spi/pl022: use cpu_relax in the busy loop

This relaxes the cpu in the polling busy-wait loop.

Reported-by: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
index 18667de..8a2b88a 100644 (file)
--- a/drivers/spi/amba-pl022.c
+++ b/drivers/spi/amba-pl022.c
@@ -1424,6 +1424,7 @@ static void do_polling_transfer(struct pl022 *pl022)
                                message->state = STATE_ERROR;
                                goto out;
                        }
+                       cpu_relax();
                }
 
                /* Update total byte transferred */