[Patch v2 1/3] spi/dw_spi: Fix too short timeout in spi polling loop

[Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

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...

Acked-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Signed-off-by: Arjan van de Ven <arjan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Signed-off-by: Alan Cox <alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/spi/dw_spi.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 0838c79..25238a8 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);
 }
-- 
1.7.0.4


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