Commit fa550189 authored by Ulf Hansson's avatar Ulf Hansson Committed by Chris Ball
Browse files

mmc: core: Prevent eMMC VCC supply to be cut from late init 



For eMMC cards that has been initialized from a bootloader,
the VCC voltage supply must not be cut in an uncontrolled
manner, without first sending SLEEP or POWEROFF_NOTIFY.

The regulator_init_complete late initcall, may cut the VCC
regulator if it's reference counter is zero. To be able to
prevent the regulator from being cut, mmc_start_host, which
should execute at device init and thus before late init,
calls mmc_power_up. Then the host driver is able to increase
the reference to the regulator.

Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent 95dcc2cb

drivers/mmc/core/core.c

+15 −3
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ 
#include "sdio_ops.h"



static struct workqueue_struct *workqueue;

static const unsigned freqs[] = { 400000, 300000, 200000, 100000 };



/*

 * Enabling software CRCs on the data blocks can be a significant (30%)
@@ -1157,6 +1158,9 @@ static void mmc_power_up(struct mmc_host *host) 
{

	int bit;



	if (host->ios.power_mode == MMC_POWER_ON)

		return;



	mmc_host_clk_hold(host);



	/* If ocr is set, we use it */
@@ -1199,6 +1203,10 @@ static void mmc_power_up(struct mmc_host *host) 
void mmc_power_off(struct mmc_host *host)

{

	int err = 0;



	if (host->ios.power_mode == MMC_POWER_OFF)

		return;



	mmc_host_clk_hold(host);



	host->ios.clock = 0;
@@ -2005,7 +2013,6 @@ EXPORT_SYMBOL(mmc_detect_card_removed); 


void mmc_rescan(struct work_struct *work)

{

	static const unsigned freqs[] = { 400000, 300000, 200000, 100000 };

	struct mmc_host *host =

		container_of(work, struct mmc_host, detect.work);

	int i;
@@ -2044,8 +2051,12 @@ void mmc_rescan(struct work_struct *work) 
	 */

	mmc_bus_put(host);



	if (host->ops->get_cd && host->ops->get_cd(host) == 0)

	if (host->ops->get_cd && host->ops->get_cd(host) == 0) {

		mmc_claim_host(host);

		mmc_power_off(host);

		mmc_release_host(host);

		goto out;

	}



	mmc_claim_host(host);

	for (i = 0; i < ARRAY_SIZE(freqs); i++) {
@@ -2063,7 +2074,8 @@ void mmc_rescan(struct work_struct *work) 


void mmc_start_host(struct mmc_host *host)

{

	mmc_power_off(host);

	host->f_init = max(freqs[0], host->f_min);

	mmc_power_up(host);

	mmc_detect_change(host, 0);

}

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