The patch titled hwmon: applesmc: lighter wait mechanism, drastic improvement has been added to the -mm tree. Its filename is hwmon-applesmc-lighter-wait-mechanism-drastic-improvement.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: hwmon: applesmc: lighter wait mechanism, drastic improvement From: Henrik Rydberg <rydberg@xxxxxxxxxxx> The read fail ratio is sensitive to the delay between the first byte written and the first byte read; apparently the sensors cannot be rushed. Increasing the minimum wait time, without changing the total wait time, improves the fail ratio from a 8% chance that any of the sensors fails in one read, down to 0.4%, on a Macbook Air. On a Macbook Pro 3,1, the effect is even more apparent. By reducing the number of status polls, the ratio is further improved to below 0.1%. Finally, increasing the total wait time brings the fail ratio down to virtually zero. Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx> Tested-by: Bob McElrath <bob@xxxxxxxxxxxx> Cc: Nicolas Boichat <nicolas@xxxxxxxxxx> Cc: "Mark M. Hoffman" <mhoffman@xxxxxxxxxxxxx> Cc: Jean Delvare <khali@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/hwmon/applesmc.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff -puN drivers/hwmon/applesmc.c~hwmon-applesmc-lighter-wait-mechanism-drastic-improvement drivers/hwmon/applesmc.c --- a/drivers/hwmon/applesmc.c~hwmon-applesmc-lighter-wait-mechanism-drastic-improvement +++ a/drivers/hwmon/applesmc.c @@ -49,6 +49,9 @@ #define APPLESMC_MAX_DATA_LENGTH 32 +#define APPLESMC_MIN_WAIT 0x0040 +#define APPLESMC_MAX_WAIT 0x8000 + #define APPLESMC_STATUS_MASK 0x0f #define APPLESMC_READ_CMD 0x10 #define APPLESMC_WRITE_CMD 0x11 @@ -172,25 +175,25 @@ static unsigned int key_at_index; static struct workqueue_struct *applesmc_led_wq; /* - * __wait_status - Wait up to 10ms for the status port to get a certain value + * __wait_status - Wait up to 32ms for the status port to get a certain value * (masked with 0x0f), returning zero if the value is obtained. Callers must * hold applesmc_lock. */ static int __wait_status(u8 val) { - unsigned int i; + int us; val = val & APPLESMC_STATUS_MASK; - for (i = 0; i < 1000; i++) { + for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { + udelay(us); if ((inb(APPLESMC_CMD_PORT) & APPLESMC_STATUS_MASK) == val) { if (debug) printk(KERN_DEBUG - "Waited %d us for status %x\n", - i*10, val); + "Waited %d us for status %x\n", + 2 * us - APPLESMC_MIN_WAIT, val); return 0; } - udelay(10); } printk(KERN_WARNING "applesmc: wait status failed: %x != %x\n", @@ -206,13 +209,12 @@ static int __wait_status(u8 val) */ static int send_command(u8 cmd) { - int i; - for (i = 0; i < 1000; i++) { + int us; + for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { outb(cmd, APPLESMC_CMD_PORT); - udelay(5); + udelay(us); if ((inb(APPLESMC_CMD_PORT) & APPLESMC_STATUS_MASK) == 0x0c) return 0; - udelay(5); } printk(KERN_WARNING "applesmc: command failed: %x -> %x\n", cmd, inb(APPLESMC_CMD_PORT)); _ Patches currently in -mm which might be from rydberg@xxxxxxxxxxx are input-mousedev-distinguish-a-moving-finger-from-a-tapping-finger.patch hwmon-applesmc-specified-number-of-bytes-to-read-should-match-actual.patch hwmon-applesmc-fix-the-wait-status-failed-c-=-8-problem.patch hwmon-applesmc-prolong-status-wait.patch hwmon-applesmc-allow-for-variable-alv0-and-alv1-package-length.patch hwmon-applesmc-add-support-for-macbook-air.patch drivers-hwmon-applesmcc-remove-unneeded-casts.patch hwmon-applesmc-add-support-for-macbook-pro-4.patch hwmon-applesmc-add-support-for-macbook-pro-3.patch hwmon-applesmc-lighter-wait-mechanism-drastic-improvement.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html