Without the fix below, reading back the state of the impulse switch
(GPIO24) on my ALIX always returned '0' (e.g. switch is pressed). Now it
returns '1' if depressed, and '0' only while pressing it, as expected.
As AMD5536_GPIO_READ_BACK was already #defined but so far unused, I
assume it was just a small oversight which crept through testing while
reading back the LEDs' state only. See p. 480ff in the CS4436 Companion
Data Book for a detailed description of the registers in question.
Note: This fix changes the values returned while reading the LEDs' state
(GPIO6, 25 and 27). Before, they alway reflected the last state written
(LED on or off). Now, they always return '0', unless you set 'in' flag,
upon which it returns always '1'.
The LEDs' current state can't be read back anymore this manner because
these GPIOs do not support the 'inout' flag.
Rolf
--- sys/arch/i386/pci/glxpcib.c.orig Sat Nov 24 09:21:00 2007
+++ sys/arch/i386/pci/glxpcib.c Tue Mar 18 15:55:51 2008
@@ -291,7 +291,7 @@
u_int32_t data;
int reg;
- reg = AMD5536_GPIO_OUT_VAL;
+ reg = AMD5536_GPIO_READ_BACK;
if (pin > 15) {
pin &= 0x0f;
reg += AMD5536_GPIOH_OFFSET;
