On Fri, Jul 20, 2012 at 7:13 PM, Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
> The documentation for the dw_mmc part says that the low power
> mode should normally only be set for MMC and SD memory and should
> be turned off for SDIO cards that need interrupts detected.
>
> The best place I could find to do this is when the SDIO interrupt
> was first enabled. I rely on the fact that dw_mci_setup_bus()
> will be called when it's time to reenable.
>
> Change-Id: Id0e33a4e3a0a77ce8a5053b6e73197d53a5d46bb
> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
> ---
> drivers/mmc/host/dw_mmc.c | 33 +++++++++++++++++++++++++++++++++
> 1 files changed, 33 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 72dc3cd..0cb2756 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -862,6 +862,31 @@ static int dw_mci_get_cd(struct mmc_host *mmc)
> return present;
> }
>
> +/*
> + * Disable lower power mode.
> + *
> + * Low power mode will stop the card clock when idle. According to
> + * documentation we should disable low power mode for SDIO cards if we
> + * need interrupts to work.
> + *
> + * This function is fast if the power mode is already disabled.
> + */
> +static void dw_mci_disable_low_power(struct mmc_host *mmc)
> +{
> + struct dw_mci_slot *slot = mmc_priv(mmc);
> + struct dw_mci *host = slot->host;
> + u32 clk_en_a;
> + const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id;
> +
> + clk_en_a = mci_readl(host, CLKENA);
> +
> + if (clk_en_a & clken_low_pwr) {
> + mci_writel(host, CLKENA, clk_en_a & ~clken_low_pwr);
> + mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
> + SDMMC_CMD_PRV_DAT_WAIT, 0);
> + }
> +}
> +
> static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
> {
> struct dw_mci_slot *slot = mmc_priv(mmc);
> @@ -871,6 +896,14 @@ static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
> /* Enable/disable Slot Specific SDIO interrupt */
> int_mask = mci_readl(host, INTMASK);
> if (enb) {
> + /*
> + * Turn off low power mode if it was enabled. This is a bit of
> + * a heavy operation and we disable / enable IRQs a lot, so
> + * we'll leave them disabled; they will get re-enabled again in
> + * dw_mci_setup_bus().
> + */
> + dw_mci_disable_low_power(mmc);
> +
> mci_writel(host, INTMASK,
> (int_mask | SDMMC_INT_SDIO(slot->id)));
> } else {
> --
> 1.7.7.3
Is it safe to just disable low power here or could the setting be
overwritten in setup_bus?
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