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| author | Lucas Stach <l.stach@pengutronix.de> | 2018-07-25 11:57:28 +0200 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2018-08-09 08:19:50 +0200 |
| commit | 77f3378135f15c1c5c7e091731b6375d6d8ff423 (patch) | |
| tree | e43094dc5d9a4366f6456239567eb05bdb0acd97 /drivers/mci | |
| parent | 107ac101928f6b28ec69b02dd76861a175501865 (diff) | |
| download | barebox-77f3378135f15c1c5c7e091731b6375d6d8ff423.tar.gz barebox-77f3378135f15c1c5c7e091731b6375d6d8ff423.tar.xz | |
mci: imx-esdhc: send required clock pulses to card on init
MMC cards need at least 74 clock pulses before any bus communication
can occur. The i.MX SDHC controller auto-gates the clock when inactive,
so if the SD enumeration is skipped for slots where we know that only a
MMC card can be present (which is possible since
b5289b742a89 "mmc: allow skipping SD card initialization") those
inititialization clock pulses won't be sent out, resulting in command
timeouts when trying to enumerate the card.
Luckily the eSDHC controller has a hardware feature to send out 80
clock pulses. This has been validated to be available by checking the
reference manual back to i.MX25.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'drivers/mci')
| -rw-r--r-- | drivers/mci/imx-esdhc.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/mci/imx-esdhc.c b/drivers/mci/imx-esdhc.c index c4daa9d121..db96a81397 100644 --- a/drivers/mci/imx-esdhc.c +++ b/drivers/mci/imx-esdhc.c @@ -455,10 +455,13 @@ static void set_sysctl(struct mci_host *mci, u32 clock) wait_on_timeout(10 * MSECOND, esdhc_read32(regs + SDHCI_PRESENT_STATE) & PRSSTAT_SDSTB); - clk = SYSCTL_PEREN | SYSCTL_CKEN; + clk = SYSCTL_PEREN | SYSCTL_CKEN | SYSCTL_INITA; esdhc_setbits32(regs + SDHCI_CLOCK_CONTROL__TIMEOUT_CONTROL__SOFTWARE_RESET, clk); + + wait_on_timeout(1 * MSECOND, + !(esdhc_read32(regs + SDHCI_CLOCK_CONTROL) & SYSCTL_INITA)); } static void esdhc_set_ios(struct mci_host *mci, struct mci_ios *ios) |