lkml.org 
[lkml]   [2007]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: mmc select voltage functionality
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/

\
 
 \ /
  Last update: 2007-11-26 18:49    [W:0.132 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site