On 07/09/2013 10:41 PM, Felipe Balbi wrote:
Hi,
On Tue, Jul 09, 2013 at 09:59:28PM +0300, Grygorii Strashko wrote:
Imagine the device is marked as suspended even though it's fully enabled
(it hasn't been suspended by hwmod due to NO_IDLE flag). In that case
your context structure is all zeroes (context has never been saved
before) then when you call pm_runtime_get_sync() on probe() your
->runtime_resume() will get called, which will restore context,
essentially undoing anything which was configured by u-boot.
This could be a problem for drivers which do a save context in ->runtime_suspend()
but from what I see with omap serial, there is no save context done as part of
->runtime_suspend.
right, because context is "saved" in set_termios. probe() will get
called much before set_termios() has a chance to run, right ?
Same problem will trigger in that case.
I still think patch below is necessary
(completely untested, didn't even try to compile, just to illustrate)
diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 7341eff..d8dca68 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -2559,6 +2559,12 @@ static void __init _setup_postsetup(struct omap_hwmod *oh)
(postsetup_state == _HWMOD_STATE_IDLE)) {
oh->_int_flags |= _HWMOD_SKIP_ENABLE;
postsetup_state = _HWMOD_STATE_ENABLED;
+
+ /* tell pm_runtime this device is already active */
+ pm_runtime_set_active(&oh->od->pdev->dev);
+ } else {
+ /* tell pm_runtime this device is trully suspended */
+ pm_runtime_set_suspended(&oh->od->pdev->dev);
}
if (postsetup_state == _HWMOD_STATE_IDLE)
This will not work - _setup_postsetup() is called from core_initcall
level and OMAP devices have not been created at this moment yet
(of_platform_populate() is called from
customize_machine->init_machine->omap_generic_init() at arch_initcall time)
fair enough, but something *like* that needs to be done. If pm_runtime
doesn't know the state of the device by the time pm_runtime_enable() is
called, the wrong assumptions might be made and we will forever have
such problems as our ->runtime_resume() callback being called when it
shouldn't.
More over, I don't recommend to depend on hwmod->od field - it's been
created to support OPPs and it's obsolete now in case of DT use.
that's alright, but still we need something similar.
But in any case, if on DT boot that's not used, than *what* uses
HWMOD_INIT_NO_IDLE during DT boot ?
There's a single place in kernel source which checks if
HWMOD_INIT_NO_IDLE is set, and that's the place which I patched.
We, certainly, need a way to tell pm_runtime if the device is active or
suspended by the time we reach our probe() function. Either we assume
*all* devices are active and we blindly call pm_runtime_set_active() for
all devices, or we assume *all* devices are suspended as we call
pm_runtime_set_suspend() for all devices, or we figure out which ones
are active and which are not and call pm_runtime_set_{active,suspend}()
conditionally.
Seems, This issue need to be handled in driver for DT boot use case,
possibly cmdline need to be parsed in the same way as it's done in
omap_serial_early_init().
so you want *every* single driver to parse their own cmdline ? How big
would the cmdline become ? This makes no sense.
Agree here. Seems there two similar issues:
- this one with omap_serial
- GPIO reset issue http://www.spinics.net/lists/linux-omap/msg84186.html
(similar issue is observed on OMAP4460+TPS6236x)
And I think, that HWMOD_INIT_NO_IDLE and HWMOD_INIT_NO_RESET flags can't
be treated as
SoC (IP) specific parameters any more - they should be board specific.
I think, some kind of board_layout {} DT definition need to be created
to solve these issues (just an idea). For example:
Board DTS file:
board_layout {
ti,hwmods-init-no-reset = "gpio1", "uart3";
ti,hwmods-init-no-idle = "uart3";
}
Then above DT parameters can be used in omap_hwmod_setup_all()->_setup()
and omap_device_build_from_dt().
- omap_hwmod_setup_all()->_setup() will configure hwmod's flags
- omap_device_build_from_dt() will check for HWMOD_INIT_NO_IDLE and
call pm_runtime_set_active() if needed (this is the valid place for that)
NOTE. "ti,hwmods-init-no-reset" and "ti,hwmods-init-no-idle" can't be
defined per device, because HWMOD framework will work
(init/reset/setup/idle) with IP even if corresponding IP is not defined
in DT.
More over, board_layout{} section can be used to define some common for
OMAP2+ boards properties or enable/disable PM features, like:
- Setup clksetup/clkshoutdown time for oscillator
- enable/disable OFF-mode
Regards,
-grygorii
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