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mmc: core: Fixup signal voltage switch

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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: Johan Rudholm <johan.rudholm@stericsson.com>
Signed-off-by: Kevin Liu <kliu5@marvell.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Wei WANG <wei_wang@realsil.com.cn>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Johan Rudholm 2013-01-28 15:08:28 +01:00 committed by Chris Ball
parent 567c89032c
commit 0797e5f145
3 changed files with 107 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

83
drivers/mmc/core/core.c
View file

@ -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);
@ -1347,20 +1348,82 @@ 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) {
cmd.opcode = SD_SWITCH_VOLTAGE;
cmd.arg = 0;
cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
if (signal_voltage == MMC_SIGNAL_VOLTAGE_330)
return __mmc_set_signal_voltage(host, signal_voltage);
err = mmc_wait_for_cmd(host, &cmd, 0);
if (err)
return err;
/*
* 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));
if (!mmc_host_is_spi(host) && (cmd.resp[0] & R1_ERROR))
return -EIO;
cmd.opcode = SD_SWITCH_VOLTAGE;
cmd.arg = 0;
cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
err = mmc_wait_for_cmd(host, &cmd, 0);
if (err)
return err;
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);
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;
}
return __mmc_set_signal_voltage(host, signal_voltage);
/* 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;
}
/*

21
drivers/mmc/core/sd.c
View file

@ -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;
}
}

20
drivers/mmc/core/sdio.c
View file

@ -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;
}