Messages in this thread | | | Date | Thu, 28 May 2015 10:02:47 +0200 | Subject | Re: [PATCH 2/2] mmc: sunxi: Also set SDXC_LOW_POWER_ON | From | Ulf Hansson <> |
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On 25 May 2015 at 09:02, Hans de Goede <hdegoede@redhat.com> wrote: > Hi, > > On 24-05-15 20:04, Michal Suchanek wrote: >> >> The function sunxi_mmc_oclk_onoff filters out the SDXC_LOW_POWER_ON flag >> but never sets it. >> >> Set SDXC_LOW_POWER_ON when oclk is disabled. > > > Nack, looking at the datasheet I do not thing this patch actually > does anything, according to the datasheet setting this bit to 1 results > in: "Turn off card clock when FSM in IDLE state", iow this does mmc clock > gating on idle automatically in hardware, since we completely disable the > clock on clock-off by clearing SDXC_CARD_CLOCK_ON setting this bit on > clock-off is a nop. > > We could consider actually setting this to safe power when setting the clock > on, for doing that it would be good to look at the android code and see if > it ever sets this bit and if so when. > > WRT CONFIG_MMC_CLKGATE we are probably better off using SDXC_LOW_POWER_ON > then that when it is enabled. So maybe we should set SDXC_LOW_POWER_ON > based on #ifdef WRT CONFIG_MMC_CLKGATE, and have some way to tell the > mmc core to not do clock gating on this host ?
I am planning to remove the entire thing for CONFIG_MMC_CLKGATE, maybe it's time to do that now!?
Most hosts use runtime PM to deal with clock gating at idle and browsing def configs tells me that CONFIG_MMC_CLKGATE isn't much used.
Kind regards Uffe
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