linux-imx

ARM: OMAP3: Fix I/O chain clock line assertion timed out error

We are getting "PRM: I/O chain clock line assertion timed out" errors
on early omaps for device tree based booting. This is because we are
unconditionally calling reconfigure_io_chain while legacy booting
has omap3_has_io_chain_ctrl() checks in place in omap_hwmod.c.

For device tree based booting, we are calling reconfigure_io_chain
unconditionally from pinctrl framework. So we need to add a check for
omap3_has_io_chain_ctrl() to avoid the errors for trying to access
a register that does not exist.

For es3.0, the documentation in "4.11.2 Device Off-Mode Configuration"
just mentions PM_WKEN_WKUP[8] bit. For es3.1, there's a new chapter in
documentation for "4.11.2.2 I/O Wake-Up Mechanism" that describes the
PM_WKEN_WKUP[16] ST_IO_CHAIN bit. So PM_WKEN_WKUP[16] bit did not get
added until in es3.1 probaly to fix issues with flakey wake-up events.

We are doing proper checks for ST_IO_CHAIN already in id.c and with
omap3_has_io_chain_ctrl(). For more information, see also commit
b02b917211d5 ("ARM: OMAP3: PM: fix I/O wakeup and I/O chain clock
control detection").

Let's fix the issue by selecting the right function during init for
reconfigure_io_chain depending on the omap revision. For es3.0 and
earlier we need to just toggle EN_IO. By doing this, we can move the
check for omap3_has_io_chain_ctrl() from omap_hwmod.c to the init code
in prm_3xxx.c. And then we can unconditionally call reconfigure_io_chain.

Thanks to Paul Walmsley and Nishanth Menon for help with debugging the
issue.

Fixes: 30a69ef785e8 ("ARM: OMAP: Move DT wake-up event handling over to use pinctrl-single-omap")
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>