Input: i8042 - fix AUX port detection with some chips

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.

Signed-off-by: Roland Scheidegger <sroland@tungstengraphics.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 7c17377a65b96b99cb342158ad449d60c7f8619d..3888dc307e0ce09d47aebc89eeb983df02be5f40 100644 (file)
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -526,6 +526,33 @@ static irqreturn_t __devinit i8042_aux_test_irq(int irq, void *dev_id)
        return IRQ_HANDLED;
 }
 
+/*
+ * i8042_toggle_aux - enables or disables AUX port on i8042 via command and
+ * verifies success by readinng CTR. Used when testing for presence of AUX
+ * port.
+ */
+static int __devinit i8042_toggle_aux(int on)
+{
+       unsigned char param;
+       int i;
+
+       if (i8042_command(&param,
+                       on ? I8042_CMD_AUX_ENABLE : I8042_CMD_AUX_DISABLE))
+               return -1;
+
+       /* some chips need some time to set the I8042_CTR_AUXDIS bit */
+       for (i = 0; i < 100; i++) {
+               udelay(50);
+
+               if (i8042_command(&param, I8042_CMD_CTL_RCTR))
+                       return -1;
+
+               if (!(param & I8042_CTR_AUXDIS) == on)
+                       return 0;
+       }
+
+       return -1;
+}
 
 /*
  * i8042_check_aux() applies as much paranoia as it can at detecting
@@ -580,16 +607,12 @@ static int __devinit i8042_check_aux(void)
  * Bit assignment test - filters out PS/2 i8042's in AT mode
  */
 
-       if (i8042_command(&param, I8042_CMD_AUX_DISABLE))
-               return -1;
-       if (i8042_command(&param, I8042_CMD_CTL_RCTR) || (~param & I8042_CTR_AUXDIS)) {
+       if (i8042_toggle_aux(0)) {
                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))
+       if (i8042_toggle_aux(1))
                return -1;
 
 /*