spi: limit reaches -1, tested 0

With a postfix decrement limit will reach -1 rather than 0, so the warning
will not be issued.

Also, add a cpu_relax() into the busy-wait loop.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Mariusz Ceier <mceier@gmail.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c
index 0480d8bb19d3..014af69fc1bb 100644
--- a/drivers/spi/spi_imx.c
+++ b/drivers/spi/spi_imx.c
@@ -779,7 +779,8 @@ static irqreturn_t interrupt_transfer(struct driver_data *drv_data)
 
                         /* Read trailing bytes */
                         limit = loops_per_jiffy << 1;
-                        while ((read(drv_data) == 0) && limit--);
+                        while ((read(drv_data) == 0) && --limit)
+                                cpu_relax();
 
                         if (limit == 0)
                                 dev_err(&drv_data->pdev->dev,