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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 7DB26C433E1 for ; Mon, 8 Jun 2020 23:58:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FC7520737 for ; Mon, 8 Jun 2020 23:58:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591660689; bh=DJ2F7ivv8tQYyr+wv76RB0/v0aC81S0HThsE5JGpJ+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NG1ftxq7acV1wHYKMKW9XvnBNHGs7Y1EJemElu0Kiy7BGQBOjTM3gaMvZMawHKWTR pI5K9QIx9E5vK2kaFx1y2MSlAXK/P6c0eJQ/1brnG+Z45zERdfkGn9596lY3ujz6VL jpWjxqvSSkThzITl/Xa3zGUnddQVdm/jAndWqLs8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731468AbgFHXXS (ORCPT ); Mon, 8 Jun 2020 19:23:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:48400 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731464AbgFHXXP (ORCPT ); Mon, 8 Jun 2020 19:23:15 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 619CB20897; Mon, 8 Jun 2020 23:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658594; bh=DJ2F7ivv8tQYyr+wv76RB0/v0aC81S0HThsE5JGpJ+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LZpHpgpwWIdV+0Uno2geUJ5GcLVrLW72mLY/qsV+bGFSyUjxh17lcO6bDEvSWvGyv Gilm0kin11R8ukpgxcRMLV4M+AOx1QT8+Od6LKjfqufg9VKrcDZ7xj+1vWA1QY+A+c vzNKB1s4RROJCKgpIBmeH8xhfVaRlqC3LHDXGlhg= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Serge Semin , Andy Shevchenko , Georgy Vlasov , Ramil Zaripov , Alexey Malahov , Thomas Bogendoerfer , Arnd Bergmann , Feng Tang , Rob Herring , linux-mips@vger.kernel.org, devicetree@vger.kernel.org, Mark Brown , Sasha Levin , linux-spi@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 027/106] spi: dw: Fix Rx-only DMA transfers Date: Mon, 8 Jun 2020 19:21:19 -0400 Message-Id: <20200608232238.3368589-27-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200608232238.3368589-1-sashal@kernel.org> References: <20200608232238.3368589-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org From: Serge Semin [ Upstream commit 46164fde6b7890e7a3982d54549947c8394c0192 ] Tx-only DMA transfers are working perfectly fine since in this case the code just ignores the Rx FIFO overflow interrupts. But it turns out the SPI Rx-only transfers are broken since nothing pushing any data to the shift registers, so the Rx FIFO is left empty and the SPI core subsystems just returns a timeout error. Since DW DMAC driver doesn't support something like cyclic write operations of a single byte to a device register, the only way to support the Rx-only SPI transfers is to fake it by using a dummy Tx-buffer. This is what we intend to fix in this commit by setting the SPI_CONTROLLER_MUST_TX flag for DMA-capable platform. Signed-off-by: Serge Semin Reviewed-by: Andy Shevchenko Cc: Georgy Vlasov Cc: Ramil Zaripov Cc: Alexey Malahov Cc: Thomas Bogendoerfer Cc: Arnd Bergmann Cc: Feng Tang Cc: Rob Herring Cc: linux-mips@vger.kernel.org Cc: devicetree@vger.kernel.org Link: https://lore.kernel.org/r/20200529131205.31838-9-Sergey.Semin@baikalelectronics.ru Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-dw.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index 5a47e28e38c1..2207bf17f6a6 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -530,6 +530,7 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws) dws->dma_inited = 0; } else { master->can_dma = dws->dma_ops->can_dma; + master->flags |= SPI_CONTROLLER_MUST_TX; } } -- 2.25.1