From: Philip Rakity <prakity@marvell.com>
To: zhangfei gao <zhangfei.gao@gmail.com>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
Bing Zhao <bzhao@marvell.com>, Frank Huang <frankh@marvell.com>
Subject: Re: [PATCH 2/2] ARM: mmp2: support sdio device 8787
Date: Wed, 27 Jul 2011 21:23:18 -0700 [thread overview]
Message-ID: <B6C7F083-E557-418D-9136-A37189F2770D@marvell.com> (raw)
In-Reply-To: <CAMj5BkgEWb4ejChy6NCdxLse9maG25Pr6JmTS3pt0HJk2ee1Eg@mail.gmail.com>
On Jul 27, 2011, at 7:44 PM, zhangfei gao wrote:
>>> +
>>> +static struct fixed_voltage_config sdio_power = {
>>> + .supply_name = "vmmc",
>>> + .microvolts = 3000000,
>>> + .gpio = mfp_to_gpio(MFP_PIN_GPIO57),
>>> + .enable_high = 1,
>>> + .enabled_at_boot = 0,
>>> + .init_data = &sdio_power_data,
>>> +};
>>> +
>>
>> ldo7 is the power source. The 8787 is the consumer and the code should reflect this.
>> GPIO57 is an on/off switch to the 8787.
>>
>>
> Instead of LDO7, 8787 is powered with V_SD2, V_BATT, and VLDO12 on brownstone.
> Use PDn to control 8787 power is recommended method.
> 1. Some LDO is shared and can not be cut down.
> 2. Control LDO is much slower, some time is needed for voltage to
> decay, and the time is not accurate to control.
> 3. With LDO powered, 8787 is under control and 8787 could put itself
> to the lowest state.
LDO is dedicated to 8787 and can be left on. The power picture is ldo (as regulator)
and 8787 as consumer. Code does not show this relationship. The 8787 in deep sleep
draws very little power but since even this small power usage is a concern the disabling
the ldo can reduce power further.
next prev parent reply other threads:[~2011-07-28 4:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1654B53E-123B-43F5-B526-49D19D39D1F0@marvell.com>
2011-07-27 17:57 ` [PATCH 2/2] ARM: mmp2: support sdio device 8787 Philip Rakity
2011-07-28 2:44 ` zhangfei gao
2011-07-28 4:23 ` Philip Rakity [this message]
2011-07-28 5:36 ` zhangfei gao
2011-07-26 7:06 [PATCH v2 0/2] set_ios handle vmmc Zhangfei Gao
2011-07-26 7:06 ` [PATCH 2/2] ARM: mmp2: support sdio device 8787 Zhangfei Gao
2011-07-26 7:06 ` Zhangfei Gao
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