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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 EEA7CC10DCE for ; Mon, 16 Mar 2020 02:36:53 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C468A206EB for ; Mon, 16 Mar 2020 02:36:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Vy6jaCSo"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="HkEOIoae" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C468A206EB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=sUvQLnK2EFppCPHIXbRaFRLWbSGY+O/r/uTq9bMkBqY=; b=Vy6jaCSoxCIcYN +97QrAfjj5wWlq0PI3iqOsfPwyS7Of40npFekC8u5RJpvuMX/NkbfnYOtCfCod+aB09LlSuhGyOpj DnYwgIa1H9xLYJab9wKKJAhxBk8n0Edy0KiG1dKJeP03iRDYjvBVdFamZJslJvULr46XRL2L7bWNk lKdZS3CCKkOn6PBAU91atP4Rr1e7mFj/YcGulhorVWcW6QTVTENkyDGOYngL82RtQOlPx9ImScOJn QKR2dBrch7WsjMQR/HQwCM+mmw3Aq0rrYVu5qftSNMMij00kM5OlhhyG1KjOGHwpajZMSTg9739f8 MGbGAwmEf5+qdhBWaF8g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDfcZ-0005xO-18; Mon, 16 Mar 2020 02:36:51 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDfZU-0002J6-RN for linux-arm-kernel@lists.infradead.org; Mon, 16 Mar 2020 02:33:44 +0000 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 47CB420722; Mon, 16 Mar 2020 02:33:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584326019; bh=e0FJE4mmKOLy1FnSL5Kj2UeQ9zkdN+4VFJKPic2+/YI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HkEOIoaeF07JedlJPbadevlTgGT2iWUedMZXceW9cKLD5mYjAlu2YVSo/uXwMSiv+ N/6Y+mNWFdEk+uP9imVhtSIG30nIGdKhNYV7FmUO5r9xDaxz/UuaJsOOwpa6plCvO8 3NuUfL0Fs0yVavp75cKv1uqvvLdEPZfo9oLdyVJ4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 5.5 16/41] spi/zynqmp: remove entry that causes a cs glitch Date: Sun, 15 Mar 2020 22:32:54 -0400 Message-Id: <20200316023319.749-16-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200316023319.749-1-sashal@kernel.org> References: <20200316023319.749-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200315_193341_011382_20EC1DA5 X-CRM114-Status: GOOD ( 13.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sasha Levin , Naga Sureshkumar Relli , linux-spi@vger.kernel.org, Thommy Jakobsson , Mark Brown , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Thommy Jakobsson [ Upstream commit 5dd8304981ecffa77bb72b1c57c4be5dfe6cfae9 ] In the public interface for chipselect, there is always an entry commented as "Dummy generic FIFO entry" pushed down to the fifo right after the activate/deactivate command. The dummy entry is 0x0, irregardless if the intention was to activate or deactive the cs. This causes the cs line to glitch rather than beeing activated in the case when there was an activate command. This has been observed on oscilloscope, and have caused problems for at least one specific flash device type connected to the qspi port. After the change the glitch is gone and cs goes active when intended. The reason why this worked before (except for the glitch) was because when sending the actual data, the CS bits are once again set. Since most flashes uses mode 0, there is always a half clk period anyway for cs to clk active setup time. If someone would rely on timing from a chip_select call to a transfer_one, it would fail though. It is unknown why the dummy entry was there in the first place, git log seems to be of no help in this case. The reference manual gives no indication of the necessity of this. In fact the lower 8 bits are a setup (or hold in case of deactivate) time expressed in cycles. So this should not be needed to fulfill any setup/hold timings. Signed-off-by: Thommy Jakobsson Reviewed-by: Naga Sureshkumar Relli Link: https://lore.kernel.org/r/20200224162643.29102-1-thommyj@gmail.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-zynqmp-gqspi.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/spi/spi-zynqmp-gqspi.c b/drivers/spi/spi-zynqmp-gqspi.c index 60c4de4e44856..7412a3042a8d2 100644 --- a/drivers/spi/spi-zynqmp-gqspi.c +++ b/drivers/spi/spi-zynqmp-gqspi.c @@ -401,9 +401,6 @@ static void zynqmp_qspi_chipselect(struct spi_device *qspi, bool is_high) zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry); - /* Dummy generic FIFO entry */ - zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0); - /* Manually start the generic FIFO command */ zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST, zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST) | -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel