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Commit 611766c0 authored by Asutosh Das's avatar Asutosh Das Committed by Krishna Konda
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mmc: core: add clock-scaling support to HS400 cards 



This patch adds clock scaling support to HS400 cards.
Scaling down to 52MHz from HS400 involves:
 - switching the bus-speed mode to HS at 52MHz

Scaling up to HS400 would require all of the initialization
process upto HS400 mode selection.

Change-Id: I8196d6666bcc0ef327659253df53a17792fa51f7
Signed-off-by: default avatarAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: default avatarKrishna Konda <kkonda@codeaurora.org>
parent 4b2d5f30

drivers/mmc/core/core.c

+13 −1
Original line number Diff line number Diff line
@@ -2824,13 +2824,19 @@ EXPORT_SYMBOL_GPL(mmc_reset_clk_scale_stats); 
unsigned long mmc_get_max_frequency(struct mmc_host *host)

{

	unsigned long freq;

	unsigned char timing;



	if (host->ops && host->ops->get_max_frequency) {

		freq = host->ops->get_max_frequency(host);

		goto out;

	}



	switch (host->ios.timing) {

	if (mmc_card_hs400(host->card))

		timing = MMC_TIMING_MMC_HS400;

	else

		timing = host->ios.timing;



	switch (timing) {

	case MMC_TIMING_UHS_SDR50:

		freq = UHS_SDR50_MAX_DTR;

		break;
@@ -2843,6 +2849,9 @@ unsigned long mmc_get_max_frequency(struct mmc_host *host) 
	case MMC_TIMING_UHS_DDR50:

		freq = UHS_DDR50_MAX_DTR;

		break;

	case MMC_TIMING_MMC_HS400:

		freq = MMC_HS400_MAX_DTR;

		break;

	default:

		mmc_host_clk_hold(host);

		freq = host->ios.clock;
@@ -2883,6 +2892,9 @@ static unsigned long mmc_get_min_frequency(struct mmc_host *host) 
	case MMC_TIMING_MMC_HS200:

		freq = MMC_HIGH_52_MAX_DTR;

		break;

	case MMC_TIMING_MMC_HS400:

		freq = MMC_HIGH_52_MAX_DTR;

		break;

	case MMC_TIMING_UHS_DDR50:

		freq = UHS_DDR50_MAX_DTR / 2;

		break;

drivers/mmc/core/mmc.c

+28 −3
Original line number Diff line number Diff line
@@ -1179,6 +1179,26 @@ out: 
	return err;

}



int mmc_set_clock_bus_speed(struct mmc_card *card, unsigned long freq)

{

	int err;



	if (freq < MMC_HS400_MAX_DTR) {

		/*

		 * Lower the clock and adjust the timing to be able

		 * to switch to HighSpeed mode

		 */

		mmc_set_timing(card->host, MMC_TIMING_LEGACY);

		mmc_set_clock(card->host, MMC_HIGH_26_MAX_DTR);



		err = mmc_select_hs(card, &card->cached_ext_csd);

	} else {

		err = mmc_select_hs400(card, &card->cached_ext_csd);

	}



	return err;

}



/**

 * mmc_change_bus_speed() - Change MMC card bus frequency at runtime

 * @host: pointer to mmc host structure
@@ -1214,8 +1234,6 @@ static int mmc_change_bus_speed(struct mmc_host *host, unsigned long *freq) 
			|| mmc_card_hs400(card)) {

		if (*freq > card->ext_csd.hs_max_dtr)

			*freq = card->ext_csd.hs_max_dtr;

		if (mmc_card_highspeed(card) && (*freq > 52000000))

			*freq = 52000000;

	} else if (*freq > card->csd.max_dtr) {

		*freq = card->csd.max_dtr;

	}
@@ -1223,7 +1241,13 @@ static int mmc_change_bus_speed(struct mmc_host *host, unsigned long *freq) 
	if (*freq < host->f_min)

		*freq = host->f_min;



	if (mmc_card_hs400(card)) {

		err = mmc_set_clock_bus_speed(card, *freq);

		if (err)

			goto out;

	} else {

		mmc_set_clock(host, (unsigned int) (*freq));

	}



	if ((mmc_card_hs400(card) || mmc_card_hs200(card))

		&& card->host->ops->execute_tuning) {
@@ -1414,6 +1438,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, 
		err = mmc_get_ext_csd(card, &ext_csd);

		if (err)

			goto free_card;

		memcpy(&card->cached_ext_csd, ext_csd, sizeof(card->ext_csd));

		err = mmc_read_ext_csd(card, ext_csd);

		if (err)

			goto free_card;

include/linux/mmc/card.h

+1 −0
Original line number Diff line number Diff line
@@ -394,6 +394,7 @@ struct mmc_card { 
	unsigned int		idle_timeout;

	struct notifier_block        reboot_notify;

	bool issue_long_pon;

	u8 cached_ext_csd;

};



/*