On 12/7/2012 9:49 PM, Johan Rudholm wrote:
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 if these requirements are not fulfilled, the 1.8V signal voltage switch may not be successful. Signed-off-by: Johan Rudholm <johan.rudh...@stericsson.com> --- drivers/mmc/core/core.c | 35 +++++++++++++++++++++++++++++++++++ drivers/mmc/core/sd.c | 26 +++++++++++++++++++++----- drivers/mmc/core/sdio.c | 25 +++++++++++++++++++++++-- 3 files changed, 79 insertions(+), 7 deletions(-) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 285f064..c9a7a8a 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -1246,8 +1246,43 @@ int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage, bool cmd11 host->ios.signal_voltage = signal_voltage;if (host->ops->start_signal_voltage_switch) {+ u32 clock; + mmc_host_clk_hold(host); + /* + * During a signal voltage level switch, the clock must be gated + * for a certain period of time according to the SD spec + */ + if (cmd11) { + clock = host->ios.clock; + host->ios.clock = 0; + mmc_set_ios(host); + } + err = host->ops->start_signal_voltage_switch(host, &host->ios);
Shouldn't you fix all the existing host drivers who have already implemented start_signal_voltage_switch host ops? If you don't change them as part of this patch then i afraid UHS functionality would be broken on those platforms. Also, it's not just changing the start_signal_voltage_switch hot op implementation, you may also need to add card_busy() host op implementation for those drivers.
+ + if (err && cmd11) { + host->ios.clock = clock; + mmc_set_ios(host); + } else if (cmd11) { + /* 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) + pr_warning("%s: cannot verify signal voltage switch\n", + mmc_hostname(host)); + else if (host->ops->card_busy(host)) + err = -EAGAIN; + } mmc_host_clk_release(host); }diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.cindex 74972c2..eb299bc 100644 --- a/drivers/mmc/core/sd.c +++ b/drivers/mmc/core/sd.c @@ -713,6 +713,14 @@ 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 @@ -734,9 +742,10 @@ 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 (host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | + if (retries && host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50)) ocr |= SD_OCR_S18R;@@ -748,7 +757,6 @@ 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; @@ -760,8 +768,16 @@ try_again: if (!mmc_host_is_spi(host) && rocr && ((*rocr & 0x41000000) == 0x41000000)) { err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180, true); - if (err) { - ocr &= ~SD_OCR_S18R; + if (err == -EAGAIN) { + /* Power cycle card */ + pr_debug("%s: Signal voltage switch failed, " + "power cycling card (retries = %d)\n", + mmc_hostname(host), retries); + mmc_power_cycle(host); + 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 2273ce6..573ab06 100644 --- a/drivers/mmc/core/sdio.c +++ b/drivers/mmc/core/sdio.c @@ -583,10 +583,19 @@ 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 */ @@ -645,14 +654,26 @@ 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) && + if (!powered_resume && (ocr & R4_18V_PRESENT) && (host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) { err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180, true); - if (err) { + if (err == -EAGAIN) { + /* Power cycle card */ + pr_debug("%s: Signal voltage switch failed, " + "power cycling card (retries = %d)\n", + mmc_hostname(host), retries); + mmc_power_cycle(host); + 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; }
-- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
