On 16 December 2015 at 12:40, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: > > On 16/12/15 09:47, Ulf Hansson wrote: >> On 16 December 2015 at 10:40, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: >>> Hi Ulf, >>> >>> On 15/12/15 19:54, Ulf Hansson wrote: >>>> On 4 December 2015 at 15:57, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: >>>>> Enable PM_GENERIC_DOMAINS for tegra 64-bit devices. To ensure that devices >>>>> dependent upon a particular power-domain are only probed when that power >>>>> domain has been powered up, requires that PM is made mandatory for tegra >>>>> 64-bit devices and so select this option for tegra as well. >>>>> >>>>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx> >>>>> --- >>>>> arch/arm64/Kconfig.platforms | 2 ++ >>>>> 1 file changed, 2 insertions(+) >>>>> >>>>> diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms >>>>> index 9806324fa215..e0b5bd0aff0f 100644 >>>>> --- a/arch/arm64/Kconfig.platforms >>>>> +++ b/arch/arm64/Kconfig.platforms >>>>> @@ -93,6 +93,8 @@ config ARCH_TEGRA >>>>> select GENERIC_CLOCKEVENTS >>>>> select HAVE_CLK >>>>> select PINCTRL >>>>> + select PM >>>>> + select PM_GENERIC_DOMAINS >>>> >>>> If you still want to allow ARCH_TEGRA to run without PM, you should >>>> probably change to: >>>> >>>> select PM_GENERIC_DOMAINS if PM >>> >>> Per the changelog this is deliberate. If we allow !PM, then there is a >>> potential that you could probe a device when the power domain is not >>> powered on. I understand that some SoCs turn on all the power-domains >>> when !PM but this will not work for tegra because we don't register the >>> power domain until later in the boot and so we are relying upon probe >>> deferral to defer the probe of devices that use power-domains. >> >> So what you are saying is that adding the PM domain support, will fix >> some devices to become successfully probed as they were broken before? > > Not exactly. There is a legacy tegra_powergate_sequence_power_up() that > has been used to date to get around this. However, by migrating to GENPD > we really need to make PM mandatory, otherwise you could attempt to > probe a device in a power domain that is not powered. In other words, > you are probing blindly. I know some SoCs do this, but that does not > seem very robust. Thank for the clarification. I agree. You may add my: Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
