On 2 June 2017 at 10:47, Geert Uytterhoeven [off-list ref] wrote:
Hi Wolfram, Ulf, Simon,
While investigating suspend/resume for the R-Car Gen3 clock driver, I
noticed a clock imbalance for SDHI on Salvator-X.
After boot:
# head -2 /sys/kernel/debug/clk/clk_summary
clock enable_cnt prepare_cnt rate accuracy phase
-------------------------------------------------------------
# grep sd /sys/kernel/debug/clk/clk_summary
.sdsrc 3 3 399999984 0 0
sd3 1 1 6250000 0 0
sdif3 1 2 6250000 0 0
sd2 1 1 199999992 0 0
sdif2 1 2 199999992 0 0
sd1 0 0 199999992 0 0
sdif1 0 0 199999992 0 0
sd0 1 1 6250000 0 0
sdif0 1 2 6250000 0 0
After s2idle suspend/resume:
# grep sd /sys/kernel/debug/clk/clk_summary
.sdsrc 3 3 399999984 0 0
sd3 1 1 6250000 0 0
sdif3 2 2 6250000 0 0
sd2 1 1 199999992 0 0
sdif2 2 2 199999992 0 0
sd1 0 0 199999992 0 0
sdif1 0 0 199999992 0 0
sd0 1 1 6250000 0 0
sdif0 2 2 6250000 0 0
Enable counts are 1 before suspend, and 2 after resume.
Boot: Enabled once (also at hardware level):
platform_drv_probe
4 more quoted lines
The driver calls pm_runtime_set_active() during ->probe(), which means
genpd's ->runtime_resume() callback isn't invoked during that point.
In other words, the clocks managed by the clock domain isn't enabled
during ->probe() as genpd's doesn't get to run pm_clk_resume() from
its ->runtime_resume() callback. Unless I am missing something. :-)
I think this is the reason to the following problems. How to fix it?
The driver needs to call pm_runtime_get_sync() instead of
pm_runtime_set_active(), however that may requires some careful
changes if one wants the driver to be able to enable clocks also when
CONFIG_PM is unset. If not, it's pretty easy, else I would do
something like below.
Add a "init" flag to host struct, and set that flag before calling
pm_runtime_get_sync() in ->probe(). When the driver's
->runtime_resume() callbacks get called when the "init" flag is set,
just do an early return 0, as t means ->probe() is running and has
already taken care of the enabling the clock. When probe is done, and
before dropping runtime usage count with pm_runtime_put(), reset the
"init" flag.
Suspend: Disabled once (also at hardware level):
suspend_devices_and_enter
dpm_suspend_start
dpm_suspend
__device_suspend
dpm_run_callback
pm_runtime_force_suspend
genpd_runtime_suspend
pm_generic_runtime_suspend
tmio_mmc_host_runtime_suspend
renesas_sdhi_clk_disable
Resume: Enabled twice (first one enables at hardware level):
dpm_resume_noirq
device_resume_noirq
dpm_run_callback
pm_genpd_resume_noirq
pm_runtime_force_resume
genpd_runtime_resume
genpd_start_dev
pm_clk_resume (1)
__genpd_runtime_resume
pm_generic_runtime_resume
tmio_mmc_host_runtime_resume
renesas_sdhi_clk_enable (2)
During subsequent suspends, the clock is disabled twice (last one disables
at hardware level), as expected:
suspend_devices_and_enter
dpm_suspend_start
dpm_suspend
__device_suspend
dpm_run_callback
31 more quoted lines
Kind regards
Uffe