From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933532AbbJHOpG (ORCPT ); Thu, 8 Oct 2015 10:45:06 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:38505 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933388AbbJHOpE (ORCPT ); Thu, 8 Oct 2015 10:45:04 -0400 From: Neil Armstrong Subject: [RFC PATCH] spi: omap2-mcspi: disable other channels CHCONF_FORCE in prepare_message To: Mark Brown , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Michael Welling , Fionn Cleary , Wolfram Sang , Jarkko Nikula , Sebastian Reichel Organization: Baylibre Message-ID: <5616816C.9020904@baylibre.com> Date: Thu, 8 Oct 2015 16:45:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since the "Switch driver to use transfer_one" change, the cs_change behavior has changed and a channel chip select can still be asserted when changing channel from a previous last transfer in s message having the cs_change attribute. Since there is no sense having multiple chip select being asserted at the same time, disable all the remaining forces chip selects in a the prepare_message called right before a spi_transfer_one_message call. This is also a bug fix found in the McSPI into a DM8168 SoC, hanging all the other channels transfers when a CHCONF_FORCE is present. Signed-off-by: Neil Armstrong --- drivers/spi/spi-omap2-mcspi.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) This is a patch RFC following the bug report : 'McSPI hangs with cs_change after "Switch driver to use transfer_one" change' http://permalink.gmane.org/gmane.linux.kernel/2056841 diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index 3d09e0b..db1b655 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -1217,6 +1217,33 @@ out: return status; } +static int omap2_mcspi_prepare_message(struct spi_master *master, + struct spi_message *msg) +{ + struct omap2_mcspi *mcspi = spi_master_get_devdata(master); + struct omap2_mcspi_regs *ctx = &mcspi->ctx; + struct omap2_mcspi_cs *cs; + + /* Only a single channel can have the FORCE bit enabled + * in its chconf0 register. + * Scan all channels and disable them. + * A FORCE can remain from a last transfer having cs_change enabled + */ + + /* Ignore message */ + (void)msg; + + list_for_each_entry(cs, &ctx->cs, node) { + if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE)) { + cs->chconf0 &= ~OMAP2_MCSPI_CHCONF_FORCE; + writel_relaxed(cs->chconf0, + cs->base + OMAP2_MCSPI_CHCONF0); + } + } + + return 0; +} + static int omap2_mcspi_transfer_one(struct spi_master *master, struct spi_device *spi, struct spi_transfer *t) { @@ -1344,6 +1371,7 @@ static int omap2_mcspi_probe(struct platform_device *pdev) master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32); master->setup = omap2_mcspi_setup; master->auto_runtime_pm = true; + master->prepare_message = omap2_mcspi_prepare_message; master->transfer_one = omap2_mcspi_transfer_one; master->set_cs = omap2_mcspi_set_cs; master->cleanup = omap2_mcspi_cleanup; -- 1.9.1