From patchwork Mon Apr 13 10:59:30 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Grzeschik X-Patchwork-Id: 6207271 Return-Path: X-Original-To: patchwork-linux-spi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id DF172BF4A6 for ; Mon, 13 Apr 2015 11:00:07 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1DFD520138 for ; Mon, 13 Apr 2015 11:00:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 27AD5200CF for ; Mon, 13 Apr 2015 11:00:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932169AbbDMLAF (ORCPT ); Mon, 13 Apr 2015 07:00:05 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:35886 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753625AbbDMLAE (ORCPT ); Mon, 13 Apr 2015 07:00:04 -0400 Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1Yhc5v-0003Hb-KK; Mon, 13 Apr 2015 12:59:59 +0200 Received: from mgr by dude.hi.pengutronix.de with local (Exim 4.84) (envelope-from ) id 1Yhc5v-0004Vv-Ia; Mon, 13 Apr 2015 12:59:59 +0200 From: Michael Grzeschik To: broonie@kernel.org Cc: kernel@pengutronix.de, linux-arm-kernel@lists.infradead.org, linux-spi@vger.kernel.org Subject: [PATCH v3] spi: bitbang: only toggle bitchanges Date: Mon, 13 Apr 2015 12:59:30 +0200 Message-Id: <1428922770-16955-1-git-send-email-m.grzeschik@pengutronix.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <20150331202306.GX2869@sirena.org.uk> References: <20150331202306.GX2869@sirena.org.uk> X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: mgr@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-spi@vger.kernel.org Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The current implementation of bitbang_txrx_be_cpha0 and bitbang_txrx_be_cpha1 always call setmosi. That runs into several unnecessary calls into the gpiolib when the level of the GPIO actually has not to be changed. This patch changes the routines to remember the last GPIO level and only calls setmosi if an change has to be made. This way it improves the transfer throughput. Signed-off-by: Michael Grzeschik --- v2: - added missing braces v3: - fixed initial value of oldbit - added !! to condition for bool comparison drivers/spi/spi-bitbang-txrx.h | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-bitbang-txrx.h b/drivers/spi/spi-bitbang-txrx.h index c616e41..58606bf 100644 --- a/drivers/spi/spi-bitbang-txrx.h +++ b/drivers/spi/spi-bitbang-txrx.h @@ -49,12 +49,17 @@ bitbang_txrx_be_cpha0(struct spi_device *spi, { /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */ + bool oldbit = !(word & (1 << 31)); /* clock starts at inactive polarity */ for (word <<= (32 - bits); likely(bits); bits--) { /* setup MSB (to slave) on trailing edge */ - if ((flags & SPI_MASTER_NO_TX) == 0) - setmosi(spi, word & (1 << 31)); + if ((flags & SPI_MASTER_NO_TX) == 0) { + if (!!(word & (1 << 31)) != oldbit) { + setmosi(spi, word & (1 << 31)); + oldbit = word & (1 << 31); + } + } spidelay(nsecs); /* T(setup) */ setsck(spi, !cpol); @@ -76,13 +81,18 @@ bitbang_txrx_be_cpha1(struct spi_device *spi, { /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */ + bool oldbit = !(word & (1 << 31)); /* clock starts at inactive polarity */ for (word <<= (32 - bits); likely(bits); bits--) { /* setup MSB (to slave) on leading edge */ setsck(spi, !cpol); - if ((flags & SPI_MASTER_NO_TX) == 0) - setmosi(spi, word & (1 << 31)); + if ((flags & SPI_MASTER_NO_TX) == 0) { + if (!!(word & (1 << 31)) != oldbit) { + setmosi(spi, word & (1 << 31)); + oldbit = word & (1 << 31); + } + } spidelay(nsecs); /* T(setup) */ setsck(spi, cpol);