From: Haibo Chen haibo.chen@nxp.com

After commit f132aab40327 ("Revert "mmc: fsl_esdhc_imx: use VENDORSPEC_FRC_SDCLK_ON to control card clock output""), it involve issue in mmc_switch_voltage(), because of the special design of usdhc.

For FSL_USDHC, it do not implement VENDORSPEC_CKEN/PEREN/HCKEN/IPGEN, these are reserved bits(Though RM contain the definition of these bits, but actually internal IC logic do not implement, already confirm with IC team). Instead, use VENDORSPEC_FRC_SDCLK_ON to gate on/off the card clock output. Here is the definition of this bit in RM:

[8] FRC_SDCLK_ON Force CLK output active Do not set this bit to 1 unless it is necessary. Also, make sure that this bit is cleared when uSDHC’s clock is about to be changed (frequency change, clock source change, or delay chain tuning). 0b - CLK active or inactive is fully controlled by the hardware. 1b - Force CLK active

In default, the FRC_SDCLK_ON is 0. This means, when there is no command or data transfer on bus, hardware will gate off the card clock. But in some case, we need the card clock keep on. Take IO voltage 1.8v switch as example, after IO voltage change to 1.8v, spec require gate off the card clock for 5ms, and gate on the clock back, once detect the card clock on, then the card will draw the dat0 to high immediately. If there is not clock gate off/on behavior, some card will keep the dat0 to low level. This is the reason we fail in mmc_switch_voltage().

To fix this issue, and concern that this is only the fsl usdhc hardware design limitation, set the bit FRC_SDCLK_ON in the beginning of the wait_dat0() and clear it in the end. To make sure the 1.8v IO voltage switch process align with SD specification.

For standard tuning process, usdhc specification also require the card clock keep on, so also add these behavior in fsl_esdhc_execute_tuning().

Signed-off-by: Haibo Chen haibo.chen@nxp.com --- drivers/mmc/fsl_esdhc_imx.c | 19 ++++++++++++++++++- include/fsl_esdhc_imx.h | 2 ++ 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c index 9299635f50..362e3e13b6 100644 --- a/drivers/mmc/fsl_esdhc_imx.c +++ b/drivers/mmc/fsl_esdhc_imx.c @@ -832,12 +832,15 @@ static int fsl_esdhc_execute_tuning(struct udevice *dev, uint32_t opcode) u32 irqstaten = esdhc_read32(&regs->irqstaten); u32 irqsigen = esdhc_read32(&regs->irqsigen); int i, ret = -ETIMEDOUT; - u32 val, mixctrl; + u32 val, mixctrl, tmp;

/* clock tuning is not needed for upto 52MHz */ if (mmc->clock <= 52000000) return 0;

+ /* make sure the card clock keep on */ + esdhc_setbits32(&regs->vendorspec, VENDORSPEC_FRC_SDCLK_ON); + /* This is readw/writew SDHCI_HOST_CONTROL2 when tuning */ if (priv->flags & ESDHC_FLAG_STD_TUNING) { val = esdhc_read32(&regs->autoc12err); @@ -897,6 +900,11 @@ static int fsl_esdhc_execute_tuning(struct udevice *dev, uint32_t opcode)

esdhc_stop_tuning(mmc);

+ /* change to default setting, let host control the card clock */ + esdhc_clrbits32(&regs->vendorspec, VENDORSPEC_FRC_SDCLK_ON); + if (readx_poll_timeout(esdhc_read32, &regs->prsstat, tmp, tmp & PRSSTAT_SDOFF, 100)) + pr_warn("fsl_esdhc_imx: card clock not gate off as expect.\n"); + return ret; } #endif @@ -1560,9 +1568,18 @@ static int fsl_esdhc_wait_dat0(struct udevice *dev, int state, struct fsl_esdhc_priv *priv = dev_get_priv(dev); struct fsl_esdhc *regs = priv->esdhc_regs;

+ /* make sure the card clock keep on */ + esdhc_setbits32(&regs->vendorspec, VENDORSPEC_FRC_SDCLK_ON); + ret = readx_poll_timeout(esdhc_read32, &regs->prsstat, tmp, !!(tmp & PRSSTAT_DAT0) == !!state, timeout_us); + + /* change to default setting, let host control the card clock */ + esdhc_clrbits32(&regs->vendorspec, VENDORSPEC_FRC_SDCLK_ON); + if (readx_poll_timeout(esdhc_read32, &regs->prsstat, tmp, tmp & PRSSTAT_SDOFF, 100)) + pr_warn("fsl_esdhc_imx: card clock not gate off as expect.\n"); + return ret; }

diff --git a/include/fsl_esdhc_imx.h b/include/fsl_esdhc_imx.h index 2153f29bef..b8efd2a166 100644 --- a/include/fsl_esdhc_imx.h +++ b/include/fsl_esdhc_imx.h @@ -37,6 +37,7 @@ #define VENDORSPEC_HCKEN 0x00001000 #define VENDORSPEC_IPGEN 0x00000800 #define VENDORSPEC_INIT 0x20007809 +#define VENDORSPEC_FRC_SDCLK_ON 0x00000100

#define IRQSTAT 0x0002e030 #define IRQSTAT_DMAE (0x10000000) @@ -94,6 +95,7 @@ #define PRSSTAT_CINS (0x00010000) #define PRSSTAT_BREN (0x00000800) #define PRSSTAT_BWEN (0x00000400) +#define PRSSTAT_SDOFF (0x00000080) #define PRSSTAT_SDSTB (0X00000008) #define PRSSTAT_DLA (0x00000004) #define PRSSTAT_CICHB (0x00000002)