Messages in this thread | | | Subject | Re: [PATCH v2] mmc: dw_mmc: add hw_reset support | From | Shawn Lin <> | Date | Mon, 4 Jan 2016 15:24:09 +0800 |
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On 2016/1/4 13:52, Jaehoon Chung wrote: > Hi, Shawn. > > On 01/04/2016 11:50 AM, Shawn Lin wrote: >> This patch implement hw_reset function for DesignWare >> MMC controller. By adding this feature, mmc blk can >> do some basic recovery. >> >> >From Synopsys DesignWare Cores Mobile Storage Host Databook >> (Section 7.4.4), we get the details: >> 1. Program CMD12 to end any transfer in process. >> 2. Wait for DTO, even if no response is sent back by the card. >> 3. Set the following resets: >> Software reset – BMOD[0] for IDMAC only >> DMA reset– CTRL[2] >> FIFO reset – CTRL[1] bits >> 4. Program the CARD_RESET register with a value of 0 for the bit >> corresponding to the card number; This can be done at any time when >> the card is connected to the controller. This programming asserts the >> RST_n signal and resets the card. >> 5. Wait for minimum of 1 μs or cclk_in period, which ever is greater >> 6. After a minimum of 1 μs, the application should program a value of >> 0 into the CARD_RESET register for the bit corresponding to the card >> number. This de-asserts the RST_n signal and takes the card out of reset. >> 7. The application can program a new CMD only after a minimum of 200 us >> after the de-assertion of the RST_n signal, as per the MMC 4.41 standard. >> >> HW reset producer will be call in mmc_init_card before mmc_go_idle. At that >> time,dw mmc hasn't update clk for itself, so CMD12 is inappropriate and >> unnecessary. Moreover, if mmc device runs into broken states, DRTO or RTO >> generated by previous cmd w/ data will make mmc core issue stop already. Then >> it will retry again and again, issue stop and card status again until the >> cmd's retry number decrease to zero. That will finally trigger HW reset producer >> if we declare MMC_CAP_HW_RESET. So there's no need to do step 1 and 2 for the >> reasons we mentioned above. > > Which IP version did you use? Could you share it..? > Did you know about CHIP RESET sequence? >
My dw_mmc IP version is 270a(0x5342270a from VERID register). Do you mean "emmc chip hardware reset sequence"? From JESD84-B51 spec(section 6.15.10),
host pull down reset pin for at least 1us, and pull high it. then emmc device will detect it as a IO interrupt to enter internal reset flow. Host should not issue CMD1 within 200us, which means emmc device MUST finish internal reset flow within 200us.
>> >> This implementation can be easily tested by cutting off->On vmmc while doing data >> accessing in background to simulate that case. And dw_mmc can generate timeout >> interrupt and make mmc core trigger hw reset producer before re-init mmc card >> to recover itself. >> >> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> >> >> --- >> >> Changes in v2: >> - remove unecessary mb >> - reduce time cost for hw_reset >> - combine SDMMC_CTRL_DMA_RESET and SDMMC_CTRL_FIFO_RESET >> >> drivers/mmc/host/dw_mmc.c | 25 +++++++++++++++++++++++++ >> drivers/mmc/host/dw_mmc.h | 4 ++++ >> 2 files changed, 29 insertions(+) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 7128351..98e75fc 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -1477,6 +1477,30 @@ static int dw_mci_get_cd(struct mmc_host *mmc) >> return present; >> } >> >> +static void dw_mci_hw_reset(struct mmc_host *mmc) >> +{ >> + struct dw_mci_slot *slot = mmc_priv(mmc); >> + struct dw_mci *host = slot->host; >> + >> + if (host->use_dma == TRANS_MODE_IDMAC) >> + dw_mci_idmac_reset(host); >> + >> + if (!dw_mci_ctrl_reset(host, SDMMC_CTRL_DMA_RESET | >> + SDMMC_CTRL_FIFO_RESET)) >> + return; >> + >> + /* >> + * According to eMMC spec, card reset procedure: >> + * tRstW >= 1us: RST_n pulse width >> + * tRSCA >= 200us: RST_n to Command time >> + * tRSTH >= 1us: RST_n high period >> + */ >> + mci_writel(slot->host, RST_N, SDMMC_RST_HWRESET); > > Even though we used only one slot, but it needs to control bit with slot->id. >
yep, got it.
> Best Regards, > Jaehoon Chung > >> + usleep_range(1, 2); >> + mci_writel(slot->host, RST_N, SDMMC_RST_HWACTIVE); >> + usleep_range(200, 300); >> +} >> + >> static void dw_mci_init_card(struct mmc_host *mmc, struct mmc_card *card) >> { >> struct dw_mci_slot *slot = mmc_priv(mmc); >> @@ -1563,6 +1587,7 @@ static const struct mmc_host_ops dw_mci_ops = { >> .set_ios = dw_mci_set_ios, >> .get_ro = dw_mci_get_ro, >> .get_cd = dw_mci_get_cd, >> + .hw_reset = dw_mci_hw_reset, >> .enable_sdio_irq = dw_mci_enable_sdio_irq, >> .execute_tuning = dw_mci_execute_tuning, >> .card_busy = dw_mci_card_busy, >> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h >> index f695b58..684ee34 100644 >> --- a/drivers/mmc/host/dw_mmc.h >> +++ b/drivers/mmc/host/dw_mmc.h >> @@ -46,6 +46,7 @@ >> #define SDMMC_VERID 0x06c >> #define SDMMC_HCON 0x070 >> #define SDMMC_UHS_REG 0x074 >> +#define SDMMC_RST_N 0x078 >> #define SDMMC_BMOD 0x080 >> #define SDMMC_PLDMND 0x084 >> #define SDMMC_DBADDR 0x088 >> @@ -169,6 +170,9 @@ >> #define SDMMC_IDMAC_ENABLE BIT(7) >> #define SDMMC_IDMAC_FB BIT(1) >> #define SDMMC_IDMAC_SWRESET BIT(0) >> +/* H/W reset */ >> +#define SDMMC_RST_HWACTIVE 0x1 >> +#define SDMMC_RST_HWRESET 0x0 >> /* Version ID register define */ >> #define SDMMC_GET_VERID(x) ((x) & 0xFFFF) >> /* Card read threshold */ >> > > > >
-- Best Regards Shawn Lin
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