Commit ae628903 authored by Pierre Ossman's avatar Pierre Ossman
Browse files

sdhci: avoid changing voltage needlessly 



Because of granularity issues, sometimes we told the hardware to change
to the voltage we were already at. Rework the logic so this doesn't
happen.

Signed-off-by: default avatarPierre Ossman <pierre@ossman.eu>
parent 7ceeb6a4

drivers/mmc/host/sdhci.c

+28 −25
Original line number Diff line number Diff line
@@ -1005,50 +1005,53 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned short power) 
{

	u8 pwr;



	if (host->power == power)

		return;



	if (power == (unsigned short)-1) {

		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);

		goto out;

	}



	/*

	 * Spec says that we should clear the power reg before setting

	 * a new value. Some controllers don't seem to like this though.

	 */

	if (!(host->quirks & SDHCI_QUIRK_SINGLE_POWER_WRITE))

		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);



	pwr = SDHCI_POWER_ON;



	if (power == (unsigned short)-1)

		pwr = 0;

	else {

		switch (1 << power) {

		case MMC_VDD_165_195:

		pwr |= SDHCI_POWER_180;

			pwr = SDHCI_POWER_180;

			break;

		case MMC_VDD_29_30:

		case MMC_VDD_30_31:

		pwr |= SDHCI_POWER_300;

			pwr = SDHCI_POWER_300;

			break;

		case MMC_VDD_32_33:

		case MMC_VDD_33_34:

		pwr |= SDHCI_POWER_330;

			pwr = SDHCI_POWER_330;

			break;

		default:

			BUG();

		}

	}



	if (host->pwr == pwr)

		return;



	host->pwr = pwr;



	if (pwr == 0) {

		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);

		return;

	}



	/*

	 * Spec says that we should clear the power reg before setting

	 * a new value. Some controllers don't seem to like this though.

	 */

	if (!(host->quirks & SDHCI_QUIRK_SINGLE_POWER_WRITE))

		sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);



	/*

	 * At least the Marvell CaFe chip gets confused if we set the voltage

	 * and set turn on power at the same time, so set the voltage first.

	 */

	if ((host->quirks & SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER))

		sdhci_writeb(host, pwr & ~SDHCI_POWER_ON, SDHCI_POWER_CONTROL);



		sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);



out:

	host->power = power;

	pwr |= SDHCI_POWER_ON;



	sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);

}



/*****************************************************************************\

drivers/mmc/host/sdhci.h

+1 −1
Original line number Diff line number Diff line
@@ -255,7 +255,7 @@ struct sdhci_host { 
	unsigned int		timeout_clk;	/* Timeout freq (KHz) */



	unsigned int		clock;		/* Current clock (MHz) */

	unsigned short		power;		/* Current voltage */

	u8			pwr;		/* Current voltage */



	struct mmc_request	*mrq;		/* Current request */

	struct mmc_command	*cmd;		/* Current command */