Re: [PATCH v2 4/5] mmc: dw-mmc: add the use_hold_reg in CMD register

[Jaehoon Chung <jh80.chung@samsung.com>]

On 08/29/2012 10:21 AM, Seungwon Jeon wrote:
> On Tuesday, August 28, 2012, Jaehoon Chung <jh80.chung@samsung.com> wrote:
>> This patch is added the use_hold_reg bit in CMD register.
>>
>> In upper version than 2.40a, bit[29] of CMD register is used the use_hold_reg.
>> Some SoC is affected by this bit.
>> (This bit means whether use hold register when send data and cmd.
>>  And related with cclk_in_drv phase)
>>
>> Now i known that HOLD-register is using only Exynos-SoC.
>> But hold-register is supported basically feature at Synopsys-IP.
>> If Other SoC is used hold regster, we can change the _CLKSEL_REG_.
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>> ---
>>  drivers/mmc/host/dw_mmc.c  |   36 ++++++++++++++++++++++++++++++++++++
>>  drivers/mmc/host/dw_mmc.h  |    1 +
>>  include/linux/mmc/dw_mmc.h |    3 +++
>>  3 files changed, 40 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 437fdf8..3642455 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -265,11 +265,45 @@ static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
>>  static void dw_mci_start_command(struct dw_mci *host,
>>  				 struct mmc_command *cmd, u32 cmd_flags)
>>  {
>> +	struct dw_mci_slot *slot = host->cur_slot;
>> +	struct mmc_ios *ios = &slot->mmc->ios;
>> +
>>  	host->cmd = cmd;
>>  	dev_vdbg(&host->dev,
>>  		 "start command: ARGR=0x%08x CMDR=0x%08x\n",
>>  		 cmd->arg, cmd_flags);
>>
>> +	if (host->quirks & DW_MCI_QUIRK_USE_CLKSEL_REG) {
> What is this quirk for?
CLKSEL register is only used at the Exynos-SoC.
I didn't know which SoC is used. I added the quirks for Exynos using the CLKSEL register.
> Could you explain?
> 
>> +		/*
>> +		 * If use HOLD register and SDR12/SDSR25,
>> +		 * CMD and DATA sent to card through HOLD regster by default.
>> +		 * But if mode is SDR50/DDR50/SDR104,
>> +		 * only use the hold register when cclk_in_drv value is greater than 0.
>> +		 */
>> +		switch (ios->timing) {
>> +		case MMC_TIMING_UHS_SDR50:
>> +		case MMC_TIMING_UHS_DDR50:
>> +		case MMC_TIMING_UHS_SDR104:
>> +			if (host->pdata->get_clk_drv &&
>> +					host->pdata->get_clk_drv(host) &&
>> +					host->use_hold_reg) {
>> +				cmd_flags |= SDMMC_CMD_USE_HOLD_REG;
>> +				break;
>> +			}
>> +
>> +			cmd_flags &= ~SDMMC_CMD_USE_HOLD_REG;
>> +			break;
>> +		case MMC_TIMING_UHS_SDR12:
>> +		case MMC_TIMING_UHS_SDR25:
>> +			if (host->use_hold_reg) {
>> +				cmd_flags |= SDMMC_CMD_USE_HOLD_REG;
>> +				break;
>> +			}
>> +		default:
>> +			cmd_flags &= ~SDMMC_CMD_USE_HOLD_REG;
>> +		}
>> +	}
>> +
> Considering MMC_TIMING_MMC_HS, MMC_TIMING_SD_HS is omitted.
Sorry, i will fix.
> Didn't you consider moving this whole routine to dw_mci_set_ios?
> When deciding the timing, once seems to be enough.
Well, i considered that move the code into dw_mci_set_ios().
But cmd_flags is set before sending the command at every time.
Finally, hold_regs bit must be also set at every time.
We can prevent to set the cmd_flags at every time.

Best Regards,
Jaehoon Chung
> 
> Thanks,
> Seungwon Jeon
> 
>>  	mci_writel(host, CMDARG, cmd->arg);
>>  	wmb();
>>
>> @@ -2015,6 +2049,8 @@ int dw_mci_probe(struct dw_mci *host)
>>  		host->data_shift = 2;
>>  	}
>>
>> +	host->use_hold_reg = (mci_readl(host, HCON) >> 22) & 0x1;
>> +
>>  	/* Reset all blocks */
>>  	if (!mci_wait_reset(&host->dev, host))
>>  		return -ENODEV;
>> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
>> index b6a1a78..cc905ee 100644
>> --- a/drivers/mmc/host/dw_mmc.h
>> +++ b/drivers/mmc/host/dw_mmc.h
>> @@ -111,6 +111,7 @@
>>  #define SDMMC_INT_ERROR			0xbfc2
>>  /* Command register defines */
>>  #define SDMMC_CMD_START			BIT(31)
>> +#define SDMMC_CMD_USE_HOLD_REG		BIT(29)
>>  #define SDMMC_CMD_CCS_EXP		BIT(23)
>>  #define SDMMC_CMD_CEATA_RD		BIT(22)
>>  #define SDMMC_CMD_UPD_CLK		BIT(21)
>> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
>> index f20979c..803a80d 100644
>> --- a/include/linux/mmc/dw_mmc.h
>> +++ b/include/linux/mmc/dw_mmc.h
>> @@ -156,6 +156,7 @@ struct dw_mci {
>>  	u32			fifoth_val;
>>  	u16			verid;
>>  	u16			data_offset;
>> +	bool			use_hold_reg;
>>  	struct device		dev;
>>  	struct dw_mci_board	*pdata;
>>  	struct dw_mci_slot	*slot[MAX_MCI_SLOTS];
>> @@ -201,6 +202,8 @@ struct dw_mci_dma_ops {
>>  #define DW_MCI_QUIRK_HIGHSPEED			BIT(2)
>>  /* Unreliable card detection */
>>  #define DW_MCI_QUIRK_BROKEN_CARD_DETECTION	BIT(3)
>> +/* To use the CLKSEL register for phase-shift */
>> +#define DW_MCI_QUIRK_USE_CLKSEL_REG		BIT(4)
>>
>>
>>  struct dma_pdata;
>> --
>> 1.7.4.1
> 
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