Hi Paul,
On 4/4/2011 12:17 PM, Paul Walmsley wrote:
On Fri, 1 Apr 2011, Rajendra Nayak wrote:
On 4/1/2011 8:21 PM, Rajendra Nayak wrote:
In omap_hwmod.c:_enable(), what do you think about:
1. saving the current idle mode of the clockdomain,
2. forcing the clockdomain to software-supervised wakeup.
3. enabling clocks and waiting for the module as we currently do, then
4. switching the clockdomain's idle mode back to its original state?
Seems like that would be a reasonable approach for the short term, at
least for drivers that have been converted to PM runtime.
Ok, I'll try and get some RFC patches in these lines soon.
I tried some of what you were suggesting here and it seems to
work well, like you said, for the drivers which are converted
to PM runtime.
Now the issue seems to be, how do we handle the ones which
are *still* using clock framework to enable main clocks and
are yet to be converted to PM runtime.
One such, MMC, is showing me issues on OMAP4 even at boot
and causes a crash.
Its a different thing that some of these drivers which use
direct clock calls are working by fluke on OMAP4 since the
clock framework does not even wait for the modules to become
accessible after the clock enable.
I know the right way seems to be to get all these drivers
converted to PM runtime, but that might take sometime.
One way I am able to get this working (atleast MMC)
is by preventing the clock domain belonging to MMC module
from being programmed into HW_SUP mode.
What programs the OMAP4 clockdomains into hwsup mode in the first place?
This is not yet in mainline, but being done by Santosh's series which
adds OMAP4 low power support in idle and suspend.
http://marc.info/?l=linux-omap&m=130130417927632&w=2
There's no clkdms_setup() as there is in mach-omap2/pm34xx.c. I guess
maybe this code in mach-omap2/pm.c might do it as a side effect:
switch (sleep_switch) {
case FORCEWAKEUP_SWITCH:
if (pwrdm->pwrdm_clkdms[0]->flags& CLKDM_CAN_ENABLE_AUTO)
clkdm_allow_idle(pwrdm->pwrdm_clkdms[0]);
else
clkdm_sleep(pwrdm->pwrdm_clkdms[0]);
break;
If I'm reading this code correctly, it will always force clockdomains that
support hwsup mode into hwsup mode, even if they've been previously
programmed to swsup mode. That's not right. This function should leave
the clockdomain's autoidle setting where it was when the function was
entered. So this needs to be fixed also.
You are right, the code is buggy, I just posted a short series which
should fix this.
http://marc.info/?l=linux-omap&m=130200752115352&w=2
Acceptable hack in the interim while we wait for the MMC driver to be
using PM runtime?
Ideally this should be overridden in the code, not the data, since this
hack is needed due to a software problem, not a hardware problem. The
clockdomains data should just be a statement of what the hardware
supports.
But given the above bug and the lack of some clkdms_setup() function for
OMAP4, I guess the clockdomains data is the least bad choice for right
now, provided that the patch also:
With Santosh's series which adds the clkdms_setup and my series
to fix the above bug, I should be able to handle this in the code,
rather than hack the clockdomains data.
I will post some patches for that as well.
regards
Rajendra
1. puts a big comment in that data warning about the problem and
explaining why
2. puts a pr_warn() in mach-omap2/pm44xx.c:omap4_pm_init() saying:
"WARNING: OMAP4 power savings limited since MMC driver not converted to
PM runtime"
- Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
