spi_mpc83xx: add small delay after asserting chip-select line

This is needed for some underlaying GPIO controllers that may be a bit
slow, or if chip-select signal need some time to stabilize.

For what it's worth, we already have the similar delay for chip-select
de-assertion case.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: David Brownell <david-b@pacbell.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
index 4988230..6e0232e 100644 (file)
--- a/drivers/spi/spi_mpc83xx.c
+++ b/drivers/spi/spi_mpc83xx.c
@@ -383,8 +383,10 @@ static void mpc83xx_spi_work(struct work_struct *work)
                                        break;
                        }
 
-                       if (cs_change)
+                       if (cs_change) {
                                mpc83xx_spi_chipselect(spi, BITBANG_CS_ACTIVE);
+                               ndelay(nsecs);
+                       }
                        cs_change = t->cs_change;
                        if (t->len)
                                status = mpc83xx_spi_bufs(spi, t);