Hi, Ulf, Please, do you have any input/suggestions on this? Thank you, Claudiu Beznea On 19.06.2024 15:09, Claudiu wrote: > From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx> > > Hi, > > Watchdog device available on RZ/G3S SoC is part of a software-controlled > power domain. The watchdog driver implements struct > watchdog_ops::restart() handler which is called in atomic context via > this call chain: > > kernel_restart() -> > machine_restart() -> > do_kernel_restart() -> > atomic_notifier_call_chain() -> > watchdog_restart_notifier() > rzg2l_wdt_restart() > > When the rzg2l_wdt_restart() is called it may happen that the watchdog > clocks to be disabled and the associated power domain to be off. > Accessing watchdog registers in this state leads to aborts and system > blocks. > > To solve this issue the series proposes a new API called > dev_pm_genpd_resume_restart_dev() that is intended to be called in > scenarios like this. In this RFC series the > dev_pm_genpd_resume_restart_dev() checks if the system is in > SYSTEM_RESTART context and call dev_pm_genpd_resume(). I also wanted to > mark the device as a restart device with a new member in struct dev_pm_info > (similar to struct dev_pm_info::syscore) and check it in the newly > introduced API but then I told myself maybe it would be better to keep it > simpler for the moment. > > Please let me know how do you consider this. > > Along with it, series addresses the usage of clk_prepare_enable() in > rzg2l_wdt_restart() reported by Ulf Hansson at [1] and use the > dev_pm_genpd_resume_restart_dev() in rzg2l_wdt driver. > > Please note that series is built on top of [1]. > > A similar approach (using directly the dev_pm_genpd_resume() function in > rzg2l_wdt was proposed at [2]). This series was posted separatelly to > avoid blocking the initial support for the RZ/G3S SoC. > > Thank you, > Claudiu Beznea > > [1] https://lore.kernel.org/all/20240531065723.1085423-1-claudiu.beznea.uj@xxxxxxxxxxxxxx/ > [2] https://lore.kernel.org/all/20240410134044.2138310-10-claudiu.beznea.uj@xxxxxxxxxxxxxx/ > > Claudiu Beznea (3): > pmdomain: core: Add a helper to power on the restart devices > watchdog: rzg2l_wdt: Keep the clocks prepared > watchdog: rzg2l_wdt: Power on the PM domain in rzg2l_wdt_restart() > > drivers/pmdomain/core.c | 18 +++++++++++++++ > drivers/watchdog/rzg2l_wdt.c | 43 +++++++++++++++++++++++++++++++----- > include/linux/pm_domain.h | 2 ++ > 3 files changed, 58 insertions(+), 5 deletions(-) >
