Messages in this thread | | | Date | Tue, 8 Aug 2023 17:24:03 +0530 | From | Dhruva Gole <> | Subject | Re: [PATCH V6 4/4] firmware: ti_sci: Introduce system suspend resume support |
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Kevin,
Thanks for the suggestion. I have a rough proposal inline, please can you take a look? I will test those changes and respin this series accordingly
On Aug 07, 2023 at 14:57:05 -0700, Kevin Hilman wrote: > Dhruva Gole <d-gole@ti.com> writes: > > > On Aug 03, 2023 at 11:00:11 -0500, Andrew Davis wrote: > >> On 8/3/23 10:55 AM, Dhruva Gole wrote: > >> > On Aug 03, 2023 at 10:26:32 -0500, Andrew Davis wrote: > >> > > On 8/3/23 1:42 AM, Dhruva Gole wrote: > >> > > > Introduce system suspend resume calls that will allow the ti_sci > >> > > > driver to support deep sleep low power mode when the user space issues a > >> > > > suspend to mem. > >> > > > > >> > > > Also, write a ti_sci_prepare_system_suspend call to be used in the driver > >> > > > suspend handler to allow the system to identify the low power mode being > >> > > > entered and if necessary, send TISCI_MSG_PREPARE_SLEEP with information > >> > > > about the mode is being entered and the address for allocated memory for > >> > > > storing the context during Deep Sleep. > >> > > > > >> > > > We're using "pm_suspend_target_state" to map the kernel's target suspend > >> > > > state to SysFW low power mode. Make sure this is available only when > >> > > > CONFIG_SUSPEND is enabled. > >> > > > > >> > > > Co-developed-by: Dave Gerlach <d-gerlach@ti.com> > >> > > > Signed-off-by: Dave Gerlach <d-gerlach@ti.com> > >> > > > Signed-off-by: Vibhore Vardhan <vibhore@ti.com> > >> > > > Signed-off-by: Georgi Vlaev <g-vlaev@ti.com> > >> > > > Signed-off-by: Dhruva Gole <d-gole@ti.com> > >> > > > --- > >> > > > drivers/firmware/ti_sci.c | 63 +++++++++++++++++++++++++++++++++++++++ > >> > > > 1 file changed, 63 insertions(+) > >> > > > > >> > [..snip..] > >> > > > +static int ti_sci_suspend(struct device *dev) > >> > > > +{ > >> > > > + struct ti_sci_info *info = dev_get_drvdata(dev); > >> > > > + int ret; > >> > > > + > >> > > > + ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_ENABLE); > >> > > > >> > > After this the will the IOs be in isolation? Or does the firmware wait > >> > > until power down begins later? > >> > > >> > From what I understand, > >> > IOs will be in isolation immediately > >> > > >> > >> That is what I understand too, so then any device that may need to do some > >> external communication for its suspend will not function, this must be the > >> last driver _suspend() the system calls, how do you enforce that? > > > > I will make use of .suspend_noirq callbacks in that case. Does that > > sound better, or is there anything else I may not be aware of? > > Using _noirq just moves the problem. What if other drivers are also > using _noirq callbacks and run after the SCI driver? You still cannot
True, this thought occurred to me as well which is why I was thinking that moving it to ATF might be a better choice.
> guarantee ordering. > > It seems to me that the IO isolation stuff is a system-wide operation, > and should probably be handled at the platform suspend_ops level > (e.g. suspend_ops->prepare_late()). This would ensure that it runs
I must have missed this approach! Are you suggesting something like what was done for am335?
static const struct platform_suspend_ops am33xx_pm_ops
have a similar code for tisci..?
static const struct platform_suspend_ops tisci_pm_ops = { .prepare_late = tisci_set_io_isolation };
And then while resuming we may want the pinctrl driver to scan for the wk_evt bit[0] before the isolation is disabled, so we want the tisci_resume/ remove isolation to be called later than that.
So I a wondering if the code below makes sense?
static const struct platform_suspend_ops tisci_pm_ops = { .prepare_late = tisci_suspend // also includes set isolation .end = tisci_resume // Disables isolation };
However a minor drawback here maybe that the serial logs on the resume path may not appear when using a serial console for example. However they should be able to easily access using dmesg.
> *after* all the driver hooks (even driver _noirq hooks.) and right > before the full suspend (or s2idle.) > > Now, all that being said, I noticed that in v7, you didn't move this to > _noirq, but instead suggested that this be handled by TF-A. I suppose > that's an option also, but my suggestion above should work also.
Thanks for the pointer! I do believe it will make more sense to do it from linux itself unless we have no way to do it in linux.
> > Kevin
[0] Table 5-517. Description Of The Pad Configuration Register Bits https://www.ti.com/lit/pdf/spruid7
NOTE: The hardware works in such a way that as soon as the IO isolation is disabled the wake_evt information is lost so the pinctrl-single driver won't be able to know what pin woke it up if we disable io isolation before it has the chance to look at the padconf registers
-- Best regards, Dhruva Gole <d-gole@ti.com>
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