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

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()).

Fixes: 2bd16e3e23 (spi: omap2-mcspi: Do not configure the controller on each transfer unless needed)
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 4dc77df38864..68441fa448de 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) {