input: fix aux port detection with some i8042 chips

From: Roland Scheidegger <[email protected]>

The i8042 driver fails detection of the AUX port with some chips, because they apparently do not change the I8042_CTR_AUXDIS bit immediately. This is known to affect at least HP500 / HP510 notebooks, consequently the built-in touchpad will not work. The patch will simply reread the value until it gets the expected value or a retry limit is hit, without touching other workaround code in the same area.

---
There is some discussion about non-working touchpads in HP500 notebooks in ubuntu and a (ugly) workaround for this problem here:
http://ubuntuforums.org/showthread.php?t=344103. I've got a HP510 and even with 2.6.21 the aux port would get disabled. Works with the patch, for the record the i8042 here needs around 6 tries (sometimes a bit more, sometimes less) until it reads the I8042_CTR_AUXDIS bit correctly, both after disabling and enabling the aux port.
(please CC: on any replies)

--- linux-2.6/drivers/input/serio/i8042.c.orig 2007-05-03
16:32:26.000000000 +0200
+++ linux-2.6/drivers/input/serio/i8042.c 2007-05-03 16:56:00.000000000
+0200
@@ -537,6 +537,7 @@ static int __devinit i8042_check_aux(voi
int retval = -1;
int irq_registered = 0;
int aux_loop_broken = 0;
+ int i = 0;
unsigned long flags;
unsigned char param;

@@ -582,14 +583,27 @@ static int __devinit i8042_check_aux(voi

if (i8042_command(&param, I8042_CMD_AUX_DISABLE))
return -1;
- if (i8042_command(&param, I8042_CMD_CTL_RCTR) || (~param &
I8042_CTR_AUXDIS)) {
+ /* some chips need some time to set the I8042_CTR_AUXDIS bit */
+ for (i = 0; i < 100; i++) {
+ if (!i8042_command(&param, I8042_CMD_CTL_RCTR) && (param &
I8042_CTR_AUXDIS))
+ break;
+ udelay(50);
+ }
+ if (i == 100) {
printk(KERN_WARNING "Failed to disable AUX port, but continuing
anyway... Is this a SiS?\n");
printk(KERN_WARNING "If AUX port is really absent please use the
'i8042.noaux' option.\n");
}

if (i8042_command(&param, I8042_CMD_AUX_ENABLE))
return -1;
- if (i8042_command(&param, I8042_CMD_CTL_RCTR) || (param &
I8042_CTR_AUXDIS))
+ for (i = 0; i < 100; i++) {
+ if (i8042_command(&param, I8042_CMD_CTL_RCTR))
+ return -1;
+ if (~param & I8042_CTR_AUXDIS)
+ break;
+ udelay(50);
+ }
+ if (i == 100)
return -1;

/*

Applied with some rearrangements, thank you.

Dmitry