I have been getting a steady stream of wait_read timeouts on my 2010 MBP.
After playing around with various values of APPLESMC_MAX_WAIT a value of
0x10000 reduces the wait_read failures to zero under most normal workloads
- with and without AC power plugged in, at idle and and at make -j4 loads.
While there I noticed we don't really need to udelay before first inb() -
so I moved it down to after first and subsequent failures.
Been running this for couple days without any issues.
Signed-off-by: Parag Warudkar <parag.lkml@xxxxxxxxx>
diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index 2827088..46cb458 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -56,7 +56,7 @@
/* wait up to 32 ms for a status change. */
#define APPLESMC_MIN_WAIT 0x0010
#define APPLESMC_RETRY_WAIT 0x0100
-#define APPLESMC_MAX_WAIT 0x8000
+#define APPLESMC_MAX_WAIT 0x10000
#define APPLESMC_READ_CMD 0x10
#define APPLESMC_WRITE_CMD 0x11
@@ -170,11 +170,11 @@ static int wait_read(void)
u8 status;
int us;
for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
- udelay(us);
status = inb(APPLESMC_CMD_PORT);
/* read: wait for smc to settle */
if (status & 0x01)
return 0;
+ udelay(us);
}
pr_warn("wait_read() fail: 0x%02x\n", status);
@@ -192,11 +192,12 @@ static int send_byte(u8 cmd, u16 port)
outb(cmd, port);
for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
- udelay(us);
status = inb(APPLESMC_CMD_PORT);
/* write: wait for smc to settle */
- if (status & 0x02)
+ if (status & 0x02) {
+ udelay(us);
continue;
+ }
/* ready: cmd accepted, return */
if (status & 0x04)
return 0;
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