Patchwork [RESEND] mtd: docg4: fix status polling loop

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Submitter Mike Dunn
Date Aug. 5, 2013, 5:55 p.m.
Message ID <1375725353-2217-1-git-send-email-mikedunn@newsguy.com>
Download mbox | patch
Permalink /patch/264727/
State New
Headers show

Comments

Mike Dunn - Aug. 5, 2013, 5:55 p.m.
The loop that polls the status register waiting for an operation to complete
foolishly bases the timeout simply on the number of loop iterations that have
ocurred.  When I increased the processor clock speed, timeouts started to appear
for long block erasure operations.  This patch measures the timeout using
jiffies.

Signed-off-by: Mike Dunn <mikedunn@newsguy.co>
---

This is a rework of an earlier patch, based on Artem's recommendation to use
jiffies, not udelay() (thanks Artem).  I didn't mark it 'v2' because the rework
makes the original name of the patch inaccurate, so now it has a different name.

This was originally sent a couple months ago... was probably a bad time.

 drivers/mtd/nand/docg4.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

Patch

diff --git a/drivers/mtd/nand/docg4.c b/drivers/mtd/nand/docg4.c
index fa25e7a..6c3be21 100644
--- a/drivers/mtd/nand/docg4.c
+++ b/drivers/mtd/nand/docg4.c
@@ -44,6 +44,7 @@ 
 #include <linux/mtd/nand.h>
 #include <linux/bch.h>
 #include <linux/bitrev.h>
+#include <linux/jiffies.h>
 
 /*
  * In "reliable mode" consecutive 2k pages are used in parallel (in some
@@ -269,7 +270,7 @@  static int poll_status(struct docg4_priv *doc)
 	 */
 
 	uint16_t flash_status;
-	unsigned int timeo;
+	unsigned long timeo;
 	void __iomem *docptr = doc->virtadr;
 
 	dev_dbg(doc->dev, "%s...\n", __func__);
@@ -277,22 +278,18 @@  static int poll_status(struct docg4_priv *doc)
 	/* hardware quirk requires reading twice initially */
 	flash_status = readw(docptr + DOC_FLASHCONTROL);
 
-	timeo = 1000;
+	timeo = jiffies + msecs_to_jiffies(200); /* generous timeout */
 	do {
 		cpu_relax();
 		flash_status = readb(docptr + DOC_FLASHCONTROL);
-	} while (!(flash_status & DOC_CTRL_FLASHREADY) && --timeo);
+	} while (!(flash_status & DOC_CTRL_FLASHREADY) &&
+		 time_before(jiffies, timeo));
 
-
-	if (!timeo) {
+	if (unlikely(!(flash_status & DOC_CTRL_FLASHREADY))) {
 		dev_err(doc->dev, "%s: timed out!\n", __func__);
 		return NAND_STATUS_FAIL;
 	}
 
-	if (unlikely(timeo < 50))
-		dev_warn(doc->dev, "%s: nearly timed out; %d remaining\n",
-			 __func__, timeo);
-
 	return 0;
 }