From patchwork Sat Jan 26 16:32:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonas Bonn X-Patchwork-Id: 10782509 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D4CFF139A for ; Sat, 26 Jan 2019 16:32:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BB25E2E387 for ; Sat, 26 Jan 2019 16:32:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AEF0F2E38A; Sat, 26 Jan 2019 16:32:27 +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=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,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 233042E387 for ; Sat, 26 Jan 2019 16:32:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726145AbfAZQc0 (ORCPT ); Sat, 26 Jan 2019 11:32:26 -0500 Received: from mail-lf1-f66.google.com ([209.85.167.66]:44050 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726038AbfAZQc0 (ORCPT ); Sat, 26 Jan 2019 11:32:26 -0500 Received: by mail-lf1-f66.google.com with SMTP id z13so9006572lfe.11 for ; Sat, 26 Jan 2019 08:32:25 -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:mime-version :content-transfer-encoding; bh=kS5H/aXW8GuV+ml679sxzZ/9wuuF0lVRxh23dupYwdQ=; b=HkUUTddOVU9DoiJ6tr9HDAPjUavOUN1er30Nt0VEC0kDHOOUnOJxkUo/R9laKhoZxj 7FWS+MIk0ZCTrK3Tr3lI121wEIc/JvCDV4nr6iJTEwdnmSpTKSnrvHkPg6bi/rWI37kK VFPFnjls23m40ElKlrniGukTJLoIaT1pi+ayHjNpobC+Dt16KcT4T5aGGaWqgx9dfaiG RLDjcar2I94LJg1zgW2K3Dz8VO0xmaxd0Am+YBZ8F33ZRguZgzU7eYLJ9XBWFowCmEbc UsFAD00yLrO4P2sLNVKgVR6zBHrKbJ9/HrnuFSUGHaxEfZHoMRZdzTxjsLgdZzx8TOBr jNlw== 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:mime-version :content-transfer-encoding; bh=kS5H/aXW8GuV+ml679sxzZ/9wuuF0lVRxh23dupYwdQ=; b=cDI3slMSsUJ+CZTPYNU/kKAOjGUIA6kLLS1zg01MfC2FTmQvZQG1azGvO9aV3x47L3 4i+EABcQJvGmQLDbb3TxT231UjgL3uawA/FFpDFB9bc274fOHPXaLD9/yWK25i5kKbW6 88OP7RrevvAt2Zk5X78Gz3iw3dna+gZ7rXLhHwEl1P45pNkHoR7gGzTb7yfS2jfEVp/r XKeNNqa5AexVTGxWa0LNfktQwyUf/cs1rHFnW7q1ccwMVCSNBoQmtLDrXcodaZqFdY0T F5Zdmuo+dNscIOXNAoMIS4fBjXN4AjblmczyoTXDpAi6oSmkh9qSsFC5+34R0NV/Am1D MeWg== X-Gm-Message-State: AJcUukeCJS5hEgyJw5tbo1V5kSTuXKYQlbRr2SzXpHXysE0z8JEZJgCe 9/HpUpRfaMK2eEjpaR8tQ7HA2kx1pwU= X-Google-Smtp-Source: ALg8bN7auManVNcXvNC0adk6cLwS53omYHeXvQ3IKRI+5FPlGLjNBN/V6magOWSC8fouvtvyYSImCA== X-Received: by 2002:ac2:5599:: with SMTP id v25mr12652916lfg.169.1548520344420; Sat, 26 Jan 2019 08:32:24 -0800 (PST) Received: from mimer.lan (h-29-16.A159.priv.bahnhof.se. [79.136.29.16]) by smtp.gmail.com with ESMTPSA id e94sm2170532lfi.23.2019.01.26.08.32.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 26 Jan 2019 08:32:23 -0800 (PST) From: Jonas Bonn To: linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Cc: Jonas Bonn Subject: [PATCH v3 0/2] spi: support inter-word delays Date: Sat, 26 Jan 2019 17:32:18 +0100 Message-Id: <20190126163220.26421-1-jonas@norrbonn.se> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 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 Changed in v3: * Drop setting of inter-word delay via device tree Changed in v2: * Fix atmel-spi driver to not unconditionally set minimal delay if no delay is required (erroneous clamping) This short series adds support for SPI inter-word delays and configures the spi-atmel driver to honour the setting. Some SPI slaves are so slow that they are unable to keep up even at the SPI controller's lowest available clock frequency. I have such a configuration where an AVR-based SPI slave is unable to feed the SPI bus fast enough even the SPI master runs at the lowest possible clock speed. Jonas Bonn (2): spi: support inter-word delay requirement for devices spi-atmel: support inter-word delay drivers/spi/spi-atmel.c | 18 +++++++++++++----- include/linux/spi/spi.h | 3 +++ 2 files changed, 16 insertions(+), 5 deletions(-)