Hi,
On a custom am335x board I was surprised to see the kernel resetting
gpio pins not mentioned anywhere in the dts.
In this specific case the pin is connected to nCONFIG of a FPGA. The
FPGA is commanded to start configuration from a SPI flash in the
bootloader, so it can happen in parallel with kernel
load/uncompress/startup, but as the kernel resets the gpio during
initialization this doesn't work.
Digging a bit into it, I see the hwmod of the gpio controller is
configured to reset at startup, and it works correctly (E.G. the pin is
left asserted) if I change it to HWMOD_INIT_NO_RESET:
--- a/arch/arm/mach-omap2/omap_hwmod_33xx_data.c
+++ b/arch/arm/mach-omap2/omap_hwmod_33xx_data.c
@@ -992,7 +992,7 @@ static struct omap_hwmod am33xx_gpio1_hwmod = {
.name = "gpio2",
.class = &am33xx_gpio_hwmod_class,
.clkdm_name = "l4ls_clkdm",
- .flags = HWMOD_CONTROL_OPT_CLKS_IN_RESET,
+ .flags = (HWMOD_INIT_NO_IDLE | HWMOD_INIT_NO_RESET),
.mpu_irqs = am33xx_gpio1_irqs,
.main_clk = "l4ls_gclk",
.prcm = {
Now the question is why is this configured like this? I don't have any
experience with omap hwmod, but on other (non-TI) boards I haven't
experienced similar issues. Should E.G. the gpio controllers be changed
to not reset or should it be configurable in the dts?
--
Bye, Peter Korsgaard
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