Re: [PATCH 5/8] omap_hsmmc: RX51: set padconfs to pull down when powering off eMMC

From: Adrian Hunter <adrian.hunter@nokia.com>
To: Nishanth Menon <nm@ti.com>
Cc: Tony Lindgren <tony@atomide.com>,
	linux-mmc Mailing List <linux-mmc@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-omap Mailing List <linux-omap@vger.kernel.org>,
	"Chikkature Rajashekar, Madhusudhan" <madhu.cr@ti.com>
Subject: Re: [PATCH 5/8] omap_hsmmc: RX51: set padconfs to pull down when powering off eMMC
Date: Thu, 14 Jan 2010 09:57:22 +0200	[thread overview]
Message-ID: <4B4ECE62.5030408@nokia.com> (raw)
In-Reply-To: <4B4E57A5.4050400@ti.com>

Nishanth Menon wrote:
> Tony Lindgren had written, on 01/13/2010 03:00 PM, the following:
>> * Tony Lindgren <tony@atomide.com> [100113 12:38]:
>>> * Tony Lindgren <tony@atomide.com> [100113 12:36]:
>>>> You might want to check what happens in omap off-idle mode in these cases
>>>> and see if enabling OMAP_PIN_OFF_INPUT_PULLDOWN makes any difference in
>>>> power consumption in off state. That probably does not matter unless the
>>>> floating lines cause the eMMC to do something on it's own :)
>>> Or OMAP_PIN_OFF_OUTPUT_LOW actually.
>> One more time.. Most likely OMAP_PIN_OFF_INPUT_PULLDOWN is safer
>> in general as the OMAP_PIN_OFF_OUTPUT_LOW does not work for all
>> pins. According to the TRM, OMAP_PIN_OFF_OUTPUT_LOW only works
>> for pins where at least one of the mux modes supports output
>> mode.
> 
> is'nt vaux/vmmc/whatever voltage to eMMC shutoff for the device on the 
> board in off mode? I wonder why the behavior is seen. The only thing 
> that I am worried is that the board potentially will draw more current 
> as the lines are driven low.

OMAP is not OFF just the eMMC.  Current is sucked out of the data lines
through the eMMC to the regulator which is off.