Hi, On Sat, Apr 26, 2014 at 5:00 AM, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote: > > > On 24.04.2014 13:03, Tushar Behera wrote: >> >> On 04/24/2014 03:36 PM, Tomasz Figa wrote: >>> >>> On 24.04.2014 11:07, Tushar Behera wrote: >>>> >>>> On 04/23/2014 03:43 PM, Kukjin Kim wrote: >>>>> >>>>> Tushar Behera wrote: >>>>>> >>>>>> >>>>>> On 22 April 2014 13:08, Alim Akhtar <alim.akhtar@xxxxxxxxx> wrote: >>>>>>> >>>>>>> Hi Tushar >>>>>>> >>>>>>> On Tue, Apr 22, 2014 at 11:09 AM, Tushar Behera >>>>>>> <tushar.behera@xxxxxxxxxx> wrote: >>>>>>>> >>>>>>>> MAU powerdomain provides clocks for Audio sub-system block. This >>>>>>>> block >>>>>>>> comprises of the I2S audio controller, audio DMA blocks and Audio >>>>>>>> sub-system clock registers. >>>>>>>> >>>>>>>> Right now, there is no way to hook up power-domains with clock >>>>>> >>>>>> providers. >>>>>>>> >>>>>>>> During late boot when this power-domain gets disabled, we get >>>>>>>> following >>>>>>>> external abort. >>>>> >>>>> >>>>> + Jonghwan Choi >>>>> >>>>> Well, this is not a perfect solution to support MAU power domain, >>>>> it's true it is a problem right now though. >>>>> >>>>> In other words, this is just temporal fix for the problem. >>>>> >>>>> How about accessing clock stuff for audio sub-system with handling >>>>> MAU power domain via generic IO power domain? >>>>> >>>> >>>> + Tomasz Figa >>>> >>>> Existing power domain driver exynos4_pm_init_power_domain is registered >>>> with an arch_initcall whereas the clk-exynos-audss driver is registered >>>> with core_initcall. Hence even if add mau_pd node to clk-exynos-audss >>>> node, the binding with power-domain doesn't happen. >>> >>> >>> I'd say core_initcall is way too early for clk-exynos-audss driver. It >>> should be at most subsys_initcall. As far as I can see, all users of >>> clocks provided by this driver (i.e. i2s) are probed at device_initcall >>> level anyway. >>> >> >> It is also used by ADMA node, which gets probed. > > > If I'm looking correctly, ADMA is handled by pl330 driver which is > registered at device_initcall level and so it shouldn't make problems with > clk-exynos-audss driver being probed at subsys_initcall level. > > >> >>>> >>>> Alternately, if Tomasz's patches are applied [1], power-domain binding >>>> is successful. But because of the init order, clk-exynos-audss defers >>>> probe resulting in a kernel crash. Forcing clk-exynos-audss to register >>>> through arch_initcall() fixes this issue, but I am not sure if that is >>>> okay. >>> >>> >>> If the driver crashes on deferred probe, then it's a bug and it should >>> be fixed. >>> >> >> By the time clk-exynos-audss is getting called, mau_pd is already >> disabled by power-domain driver. That is not getting enabled during >> clk-exynos-audss probe. Am I missing something? > > > Probably. The driver should enable runtime PM and call pm_runtime_get_sync() > to make sure that power is supplied to the device it accesses. > > By the way, if defining MAU power domain in DT, then also all the devices > inside of this domain should be bound to it, including ADMA and I2S, but I > don't see neither of them having the "samsung,power-domain" property. > According to UM of 5420, MAU has to be power gated is specific order the SYS_PWR_CFG field of EXYNOS5_PAD_RETENTION_MAU_SYS_PWR_REG should be set to 0, before actually power gating the MAU block. I am NOT sure whether this is taken care in the mainline. As per the current implementation in pm_domain.c, the exynos_pd_power() just writes __raw_writel(pwr, base); based on bool power_on passed. We dont have the provision in the generic power domain framework to have something like pre_power_off() or post_power_on(). Correct me if am wrong. Even for power gating of ISP block a certain specific order needs to be followed. So I think there is a need ops like pre_power_off(), post_power_on() in generic power domain framework. let me know your opinion. > Best regards, > Tomasz > > -- > To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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