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@xxxxxxxxxxxxxx>
Signed-off-by: Kevin Liu <kliu5@xxxxxxxxxxx>
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Tested-by: Wei WANG <wei_wang@xxxxxxxxxxxxxx>
---
drivers/mmc/core/core.c | 83 +++++++++++++++++++++++++++++++++++++++++------
drivers/mmc/core/sd.c | 21 +++++++++---
drivers/mmc/core/sdio.c | 20 ++++++++++--
3 files changed, 107 insertions(+), 17 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 3823351..2aee757 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -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));
+
+ 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;
+ 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;
}
/*
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 9a59fcd..03134b1 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -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 @@ try_again:
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;
}
}
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 1a726ae..aa0719a 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -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;
}
--
1.7.10
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