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authorUlf Hansson <ulf.hansson@linaro.org>2013-09-16 11:28:42 +0200
committerChris Ball <cjb@laptop.org>2013-10-30 20:26:30 -0400
commitce69d37b7d8fa692c45d71d94aa0c921859b82ce (patch)
treeaef1e93b62424f07b72ddd322a64e6435b27d932 /drivers/mmc/core
parent6904115095ad60ced638eb1e36e0e4e5e7de00b0 (diff)
mmc: core: Prevent violation of specs while initializing cards
According to eMMC/SD/SDIO specs, the VDD (VCC) voltage level must be maintained during the initialization sequence. If we want/need to tune the voltage level, a complete power cycle of the card must be executed. Most host drivers conforms to the specifications by only allowing to change VDD voltage level at the MMC_POWER_UP state, but some also cares about MMC_POWER_ON state, which they should'nt. This patch will not break those drivers, but they could clean up code to better reflect what is expected from the protocol layer. A big re-work of the mmc_select_voltage function is done to only change VDD voltage level if the host supports MMC_CAP2_FULL_PWR_CYCLE. Otherwise only validation of the host and card ocr mask will be done. A very nice side-effect of this patch is that we now don't need to reset the negotiated ocr mask at the mmc_power_off function, since now it will actually reflect the present voltage level, which safely can be used at the next power up and re-initialization. Moreover, we then only need to execute mmc_select_voltage from the attach sequence. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc/core')
-rw-r--r--drivers/mmc/core/core.c31
-rw-r--r--drivers/mmc/core/mmc.c1
-rw-r--r--drivers/mmc/core/sd.c1
-rw-r--r--drivers/mmc/core/sdio.c17
4 files changed, 13 insertions, 37 deletions
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 529d2eff609..63672aba0e9 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1358,21 +1358,20 @@ u32 mmc_select_voltage(struct mmc_host *host, u32 ocr)
int bit;
ocr &= host->ocr_avail;
+ if (!ocr) {
+ dev_warn(mmc_dev(host), "no support for card's volts\n");
+ return 0;
+ }
- bit = ffs(ocr);
- if (bit) {
- bit -= 1;
-
+ if (host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) {
+ bit = ffs(ocr) - 1;
ocr &= 3 << bit;
-
- mmc_host_clk_hold(host);
- host->ios.vdd = bit;
- mmc_set_ios(host);
- mmc_host_clk_release(host);
+ mmc_power_cycle(host, ocr);
} else {
- pr_warning("%s: host doesn't support card's voltages\n",
- mmc_hostname(host));
- ocr = 0;
+ bit = fls(ocr) - 1;
+ ocr &= 3 << bit;
+ if (bit != host->ios.vdd)
+ dev_warn(mmc_dev(host), "exceeding card's volts\n");
}
return ocr;
@@ -1571,14 +1570,6 @@ void mmc_power_off(struct mmc_host *host)
host->ios.clock = 0;
host->ios.vdd = 0;
-
- /*
- * Reset ocr mask to be the highest possible voltage supported for
- * this card. This value will be used at next power up.
- */
- if (host->card)
- host->card->ocr = 1 << (fls(host->ocr_avail) - 1);
-
if (!mmc_host_is_spi(host)) {
host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
host->ios.chip_select = MMC_CS_DONTCARE;
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index eb7161c1158..18ce81a85c9 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1535,7 +1535,6 @@ static int mmc_resume(struct mmc_host *host)
mmc_claim_host(host);
mmc_power_up(host, host->card->ocr);
- mmc_select_voltage(host, host->card->ocr);
err = mmc_init_card(host, host->card->ocr, host->card);
mmc_release_host(host);
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 398065c57ed..53db60a76da 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1103,7 +1103,6 @@ static int mmc_sd_resume(struct mmc_host *host)
mmc_claim_host(host);
mmc_power_up(host, host->card->ocr);
- mmc_select_voltage(host, host->card->ocr);
err = mmc_sd_init_card(host, host->card->ocr, host->card);
mmc_release_host(host);
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index e0a135a635f..b7c19e894dd 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -987,7 +987,6 @@ static int mmc_sdio_resume(struct mmc_host *host)
/* Restore power if needed */
if (!mmc_card_keep_power(host)) {
mmc_power_up(host, host->card->ocr);
- mmc_select_voltage(host, host->card->ocr);
/*
* Tell runtime PM core we just powered up the card,
* since it still believes the card is powered off.
@@ -1045,7 +1044,6 @@ static int mmc_sdio_resume(struct mmc_host *host)
static int mmc_sdio_power_restore(struct mmc_host *host)
{
int ret;
- u32 ocr, rocr;
BUG_ON(!host);
BUG_ON(!host->card);
@@ -1067,28 +1065,17 @@ static int mmc_sdio_power_restore(struct mmc_host *host)
* for OLPC SD8686 (which expects a [CMD5,5,3,7] init sequence), and
* harmless in other situations.
*
- * With these steps taken, mmc_select_voltage() is also required to
- * restore the correct voltage setting of the card.
*/
sdio_reset(host);
mmc_go_idle(host);
mmc_send_if_cond(host, host->ocr_avail);
- ret = mmc_send_io_op_cond(host, 0, &ocr);
+ ret = mmc_send_io_op_cond(host, 0, NULL);
if (ret)
goto out;
- if (host->ocr_avail_sdio)
- host->ocr_avail = host->ocr_avail_sdio;
-
- rocr = mmc_select_voltage(host, ocr & ~0x7F);
- if (!rocr) {
- ret = -EINVAL;
- goto out;
- }
-
- ret = mmc_sdio_init_card(host, rocr, host->card,
+ ret = mmc_sdio_init_card(host, host->card->ocr, host->card,
mmc_card_keep_power(host));
if (!ret && host->sdio_irqs)
mmc_signal_sdio_irq(host);