spi/dw_spi: Fix too short timeout in spi polling loop

The SPI polling loop timeout only works with HZ=100 as the loop was
actually too short.

Also add appropriate cpu_relax() in the busy wait loops...

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 0838c79861e4..25238a82e45e 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -164,20 +164,23 @@ static inline void mrst_spi_debugfs_remove(struct dw_spi *dws)
 
 static void wait_till_not_busy(struct dw_spi *dws)
 {
-        unsigned long end = jiffies + 1 + usecs_to_jiffies(1000);
+        unsigned long end = jiffies + 1 + usecs_to_jiffies(5000);
 
         while (time_before(jiffies, end)) {
                 if (!(dw_readw(dws, sr) & SR_BUSY))
                         return;
+                cpu_relax();
         }
         dev_err(&dws->master->dev,
-                "DW SPI: Status keeps busy for 1000us after a read/write!\n");
+                "DW SPI: Status keeps busy for 5000us after a read/write!\n");
 }
 
 static void flush(struct dw_spi *dws)
 {
-        while (dw_readw(dws, sr) & SR_RF_NOT_EMPT)
+        while (dw_readw(dws, sr) & SR_RF_NOT_EMPT) {
                 dw_readw(dws, dr);
+                cpu_relax();
+        }
 
         wait_till_not_busy(dws);
 }