From: Zhoujie Wu zjwu@marvell.com
[ Upstream commit 8d876bf472dba73c015cea9feea80dcb80626a7c ]
According to SD spec 3.00 3.6.1 signal voltage switch procedure step 6~8, (6) Set 1.8V Signal Enable in the Host Control 2 register. (7) Wait 5ms. 1.8V voltage regulator shall be stable within this period. (8) If 1.8V Signal Enable is cleared by Host Controller, go to step (12). Host should wait 5ms after set 1.8V signal enable bit in Host Control 2 register and check if 1.8V is stable or not.
But current code checks this bit right after set it. On some platforms with xenon controller found the bit is cleared right away and host reports "1.8V regulator output did not became stable" and 5ms delay can help.
Implement voltage_switch callback for xenon controller to add 5ms delay to make sure the 1.8V signal enable bit is set by controller.
Signed-off-by: Zhoujie Wu zjwu@marvell.com Acked-by: Adrian Hunter adrian.hunter@intel.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/mmc/host/sdhci-xenon.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/mmc/host/sdhci-xenon.c b/drivers/mmc/host/sdhci-xenon.c index 0842bbc2d7ad..4d0791f6ec23 100644 --- a/drivers/mmc/host/sdhci-xenon.c +++ b/drivers/mmc/host/sdhci-xenon.c @@ -230,7 +230,14 @@ static void xenon_set_power(struct sdhci_host *host, unsigned char mode, mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd); }
+static void xenon_voltage_switch(struct sdhci_host *host) +{ + /* Wait for 5ms after set 1.8V signal enable bit */ + usleep_range(5000, 5500); +} + static const struct sdhci_ops sdhci_xenon_ops = { + .voltage_switch = xenon_voltage_switch, .set_clock = sdhci_set_clock, .set_power = xenon_set_power, .set_bus_width = sdhci_set_bus_width,