Hi, Le 01/03/2017 à 10:53, Arend Van Spriel a écrit : > On 1-3-2017 9:59, Romain Perier wrote: >> Currently, mmc_power_up calls the pre_power_on callback, enables the >> power supply of the mmc by calling mmc_set_ios() and then call >> post_power_on. WiFi chipsets like the AP6335 require a specific power >> sequence ordering before being used. You must enable the power supply >> and wait until it reaches its minimum voltage, gate the clock and wait >> at least two cycles and then assert the reset line. > Hi Romain, > > You have to be more clear. What power supply, ie. vmmc or the supply for > the wifi chipset. Without knowing much of the details to me this sounds > like a new powerseq variant. That's for vqmmc. vqmmc has to be power on, then the clock must be enabled and then the reset line must be toggled. > >> This commit prevents regulators to be enabled in the middle of or after >> the power sequencing. We this fix, mmc_set_ios is first call, the >> underlying regulators are enabled, then pre_power_on and post_power_on >> are called, so clock and reset line are enabled in the right order, >> after the regulator. > It feels counter intuitive and maybe even wrong to change a setup > pattern like this. Can you be sure this will not cause any regressions? Well, I could keep the current pattern as it was currently working, and propose another one for this case (as an RFC). What do you think ? Regards, Romain > > Regards, > Arend > >> Signed-off-by: Romain Perier <romain.perier@xxxxxxxxxxxxx> >> --- >> drivers/mmc/core/core.c | 13 +++++++++---- >> 1 file changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c >> index 1076b9d..36df24f 100644 >> --- a/drivers/mmc/core/core.c >> +++ b/drivers/mmc/core/core.c >> @@ -1798,8 +1798,6 @@ void mmc_power_up(struct mmc_host *host, u32 ocr) >> if (host->ios.power_mode == MMC_POWER_ON) >> return; >> >> - mmc_pwrseq_pre_power_on(host); >> - >> host->ios.vdd = fls(ocr) - 1; >> host->ios.power_mode = MMC_POWER_UP; >> /* Set initial state and call mmc_set_ios */ >> @@ -1819,13 +1817,20 @@ void mmc_power_up(struct mmc_host *host, u32 ocr) >> */ >> mmc_delay(10); >> >> - mmc_pwrseq_post_power_on(host); >> - >> host->ios.clock = host->f_init; >> >> host->ios.power_mode = MMC_POWER_ON; >> mmc_set_ios(host); >> >> + mmc_pwrseq_pre_power_on(host); >> + >> + /* >> + * This delay should be sufficient to wait at least two cycles of clock >> + * gated by pre_power_on >> + */ >> + mmc_delay(1); >> + mmc_pwrseq_post_power_on(host); >> + >> /* >> * This delay must be at least 74 clock sizes, or 1 ms, or the >> * time required to reach a stable voltage. >> -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
