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: 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>
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 @@
{
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 @@
* 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;
}