From ce69d37b7d8fa692c45d71d94aa0c921859b82ce Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Mon, 16 Sep 2013 11:28:42 +0200 Subject: 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 Signed-off-by: Chris Ball --- drivers/mmc/core/core.c | 31 +++++++++++-------------------- drivers/mmc/core/mmc.c | 1 - drivers/mmc/core/sd.c | 1 - drivers/mmc/core/sdio.c | 17 ++--------------- 4 files changed, 13 insertions(+), 37 deletions(-) (limited to 'drivers/mmc/core') 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); -- cgit v1.2.3