of SG entries exceeds 20. This happens because the eDMA DMA engine is limited to 20 SG entries in one transaction, and when the DMA transcation is resumed (which takes > 150us), rx errors occurs because the slave is still transmitting. Fix this by using the rx buffer as the dummy tx buffer, so that resuming the rx transcation happens at the same time as resuming the tx transcation. Signed-off-by: Frode Isaksen Signed-off-by: Mark Brown --- drivers/spi/spi-davinci.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c index 1e24395a04f2..ca122165a3c6 100644 --- a/drivers/spi/spi-davinci.c +++ b/drivers/spi/spi-davinci.c @@ -655,6 +655,12 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) if (!rxdesc) goto err_desc; + if (!t->tx_buf) { + /* use rx buffer as dummy tx buffer */ + t->tx_sg.sgl = t->rx_sg.sgl; + t->tx_sg.nents = t->rx_sg.nents; + } + txdesc = dmaengine_prep_slave_sg(dspi->dma_tx, t->tx_sg.sgl, t->tx_sg.nents, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); @@ -957,7 +963,7 @@ static int davinci_spi_probe(struct platform_device *pdev) master->bus_num = pdev->id; master->num_chipselect = pdata->num_chipselect; master->bits_per_word_mask = SPI_BPW_RANGE_MASK(2, 16); - master->flags = (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX); + master->flags = SPI_MASTER_MUST_RX; master->setup = davinci_spi_setup; master->cleanup = davinci_spi_cleanup; master->can_dma = davinci_spi_can_dma;