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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 46BA6C433E0 for ; Fri, 19 Jun 2020 15:07:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 206B121BE5 for ; Fri, 19 Jun 2020 15:07:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579247; bh=Ry7ffsonlHv7a5vi0afMmIH01N+u6fWs+CVFyp4Y7tE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bojONUZxF7o2G0spxj0EN/KQE+iwiWaiCFWNfVHlJUJgH1XPitwO7S8AFAWV4zxCu 4EXl6LhDeMRUv9oulYhx/tVvIG5CNZ8CAMWsyB+gmKv2Qkov7D+uFh0OOT1JGkf9+h URC86x9yW6s2ASC4T4NwCrvAUTuK/BmlbwgaTk9c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391577AbgFSPHZ (ORCPT ); Fri, 19 Jun 2020 11:07:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:36282 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391523AbgFSPHE (ORCPT ); Fri, 19 Jun 2020 11:07:04 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 4548621835; Fri, 19 Jun 2020 15:07:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579224; bh=Ry7ffsonlHv7a5vi0afMmIH01N+u6fWs+CVFyp4Y7tE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=14UOJBFBXzyfdWAyPQQ/4omCx0CJDYaIUkRMciZvAlSkCGpUu3C3B3xedhDGcqTEq NNDV1D6QV6v0vtIS35ktp9zDB8yd4cJaldJt724PygROhkfRT0wo5ibVSkRNdKQ4zl NSvf3z3iCTRM8EAIha0kIrkqO5JVjBPjoBujP/3w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, 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 Subject: [PATCH 5.4 053/261] spi: dw: Fix Rx-only DMA transfers Date: Fri, 19 Jun 2020 16:31:04 +0200 Message-Id: <20200619141652.470882659@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141649.878808811@linuxfoundation.org> References: <20200619141649.878808811@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 82c5c027ec4c..07d1c170c657 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -529,6 +529,7 @@ 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