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[79.136.29.16]) by smtp.gmail.com with ESMTPSA id l3-v6sm1490962ljg.21.2019.01.25.03.44.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Jan 2019 03:44:34 -0800 (PST) From: Jonas Bonn To: linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Cc: Jonas Bonn , Nicolas Ferre , Mark Brown , Alexandre Belloni , Ludovic Desroches , linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/2] spi-atmel: support inter-word delay Date: Fri, 25 Jan 2019 12:44:29 +0100 Message-Id: <20190125114429.20066-3-jonas@norrbonn.se> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190125114429.20066-1-jonas@norrbonn.se> References: <20190125114429.20066-1-jonas@norrbonn.se> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the SPI slave requires an inter-word delay, configure the DLYBCT register accordingly. Tested on a SAMA5D2 board (derived from SAMA5D2-Xplained reference board). Signed-off-by: Jonas Bonn CC: Nicolas Ferre CC: Mark Brown CC: Alexandre Belloni CC: Ludovic Desroches CC: linux-spi@vger.kernel.org CC: linux-arm-kernel@lists.infradead.org --- drivers/spi/spi-atmel.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 74fddcd3282b..88ff3fef56e9 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -1209,13 +1209,14 @@ static int atmel_spi_setup(struct spi_device *spi) csr |= SPI_BIT(CSAAT); /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs. - * - * DLYBCT would add delays between words, slowing down transfers. - * It could potentially be useful to cope with DMA bottlenecks, but - * in those cases it's probably best to just use a lower bitrate. */ csr |= SPI_BF(DLYBS, 0); - csr |= SPI_BF(DLYBCT, 0); + + /* DLYBCT adds delays between words. This is useful for slow devices + * that need a bit of time to setup the next transfer. + */ + csr |= SPI_BF(DLYBCT, + clamp_t(u8, (as->spi_clk/1000000*spi->word_delay)>>5, 1, 255)); /* chipselect must have been muxed as GPIO (e.g. in board setup) */ npcs_pin = (unsigned long)spi->controller_data; -- 2.19.1 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,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 E1629C282C2 for ; Fri, 25 Jan 2019 11:44:44 +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 B0EAE218CD for ; Fri, 25 Jan 2019 11:44:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="OjAuu1we"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=norrbonn-se.20150623.gappssmtp.com header.i=@norrbonn-se.20150623.gappssmtp.com header.b="GEUhvkW0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0EAE218CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=norrbonn.se 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=JPW/I5L1stgJ1W4bLAveski9FT8DePaKoyyoDs9MD30=; b=OjAuu1weqmmtx9 cckXZHdpXNWDxLwjXUMt23Sx84DA4b6E1QpREpDI/H61qiduwPqQT8hZWUdhXiZ6rKkMHPnMhdGlS o98plw8qKW/4y3ZxLhcfu+Knv6VjoQqSLrMMa/i+h5TrhXOA7L//EWTgVisfQBB0uXs5R2sz2g4vW 2gx+k1BzOQjgmX+4zaOc0BxIXE2i0kNDmJwyot52MR+utHI37zbr8r/HMNSdm8bEaK5VRbbQr8yaH YXKPbWA0rSNAYWW8+BaxG0Ut+UE0LhpKd4aNXjhNRvOpb9vADHUNlZ9ae3+K3ozvUauORkfyMt+nu owx3dPQZVWzDs+RK4NtQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gmzua-0007c9-4x; Fri, 25 Jan 2019 11:44:40 +0000 Received: from mail-lj1-x243.google.com ([2a00:1450:4864:20::243]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gmzuW-0007bS-Qs for linux-arm-kernel@lists.infradead.org; Fri, 25 Jan 2019 11:44:38 +0000 Received: by mail-lj1-x243.google.com with SMTP id k15-v6so8097643ljc.8 for ; Fri, 25 Jan 2019 03:44:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=norrbonn-se.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Uu+GXREpN4UO7hWlKWeYJkb2H2GuTbzfegM7LkbZ/S8=; b=GEUhvkW0Aw6GHc3vSCXnmV8GTX+YAf3myHFSu3fzEAnbXvX5jP4hXHpfVi7RFjWnja elrrK7YvfIRcN9CgC/dZF3gn1rPhSfenaHc44zUrV1dK5Gl2X73Qp2C4YRSEWiyrJXYl ZErLRdaCPITbBF5zegxKL9TEv1aW3ySw7OiCPhQKLLJPLuw3ncrhK3VapBNZABn2IFKZ VEWtlB1mF61toNnCH8oEtzitthO/MpcHWX5gIyJyfqcLOEZpkLTVqrrrgL4rjQe962m8 /VKS6rDm++8Wdg1694dCdU/BOaExp+AHisTiVIFzbC8BBmVLmh0fD8k/4qNxrb2NNgeQ 3RIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Uu+GXREpN4UO7hWlKWeYJkb2H2GuTbzfegM7LkbZ/S8=; b=ExwimZFMJJRwctY1OuxQors5kY4saY5lvvfVL8njDrHG1nNQ7ZSBhOrcGgeS7mXjX5 UqLeuGxCCuLwm1wJ38JxypsABbxj4sB486rrQO3NCcNNCZMa9ntGJoUvTl5OGOPPm9Hj 0cJ4HoaszB79jbGJgPK9KGQjP6KLYc1V+nlBb17LVuk77fNfNxFV1JTA0eebtUrW2TW1 b6ac6oomtfNaGskqqpFvbNc7PyGIhL994RFhVbwy7XRB06NdsRqL7Iexuip2n4pHWIR8 QPGW5GCmi85X6uNItE4Wq/xuYw0qzQpgzlwPSHSM4siXR3A5zIFpFqrE+GFtx1Zxe/H0 6YFA== X-Gm-Message-State: AJcUukfjbEPgwUOKMXVNQnMvbP5I6pzTA0REmTGzU3/jJUAzqoBG4bX0 sHUkSK3gIdq0mzxCq245FLFxqQ== X-Google-Smtp-Source: ALg8bN6XRXLKpFi04wXl+PQPSrzZMHYzuhRqTgfnNVEGIcDJwLrq8NNqXEeEDxsjqRcBDXesy2Gkrg== X-Received: by 2002:a2e:4a19:: with SMTP id x25-v6mr7678933lja.19.1548416674512; Fri, 25 Jan 2019 03:44:34 -0800 (PST) Received: from mimer.lan (h-29-16.A159.priv.bahnhof.se. [79.136.29.16]) by smtp.gmail.com with ESMTPSA id l3-v6sm1490962ljg.21.2019.01.25.03.44.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Jan 2019 03:44:34 -0800 (PST) From: Jonas Bonn To: linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: [PATCH 2/2] spi-atmel: support inter-word delay Date: Fri, 25 Jan 2019 12:44:29 +0100 Message-Id: <20190125114429.20066-3-jonas@norrbonn.se> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190125114429.20066-1-jonas@norrbonn.se> References: <20190125114429.20066-1-jonas@norrbonn.se> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190125_034436_876469_FB582336 X-CRM114-Status: GOOD ( 11.83 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexandre Belloni , Jonas Bonn , Ludovic Desroches , 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 If the SPI slave requires an inter-word delay, configure the DLYBCT register accordingly. Tested on a SAMA5D2 board (derived from SAMA5D2-Xplained reference board). Signed-off-by: Jonas Bonn CC: Nicolas Ferre CC: Mark Brown CC: Alexandre Belloni CC: Ludovic Desroches CC: linux-spi@vger.kernel.org CC: linux-arm-kernel@lists.infradead.org --- drivers/spi/spi-atmel.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 74fddcd3282b..88ff3fef56e9 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -1209,13 +1209,14 @@ static int atmel_spi_setup(struct spi_device *spi) csr |= SPI_BIT(CSAAT); /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs. - * - * DLYBCT would add delays between words, slowing down transfers. - * It could potentially be useful to cope with DMA bottlenecks, but - * in those cases it's probably best to just use a lower bitrate. */ csr |= SPI_BF(DLYBS, 0); - csr |= SPI_BF(DLYBCT, 0); + + /* DLYBCT adds delays between words. This is useful for slow devices + * that need a bit of time to setup the next transfer. + */ + csr |= SPI_BF(DLYBCT, + clamp_t(u8, (as->spi_clk/1000000*spi->word_delay)>>5, 1, 255)); /* chipselect must have been muxed as GPIO (e.g. in board setup) */ npcs_pin = (unsigned long)spi->controller_data; -- 2.19.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel