mtd: spi-nor: improve wait-till-ready timeout loop

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=a95ce92e4b289228c51114dd19f714388093d52b
Commit:     a95ce92e4b289228c51114dd19f714388093d52b
Parent:     05a221bb1f49e6eebc9a3858cb45506f403b3ab6
Author:     Brian Norris <computersforpeace at gmail.com>
AuthorDate: Wed Nov 5 02:32:03 2014 -0800
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Tue Nov 25 22:51:23 2014 -0800

    mtd: spi-nor: improve wait-till-ready timeout loop
    
    There are a few small issues with the timeout loop in
    spi_nor_wait_till_ready():
    
     * The first operation should not be a reschedule; we should check the
       status register at least once to see if we're complete!
    
     * We should check the status register one last time after declaring the
       deadline has passed, to prevent a premature timeout error (this is
       theoretically possible if we sleep for a long time after the previous
       status register check).
    
     * Add an error message, so it's obvious if we ever hit a timeout.
    
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
    Acked-by: Huang Shijie <shijie.huang at intel.com>
    Reviewed-by: Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
---
 drivers/mtd/spi-nor/spi-nor.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index eafaeeb..2bda622 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -202,19 +202,24 @@ static int spi_nor_ready(struct spi_nor *nor)
 static int spi_nor_wait_till_ready(struct spi_nor *nor)
 {
 	unsigned long deadline;
-	int ret;
+	int timeout = 0, ret;
 
 	deadline = jiffies + MAX_READY_WAIT_JIFFIES;
 
-	do {
-		cond_resched();
+	while (!timeout) {
+		if (time_after_eq(jiffies, deadline))
+			timeout = 1;
 
 		ret = spi_nor_ready(nor);
 		if (ret < 0)
 			return ret;
 		if (ret)
 			return 0;
-	} while (!time_after_eq(jiffies, deadline));
+
+		cond_resched();
+	}
+
+	dev_err(nor->dev, "flash operation timed out\n");
 
 	return -ETIMEDOUT;
 }