linux-kernel - Re: [PATCH v3] mmc: dw_mmc: add hw

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Date:	Wed, 20 Jan 2016 12:26:08 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Jaehoon Chung <jh80.chung@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	shawn.lin@...k-chips.com, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] mmc: dw_mmc: add hw_reset support

On 2016/1/20 12:24, Jaehoon Chung wrote:
> Hi, Shawn.
>
> On 01/14/2016 10:08 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.
>>
>> Set the following resets:
>> software reset – BMOD[0] for IDMAC only
>> DMA reset– CTRL[2]
>> FIFO reset – CTRL[1] bits
>>
>> Program the CARD_RESET register with a value of 0 for the bit
>> corresponding to the card number; This programming asserts the
>> RST_n signal and resets the card. After a minimum of 1 μs, de-asserts the
>> RST_n signal and takes the card out of reset. The application can program
>> a new CMD only after a minimum of 200 us
>>
>> This implementation can be easily tested by cutting off->On vmmc
>> while doing data accessing in background to simulate that case.
>>
>> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
>>
>> ---
>>
>> Changes in v3:
>> - reset for each slot
>> - simply the commit msg
>>
>> 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 | 29 +++++++++++++++++++++++++++++
>>   drivers/mmc/host/dw_mmc.h |  3 +++
>>   2 files changed, 32 insertions(+)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 7128351..fddbcb6 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -1477,6 +1477,34 @@ 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;
>> +	int reset;
>> +
>> +	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
>> +	 */
>> +	reset = mci_readl(host, RST_N);
>> +	reset &= ~(SDMMC_RST_HWACTIVE << slot->id);
>> +	mci_writel(slot->host, RST_N, reset);
>
> I will pick this patch, after change "host" instead of "slot->host".
> (I will change it when i apply this.)
>
> Thanks!

Thanks, Jaehoon. :)

>
> Best Regards,
> Jaehoon Chung
>
>> +	usleep_range(1, 2);
>> +	reset |= SDMMC_RST_HWACTIVE << slot->id;
>> +	mci_writel(slot->host, RST_N, reset);
>> +	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 +1591,7 @@ 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..a14b7fc 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 +170,8 @@
>>   #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
>>   /* Version ID register define */
>>   #define SDMMC_GET_VERID(x)		((x) & 0xFFFF)
>>   /* Card read threshold */
>>
>
>
>
>


-- 
Best Regards
Shawn Lin