[PATCH] spi: omap2-mcspi: Configure hardware when slave driver changes mode

* [PATCH] spi: omap2-mcspi: Configure hardware when slave driver changes mode
@ 2014-07-02  3:28 Mark A. Greer
  2014-07-03 18:49   ` Mark Brown
  0 siblings, 1 reply; 3+ messages in thread
From: Mark A. Greer @ 2014-07-02  3:28 UTC (permalink / raw)
  To: Mark Brown
  Cc: linux-spi-u79uwXL29TY76Z2rM5mHXA,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
	linux-omap-u79uwXL29TY76Z2rM5mHXA, Mark A. Greer,
	Stefan Sørensen

Commit id 2bd16e3e23d9df41592c6b257c59b6860a9cc3ea
(spi: omap2-mcspi: Do not configure the controller
on each transfer unless needed) does its job too
well so omap2_mcspi_setup_transfer() isn't called
even when an SPI slave driver changes 'spi->mode'.
The result is that the mode requested by the SPI
slave driver never takes effect.

Fix this by adding the 'mode' member to the
omap2_mcspi_cs structure which holds the mode
value that the hardware is configured for.
When the SPI slave driver changes 'spi->mode'
it will be different than the value of this new
member and the SPI master driver will know that
the hardware must be reconfigured (by calling
omap2_mcspi_setup_transfer()).

CC: Stefan Sørensen <stefan.sorensen-usnHOLptxrsHrNJx0XZkJA@public.gmane.org>
Signed-off-by: Mark A. Greer <mgreer-luAo+O/VEmrlveNOaEYElw@public.gmane.org>
---
 drivers/spi/spi-omap2-mcspi.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 4dc77df..68441fa 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -149,6 +149,7 @@ struct omap2_mcspi_cs {
 	void __iomem		*base;
 	unsigned long		phys;
 	int			word_len;
+	u16			mode;
 	struct list_head	node;
 	/* Context save and restore shadow register */
 	u32			chconf0, chctrl0;
@@ -926,6 +927,8 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
 
 	mcspi_write_chconf0(spi, l);
 
+	cs->mode = spi->mode;
+
 	dev_dbg(&spi->dev, "setup: speed %d, sample %s edge, clk %s\n",
 			speed_hz,
 			(spi->mode & SPI_CPHA) ? "trailing" : "leading",
@@ -998,6 +1001,7 @@ static int omap2_mcspi_setup(struct spi_device *spi)
 			return -ENOMEM;
 		cs->base = mcspi->base + spi->chip_select * 0x14;
 		cs->phys = mcspi->phys + spi->chip_select * 0x14;
+		cs->mode = 0;
 		cs->chconf0 = 0;
 		cs->chctrl0 = 0;
 		spi->controller_state = cs;
@@ -1079,6 +1083,16 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 	cs = spi->controller_state;
 	cd = spi->controller_data;
 
+	/*
+	 * The slave driver could have changed spi->mode in which case
+	 * it will be different from cs->mode (the current hardware setup).
+	 * If so, set par_override (even though its not a parity issue) so
+	 * omap2_mcspi_setup_transfer will be called to configure the hardware
+	 * with the correct mode on the first iteration of the loop below.
+	 */
+	if (spi->mode != cs->mode)
+		par_override = 1;
+
 	omap2_mcspi_set_enable(spi, 0);
 	list_for_each_entry(t, &m->transfers, transfer_list) {
 		if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
-- 
1.9.0

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