On 10 July 2018 at 10:05, Lucas Stach <l.st...@pengutronix.de> wrote: > Am Dienstag, den 10.07.2018, 00:27 +0200 schrieb Ulf Hansson: >> > On 6 July 2018 at 18:46, Leonard Crestez <leonard.cres...@nxp.com> wrote: >> > On imx6qp power gating on the PU domain is disabled because of errata >> > ERR009619. However power gating during suspend/resume can still be >> > performed. >> >> Sounds a bit hand wavy. Exactly why can it be done during system >> suspend/resume? > > Power gating this domain in normal operation may introduce a glitch in > unrelated modules, potentially disturbing a running display scanout. > This is not a concern when the whole system enters suspend state, so > it's safe to do in this case.
Makes sense. Could we please fold this information into the commit message to make this clear!? > > Regards, > Lucas > >> > >> > Enable this by implementing SLEEP_PM_OPS in imx_pgc_power_domain_driver. >> > >> > In order to ensure correct ordering add device links from devices inside >> > the PU domain to the pgc platform_device. >> >> In genpd, the PM domain gets powered off after all device's >> corresponding ->suspend_noirq() callback has been invoked - and it >> also considers if there are some wakeup settings enabled, possibly >> avoiding to do the power off. >> >> It sound like the imx's power domain driver ->power_off|on() callback >> should deal with this, to make get a consistent behavior. I understand >> that you currently can't tell under what circumstances the >> ->power_off|on() callbacks are being invoked, that may need some >> changes in genpd. >> >> Currently we have a flag, GENPD_FLAG_ALWAYS_ON which makes genpd to >> always prevent power off. Perhaps we should add a new flag >> "GENPD_FLAG_RUNTIME_ON", which makes genpd to call the >> ->power_on|off() callbacks, but only during system wide PM. >> >> Thoughts? > > Yes, this might work for this case. Alright. I can help to implement, if you want. Just tell. Kind regards Uffe
