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Date: Fri, 18 Oct 2013 18:42:11 +0900
From: Jaehoon Chung <jh80.chung@...sung.com>
To: Doug Anderson <dianders@...omium.org>, Chris Ball <cjb@...top.org>
Cc: Seungwon Jeon <tgih.jun@...sung.com>,
James Hogan <james.hogan@...tec.com>,
Grant Grundler <grundler@...omium.org>,
Alim Akhtar <alim.akhtar@...sung.com>,
Abhilash Kesavan <a.kesavan@...sung.com>,
Tomasz Figa <tomasz.figa@...il.com>,
Olof Johansson <olof@...om.net>,
Sonny Rao <sonnyrao@...omium.org>,
Bing Zhao <bzhao@...vell.com>, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mmc: dw_mmc: Cleanup disable of low power mode w/ SDIO
interrupts
Hi Doug,
On 10/16/2013 07:39 AM, Doug Anderson wrote:
> In the patch (9623b5b mmc: dw_mmc: Disable low power mode if SDIO
> interrupts are used) I added code that disabled the low power mode of
> dw_mmc when SDIO interrupts are used. That code worked but always
> felt a little hacky because we ended up disabling low power as a side
> effect of the first enable_sdio_irq() call. That wouldn't be so bad
> except that disabling low power involves a complicated process of
> writing to the CMD/CMDARG registers and that extra process makes it
> difficult to cleanly the read-modify-write race in
> dw_mci_enable_sdio_irq() (see future patch in the series).
>
> Change the code to take advantage of the init_card() callback of the
> mmc core to know when an SDIO card has been inserted. If we've got a
> SDIO card and we're configured to use SDIO Interrupts then turn off
> "low power mode" right away.
>
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> ---
> drivers/mmc/host/dw_mmc.c | 68 ++++++++++++++++++++++++-----------------------
> drivers/mmc/host/dw_mmc.h | 1 +
> 2 files changed, 36 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 0a6a512..1b75816 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -27,6 +27,7 @@
> #include <linux/stat.h>
> #include <linux/delay.h>
> #include <linux/irq.h>
> +#include <linux/mmc/card.h>
> #include <linux/mmc/host.h>
> #include <linux/mmc/mmc.h>
> #include <linux/mmc/sdio.h>
> @@ -822,7 +823,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
>
> /* 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)))
> + if (!test_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags))
> clk_en_a |= SDMMC_CLKEN_LOW_PWR << slot->id;
> mci_writel(host, CLKENA, clk_en_a);
>
> @@ -1050,27 +1051,37 @@ 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)
> +static void dw_mci_init_card(struct mmc_host *mmc, struct mmc_card *card)
> {
> + 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);
> + /*
> + * 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.
> + */
> + if (mmc->caps | MMC_CAP_SDIO_IRQ) {
mmc->caps & MMC_CAP_SDIO_IRQ?
> + const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id;
> + u32 clk_en_a_old;
> + u32 clk_en_a;
>
> - 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);
> + clk_en_a_old = mci_readl(host, CLKENA);
> +
> + if (card->type == MMC_TYPE_SDIO ||
> + card->type == MMC_TYPE_SD_COMBO) {
> + set_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags);
> + clk_en_a = clk_en_a_old & ~clken_low_pwr;
> + } else {
> + clear_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags);
> + clk_en_a = clk_en_a_old | clken_low_pwr;
When this condition is entered? card->type is always MMC_TYPE_SDIO or MMC_TYPE_SD_COMBO, isn't?
Best Regards,
Jaehoon Chung
> + }
> +
> + if (clk_en_a != clk_en_a_old) {
> + mci_writel(host, CLKENA, clk_en_a);
> + mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
> + SDMMC_CMD_PRV_DAT_WAIT, 0);
> + }
> }
> }
>
> @@ -1082,21 +1093,11 @@ 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 {
> - mci_writel(host, INTMASK,
> - (int_mask & ~SDMMC_INT_SDIO(slot->id)));
> - }
> + if (enb)
> + int_mask |= SDMMC_INT_SDIO(slot->id);
> + else
> + int_mask &= ~SDMMC_INT_SDIO(slot->id);
> + mci_writel(host, INTMASK, int_mask);
> }
>
> static int dw_mci_execute_tuning(struct mmc_host *mmc, u32 opcode)
> @@ -1140,6 +1141,7 @@ static const struct mmc_host_ops dw_mci_ops = {
> .get_cd = dw_mci_get_cd,
> .enable_sdio_irq = dw_mci_enable_sdio_irq,
> .execute_tuning = dw_mci_execute_tuning,
> + .init_card = dw_mci_init_card,
> };
>
> static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
> index 6bf24ab..26d4657 100644
> --- a/drivers/mmc/host/dw_mmc.h
> +++ b/drivers/mmc/host/dw_mmc.h
> @@ -227,6 +227,7 @@ struct dw_mci_slot {
> unsigned long flags;
> #define DW_MMC_CARD_PRESENT 0
> #define DW_MMC_CARD_NEED_INIT 1
> +#define DW_MMC_CARD_NO_LOW_PWR 2
> int id;
> int last_detect_state;
> };
>
--
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