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Commit 0797e5f1 authored by Johan Rudholm's avatar Johan Rudholm Committed by Chris Ball
Browse files

mmc: core: Fixup signal voltage switch 



When switching SD and SDIO cards from 3.3V to 1.8V signal levels, the
clock should be gated for 5 ms during the step. After enabling the
clock, the host should wait for at least 1 ms before checking for
failure. Failure by the card to switch is indicated by dat[0:3] being
pulled low. The host should check for this condition and power-cycle
the card if failure is indicated.

Add a retry mechanism for the SDIO case.

If the voltage switch fails repeatedly, give up and continue the
initialization using the original voltage.

This patch places a couple of requirements on the host driver:

 1) mmc_set_ios with ios.clock = 0 must gate the clock
 2) mmc_power_off must actually cut the power to the card
 3) The card_busy host_ops member must be implemented

if these requirements are not fulfilled, the 1.8V signal voltage switch
will still be attempted but may not be successful.

Signed-off-by: default avatarJohan Rudholm <johan.rudholm@stericsson.com>
Signed-off-by: default avatarKevin Liu <kliu5@marvell.com>
Acked-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Tested-by: default avatarWei WANG <wei_wang@realsil.com.cn>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent 567c8903

drivers/mmc/core/core.c

+73 −10
Original line number Diff line number Diff line
@@ -1340,6 +1340,7 @@ int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage) 
{

	struct mmc_command cmd = {0};

	int err = 0;

	u32 clock;



	BUG_ON(!host);
@@ -1347,7 +1348,19 @@ int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage) 
	 * Send CMD11 only if the request is to switch the card to

	 * 1.8V signalling.

	 */

	if (signal_voltage != MMC_SIGNAL_VOLTAGE_330) {

	if (signal_voltage == MMC_SIGNAL_VOLTAGE_330)

		return __mmc_set_signal_voltage(host, signal_voltage);



	/*

	 * If we cannot switch voltages, return failure so the caller

	 * can continue without UHS mode

	 */

	if (!host->ops->start_signal_voltage_switch)

		return -EPERM;

	if (!host->ops->card_busy)

		pr_warning("%s: cannot verify signal voltage switch\n",

				mmc_hostname(host));



	cmd.opcode = SD_SWITCH_VOLTAGE;

	cmd.arg = 0;

	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
@@ -1358,9 +1371,59 @@ int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage) 


	if (!mmc_host_is_spi(host) && (cmd.resp[0] & R1_ERROR))

		return -EIO;



	mmc_host_clk_hold(host);

	/*

	 * The card should drive cmd and dat[0:3] low immediately

	 * after the response of cmd11, but wait 1 ms to be sure

	 */

	mmc_delay(1);

	if (host->ops->card_busy && !host->ops->card_busy(host)) {

		err = -EAGAIN;

		goto power_cycle;

	}

	/*

	 * During a signal voltage level switch, the clock must be gated

	 * for 5 ms according to the SD spec

	 */

	clock = host->ios.clock;

	host->ios.clock = 0;

	mmc_set_ios(host);



	return __mmc_set_signal_voltage(host, signal_voltage);

	if (__mmc_set_signal_voltage(host, signal_voltage)) {

		/*

		 * Voltages may not have been switched, but we've already

		 * sent CMD11, so a power cycle is required anyway

		 */

		err = -EAGAIN;

		goto power_cycle;

	}



	/* Keep clock gated for at least 5 ms */

	mmc_delay(5);

	host->ios.clock = clock;

	mmc_set_ios(host);



	/* Wait for at least 1 ms according to spec */

	mmc_delay(1);



	/*

	 * Failure to switch is indicated by the card holding

	 * dat[0:3] low

	 */

	if (host->ops->card_busy && host->ops->card_busy(host))

		err = -EAGAIN;



power_cycle:

	if (err) {

		pr_debug("%s: Signal voltage switch failed, "

			"power cycling card\n", mmc_hostname(host));

		mmc_power_cycle(host);

	}



	mmc_host_clk_release(host);



	return err;

}



/*

drivers/mmc/core/sd.c

+16 −5
Original line number Diff line number Diff line
@@ -712,6 +712,14 @@ int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr) 
{

	int err;

	u32 max_current;

	int retries = 10;



try_again:

	if (!retries) {

		ocr &= ~SD_OCR_S18R;

		pr_warning("%s: Skipping voltage switch\n",

			mmc_hostname(host));

	}



	/*

	 * Since we're changing the OCR value, we seem to
@@ -733,9 +741,10 @@ int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr) 


	/*

	 * If the host supports one of UHS-I modes, request the card

	 * to switch to 1.8V signaling level.

	 * to switch to 1.8V signaling level. If the card has failed

	 * repeatedly to switch however, skip this.

	 */

	if (mmc_host_uhs(host))

	if (retries && mmc_host_uhs(host))

		ocr |= SD_OCR_S18R;



	/*
@@ -746,7 +755,6 @@ int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr) 
	if (max_current > 150)

		ocr |= SD_OCR_XPC;



try_again:

	err = mmc_send_app_op_cond(host, ocr, rocr);

	if (err)

		return err;
@@ -758,8 +766,11 @@ int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr) 
	if (!mmc_host_is_spi(host) && rocr &&

	   ((*rocr & 0x41000000) == 0x41000000)) {

		err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180);

		if (err) {

			ocr &= ~SD_OCR_S18R;

		if (err == -EAGAIN) {

			retries--;

			goto try_again;

		} else if (err) {

			retries = 0;

			goto try_again;

		}

	}

drivers/mmc/core/sdio.c

+18 −2
Original line number Diff line number Diff line
@@ -584,10 +584,19 @@ static int mmc_sdio_init_card(struct mmc_host *host, u32 ocr, 
{

	struct mmc_card *card;

	int err;

	int retries = 10;



	BUG_ON(!host);

	WARN_ON(!host->claimed);



try_again:

	if (!retries) {

		pr_warning("%s: Skipping voltage switch\n",

				mmc_hostname(host));

		ocr &= ~R4_18V_PRESENT;

		host->ocr &= ~R4_18V_PRESENT;

	}



	/*

	 * Inform the card of the voltage

	 */
@@ -646,9 +655,16 @@ static int mmc_sdio_init_card(struct mmc_host *host, u32 ocr, 
	 * systems that claim 1.8v signalling in fact do not support

	 * it.

	 */

	if ((ocr & R4_18V_PRESENT) && mmc_host_uhs(host)) {

	if (!powered_resume && (ocr & R4_18V_PRESENT) && mmc_host_uhs(host)) {

		err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180);

		if (err) {

		if (err == -EAGAIN) {

			sdio_reset(host);

			mmc_go_idle(host);

			mmc_send_if_cond(host, host->ocr_avail);

			mmc_remove_card(card);

			retries--;

			goto try_again;

		} else if (err) {

			ocr &= ~R4_18V_PRESENT;

			host->ocr &= ~R4_18V_PRESENT;

		}