Messages in this thread | | | Date | Mon, 26 Nov 2007 18:46:17 +0100 | From | Pierre Ossman <> | Subject | Re: mmc select voltage functionality |
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On Thu, 22 Nov 2007 05:34:11 -0800 (PST) Madhusudhan C <madhu_lkml@yahoo.com> wrote:
> Hi Pierre, > > I have a question on the mmc_select_voltage fn of the mmc core file drivers/mmc/core/core.c. > > During the power up sequence the mmc_power_up fn sets the OCR bit to setup 3V. Subsequentely the mmc_select_voltage fn selects the lowest voltage > the card can support.The host->ios.power_mode is not changed to MMC_POWER_UP before calling mmc_set_ios from this function hence the power_mode remains in MMC_POWER_ON state.So my question is, how should the controller driver handle this change in volatge. Under which case of power mode should the controller driver change the voltage again when a dual voltage card is detected? >
To be completely correct, the MMC layer should probably power down the card first, yes. Right now most drivers will handle all of these things as they see fit. Haven't seen a single bug report about it yet so...
Just change the voltage in whatever way makes sense for your controller.
Rgds -- -- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org PulseAudio, core developer http://pulseaudio.org rdesktop, core developer http://www.rdesktop.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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