* [PATCH] mmc: sdhci: wait 5ms after set 1.8V signal enable
@ 2017-12-13 23:41 Zhoujie Wu
0 siblings, 0 replies; only message in thread
From: Zhoujie Wu @ 2017-12-13 23:41 UTC (permalink / raw)
To: ulf.hansson, adrian.hunter, linux-mmc
Cc: zmxu, jszhang, nadavh, xigu, xswang, dingwei, kostap, hannah,
hongd, dougj, ygao, liuw, gregory.clement, thomas.petazzoni,
Zhoujie Wu
According to SD spec 3.00 3.6.1 signal voltage switch
procedure, 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.
On some cards, found without the delay would see "1.8V
regulator output did not became stable" err log.
Signed-off-by: Zhoujie Wu <zjwu@marvell.com>
---
drivers/mmc/host/sdhci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index e9290a3..fe5f208 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1933,6 +1933,9 @@ int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
if (host->ops->voltage_switch)
host->ops->voltage_switch(host);
+ /* Wait for 5ms */
+ usleep_range(5000, 5500);
+
/* 1.8V regulator output should be stable within 5 ms */
ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
if (ctrl & SDHCI_CTRL_VDD_180)
--
1.9.1
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2017-12-13 23:41 [PATCH] mmc: sdhci: wait 5ms after set 1.8V signal enable Zhoujie Wu
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