From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752718AbaFMSOB (ORCPT ); Fri, 13 Jun 2014 14:14:01 -0400 Received: from mail-qa0-f73.google.com ([209.85.216.73]:41621 "EHLO mail-qa0-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751134AbaFMSN5 (ORCPT ); Fri, 13 Jun 2014 14:13:57 -0400 From: Doug Anderson To: Samuel Ortiz , Lee Jones , Kukjin Kim Cc: Tomasz Figa , broonie@kernel.org, sjg@chromium.org, olof@lixom.net, javier.martinez@collabora.co.uk, ch.naveen@samsung.com, swarren@wwwdotorg.org, khilman@linaro.org, ajaynumb@gmail.com, rahul.sharma@samsung.com, tushar.b@samsung.com, linux-samsung-soc@vger.kernel.org, Doug Anderson , linux-kernel@vger.kernel.org Subject: [PATCH 1/2] mfd: cros_ec: spi: Fix end of transfer on devices with no spi-msg-delay Date: Fri, 13 Jun 2014 11:13:32 -0700 Message-Id: <1402683213-23120-1-git-send-email-dianders@chromium.org> X-Mailer: git-send-email 2.0.0.526.g5318336 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cros_ec_spi makes the assumption that a 0-length message will put the spi chip select back to normal (non cs_toggle mode). This used to be the case back on kernel-3.8 on the spi-s3c64xx driver but doesn't appear to be true anymore. It seems like it was a pretty questionable assumption to begin with, so let's fix the code to be more robust. We know that a message with a single 0-length segment _will_ put things back in order. Change cros_ec_spi to handle this. This wasn't a problem on the main user of cros_ec_spi upstream (tegra) because it specified 'google,cros-ec-spi-msg-delay'. Signed-off-by: Doug Anderson --- drivers/mfd/cros_ec_spi.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-) diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index 0b8d328..0cbc3db 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -266,18 +266,14 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); } - /* turn off CS */ + /* + * Turn off CS, possibly adding a delay to ensure the rising edge + * doesn't come too soon after the end of the data. + */ spi_message_init(&msg); - - if (ec_spi->end_of_msg_delay) { - /* - * Add delay for last transaction, to ensure the rising edge - * doesn't come too soon after the end of the data. - */ - memset(&trans, 0, sizeof(trans)); - trans.delay_usecs = ec_spi->end_of_msg_delay; - spi_message_add_tail(&trans, &msg); - } + memset(&trans, 0, sizeof(trans)); + trans.delay_usecs = ec_spi->end_of_msg_delay; + spi_message_add_tail(&trans, &msg); final_ret = spi_sync(ec_spi->spi, &msg); ktime_get_ts(&ts); -- 2.0.0.526.g5318336