Hi,
On Thu, Jul 26 2012, Seungwon Jeon wrote:
> July 26, 2012, 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.
>>
>> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
>> ---
>> Changes in v4:
>> - Don't regenerate slot variable when we already had it.
>>
>> Changes in v3:
>> - Commenting fixes requested by Seungwoon Jeon and Jaehoon Chung.
>> - Only pass 'slot' to the low power disable function since whole mmc
>> structure wasn't needed.
>>
>> Changes in v2:
>> - Commenting fixes requested by Grant Grundler.
>> - Be extra certain that we don't re-turn on the low power mode in
>> CLKENA in dw_mci_setup_bus() if SDIO interrupts are enabled.
>> There are no known instances of this happening but it's good to be safe.
>>
>> drivers/mmc/host/dw_mmc.c | 41 ++++++++++++++++++++++++++++++++++++++---
>> 1 files changed, 38 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 72dc3cd..882748b 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -627,6 +627,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>> {
>> struct dw_mci *host = slot->host;
>> u32 div;
>> + u32 clk_en_a;
>>
>> if (slot->clock != host->current_speed) {
>> div = host->bus_hz / slot->clock;
>> @@ -659,9 +660,11 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>> mci_send_cmd(slot,
>> SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
>>
>> - /* enable clock */
>> - mci_writel(host, CLKENA, ((SDMMC_CLKEN_ENABLE |
>> - SDMMC_CLKEN_LOW_PWR) << slot->id));
>> + /* enable clock; only low power if no SDIO */
>> + clk_en_a = SDMMC_CLKEN_ENABLE << slot->id;
>> + if (!(mci_readl(host, INTMASK) & SDMMC_INT_SDIO(slot->id)))
>> + clk_en_a |= SDMMC_CLKEN_LOW_PWR << slot->id;
>> + mci_writel(host, CLKENA, clk_en_a);
>>
>> /* inform CIU */
>> mci_send_cmd(slot,
>> @@ -862,6 +865,30 @@ 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 the
>> + * description of the CLKENA register we should disable low power mode
>> + * for SDIO cards if we need SDIO interrupts to work.
>> + *
>> + * This function is fast if low power mode is already disabled.
>> + */
>> +static void dw_mci_disable_low_power(struct dw_mci_slot *slot)
>> +{
>> + 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 +898,14 @@ 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 low power mode disabled and it will get
>> + * re-enabled again in dw_mci_setup_bus().
>> + */
>> + dw_mci_disable_low_power(slot);
>> +
>> mci_writel(host, INTMASK,
>> (int_mask | SDMMC_INT_SDIO(slot->id)));
>> } else {
>
> Basically, disabling low power mode doesn't affect origin working.
> This patch will guarantees to supply the clock while sdio interrupt is activated.
> Looks good to me.
> Chris, feel free to add my ack.
>
> Acked-by: Seungwon Jeon <tgih.jun@xxxxxxxxxxx>
Thanks, pushed to mmc-next for 3.7.
- Chris.
--
Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/>
One Laptop Per Child
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