On Jan 6, 2011, at 2:44 AM, zhangfei gao wrote:
> On Wed, Jan 5, 2011 at 11:30 AM, Philip Rakity <prakity@xxxxxxxxxxx> wrote:
>>
>> On Jan 5, 2011, at 1:39 AM, zhangfei gao wrote:
>>
>>> From 7554ead744bfdc7304a7ae9fb227212bf548161a Mon Sep 17 00:00:00 2001
>>> From: Zhangfei Gao <zhangfei.gao@xxxxxxxxxxx>
>>> Date: Wed, 5 Jan 2011 17:21:00 -0500
>>> Subject: [PATCH] mmc: sdhci stop SDCLK during asynchronous interrupt peroid
>>>
>>> V3 controller could stop SDCLK during asynchronous interrupt peroid
>>> to save power, via set SDHCI_CTRL2_AINT bit 14 of
>>> SDHCI_HOST_CONTROL2(0x3e)
>>> Two conditions:
>>> 1. card support asynchronous interrupt
>>> 2. Asynchronous interrupt support is set to 1 in the capabilities register.
>>>
>>> How to enable: mmc->caps |= MMC_CAP_CLOCK_GATE
>>>
>>> Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxxx>
>>> ---
>>> drivers/mmc/host/sdhci.c | 14 ++++++++++++++
>>> drivers/mmc/host/sdhci.h | 2 ++
>>> include/linux/mmc/host.h | 2 ++
>>> 3 files changed, 18 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index aafbb42..946b947 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -1261,6 +1261,15 @@ static void sdhci_set_ios(struct mmc_host *mmc,
>>> struct mmc_ios *ios)
>>> if(host->quirks & SDHCI_QUIRK_RESET_CMD_DATA_ON_IOS)
>>> sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
>>>
>>> + if (mmc->caps & MMC_CAP_CLOCK_GATE) {
>>> + u16 con;
>>> +
>>> + con = readw(host->ioaddr + SDHCI_HOST_CONTROL2);
>>> + con |= SDHCI_CTRL2_AINT;
>>> + writew(con, host->ioaddr + SDHCI_HOST_CONTROL2);
>>> + }
>>> +
>>> +
>>
>>
>> This will enable clock gating for SD/eMMC and SDIO cards. This is not a good idea for SDIO where
>> there are known issues. This is one reason the software clock gating code does not enable
>> clock gating on SDIO. Not all SDIO cards can work.
>
> It is enabled only by setting caps MMC_CAP_CLOCK_GATE, for example the
> code to verify emmc/sd in sdhci-pxa.c
>
> if (pdata && pdata->flags & PXA_FLAG_CONTROL_CLK_GATE) {
> /* v3 controller could support clock gating */
> host->mmc->caps |= MMC_CAP_CLOCK_GATE;
> }
> SDIO is not enabled since no PXA_FLAG_CONTROL_CLK_GATE in flags.
> In the experiment, we find sdio (wifi) power does not change a lot
> with or without clock gate, it mainly rely on wifi itself, for example
> wifi goto deep sleep mode.
>
how do you know what card will be plugged in ? this only works work hard wired cards not for cards plugged into a slot.
>>
>> It does not handle the case clock gating being supported in pre SD 3.0 controllers.
> It is true, soft clock gating also be verified in SD 2.0 controller,
> such as pxa955.
>
>>
>> See my patch on h/w clock gating -- if there are issues with the patch would appreciate comments.
>>
>>> out:
>>> mmiowb();
>>> spin_unlock_irqrestore(&host->lock, flags);
>>> @@ -1808,6 +1817,11 @@ int sdhci_add_host(struct sdhci_host *host)
>>> mmc->caps |= (MMC_CAP_1_8V_DDR);
>>> }
>>>
>>> + if (mmc->caps & MMC_CAP_CLOCK_GATE) {
>>> + if (!(caps & SDHCI_CAN_ASYN_INT))
>>> + mmc->caps &= ~MMC_CAP_CLOCK_GATE;
>>> + }
>>> +
>>> if (host->quirks & SDHCI_QUIRK_FORCE_DMA)
>>> host->flags |= SDHCI_USE_SDMA;
>>> else if (!(caps & SDHCI_CAN_DO_SDMA))
>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>> index c4bd5dd..907de87 100644
>>> --- a/drivers/mmc/host/sdhci.h
>>> +++ b/drivers/mmc/host/sdhci.h
>>> @@ -153,6 +153,7 @@
>>> #define SDHCI_CTRL2_SDR104 0x0003
>>> #define SDHCI_CTRL2_DDR50 0x0004
>>> #define SDHCI_CTRL2_1_8V 0x0008
>>> +#define SDHCI_CTRL2_AINT 0x4000
>>>
>>> #define SDHCI_CAPABILITIES 0x40
>>> #define SDHCI_TIMEOUT_CLK_MASK 0x0000003F
>>> @@ -172,6 +173,7 @@
>>> #define SDHCI_CAN_VDD_300 0x02000000
>>> #define SDHCI_CAN_VDD_180 0x04000000
>>> #define SDHCI_CAN_64BIT 0x10000000
>>> +#define SDHCI_CAN_ASYN_INT 0x20000000
>>>
>>> #define SDHCI_CAPABILITIES_1 0x44
>>> #define SDHCI_CAN_SDR50 0x00000001
>>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>>> index bcb793e..2a53a94 100644
>>> --- a/include/linux/mmc/host.h
>>> +++ b/include/linux/mmc/host.h
>>> @@ -173,6 +173,8 @@ struct mmc_host {
>>> /* DDR mode at 1.2V */
>>> #define MMC_CAP_POWER_OFF_CARD (1 << 13) /* Can power off after boot */
>>> #define MMC_CAP_BUS_WIDTH_TEST (1 << 14) /* CMD14/CMD19 bus width ok */
>>> +#define MMC_CAP_CLOCK_GATE (1 << 15) /* V3 controller */
>>> + /* support clock gating */
>>>
>>> mmc_pm_flag_t pm_caps; /* supported pm features */
>>>
>>> --
>>> 1.7.0.4
>>> --
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>>
>>
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