linux-kernel - Re: [PATCH] applesmc: Bump max wait and rearrange udelay

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Message-ID: <alpine.DEB.2.02.1209171416560.3412@ubuntu>
Date:	Mon, 17 Sep 2012 14:22:28 -0400 (EDT)
From:	Parag Warudkar <parag.lkml@...il.com>
To:	Henrik Rydberg <rydberg@...omail.se>
cc:	Parag Warudkar <parag.lkml@...il.com>,
	Guenter Roeck <linux@...ck-us.net>, lm-sensors@...sensors.org,
	linux-kernel@...r.kernel.org, khali@...ux-fr.org
Subject: Re: [PATCH] applesmc: Bump max wait and rearrange udelay



On Mon, 17 Sep 2012, Henrik Rydberg wrote:

> The MBP10,1 experiences a lot of write errors with this patch.

I just noticed a single write failure - are you seeing something similar?

[ 1660.362997] applesmc: send_byte(0x00, 0x0300) fail: 0x00
[ 1660.363002] applesmc: LKSB: write data fail

Since the write fails are confirmed, I've locally dropped the send_byte 
changes and just kept the wait_read ones that haven't caused me any 
trouble yet.

Signed-off-by: Parag Warudkar <parag.lkml@...il.com>

diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index 2827088..2ba298a 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -169,14 +169,14 @@ static int wait_read(void)
 {
 	u8 status;
 	int us;
-	for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
-		udelay(us);
+	for (us = APPLESMC_MIN_WAIT; us <= APPLESMC_MAX_WAIT; us <<= 1) {
 		status = inb(APPLESMC_CMD_PORT);
 		/* read: wait for smc to settle */
 		if (status & 0x01)
 			return 0;
+		if (us < APPLESMC_MAX_WAIT)
+			usleep_range(us, us << 1);
 	}
-
 	pr_warn("wait_read() fail: 0x%02x\n", status);
 	return -EIO;
 }
--
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