Hi Wenyou,
> On Sep 16, 2015, at 11:22 , Wenyou Yang <wenyou.y...@atmel.com> wrote:
>
> According to the SDHC specification, stopping the SD Clock is by setting
> the SD Clock Enable bit in the Clock Control register at 0, instead of
> setting all bits at 0.
>
> Before stopping the SD clock, we need to make sure all SD transactions
> to complete, so add checking the CMD and DAT bits in the Presen State
> register, before stopping the SD clock.
>
> Signed-off-by: Wenyou Yang <wenyou.y...@atmel.com>
> ---
>
> drivers/mmc/sdhci.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
> index d89e302..f02db4e 100644
> --- a/drivers/mmc/sdhci.c
> +++ b/drivers/mmc/sdhci.c
> @@ -286,9 +286,15 @@ static int sdhci_send_command(struct mmc *mmc, struct
> mmc_cmd *cmd,
> static int sdhci_set_clock(struct mmc *mmc, unsigned int clock)
> {
> struct sdhci_host *host = mmc->priv;
> - unsigned int div, clk, timeout;
> + unsigned int div, clk, timeout, reg;
>
> - sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> + while (sdhci_readl(host, SDHCI_PRESENT_STATE) &
> + (SDHCI_CMD_INHIBIT | SDHCI_DATA_INHIBIT))
> + ;
> +
Put a timeout here in case something is broken.
> + reg = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> + reg &= ~SDHCI_CLOCK_CARD_EN;
> + sdhci_writew(host, reg, SDHCI_CLOCK_CONTROL);
>
> if (clock == 0)
> return 0;
> --
> 1.7.9.5
>
Regards
— Pantelis
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