Hi James
On 09/30/2011 08:05 PM, James Hogan wrote:
> Hi,
>
> On 09/30/2011 11:46 AM, Jaehoon Chung wrote:
>> This patch is added the use_hold_reg bit in CMD register.
>>
>> In 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)
>> if set IMPLEMENT_HOLD_REG in HCON register, i think fine that set this
>> bit by default.
>>
>> Signed-off-by: Jaehoon Chung <jh80.ch...@samsung.com>
>> Signed-off-by: Kyungmin Park <kyungmin.p...@samsung.com>
>> ---
>> drivers/mmc/host/dw_mmc.c | 9 +++++++++
>> drivers/mmc/host/dw_mmc.h | 1 +
>> include/linux/mmc/dw_mmc.h | 1 +
>> 3 files changed, 11 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 0ed1d28..544a616 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -276,6 +276,13 @@ static void dw_mci_start_command(struct dw_mci *host,
>> mci_writel(host, CMDARG, cmd->arg);
>> wmb();
>>
>> + /*
>> + * If use HOLD register,
>> + * CMD and DATA sent to card through HOLD register.
>> + */
>> + if (host->use_hold_reg)
>> + cmd_flags |= SDMMC_CMD_USE_HOLD_REG;
>> +
>
> Is the HOLD register an internal register that is always required for
> hardware that has it to work? What effect does it have on the transaction?
I known that it's internal register. if we used hold register, it should
be work to delay cclk_in to drive the card output.
>
>> mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START);
>> }
>>
>> @@ -1886,6 +1893,8 @@ static int dw_mci_probe(struct platform_device *pdev)
>> host->data_shift = 2;
>> }
>>
>> + host->use_hold_reg = (mci_readl(host, HCON) >> 22) & 0x1;
>> +
>
> it'd be nice to have a #define for the HCON bit.
I will add a #define for the HCON
>
>> /* Reset all blocks */
>> if (!mci_wait_reset(&pdev->dev, host)) {
>> ret = -ENODEV;
>> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
>> index bfa3c1c..8c4edca 100644
>> --- a/drivers/mmc/host/dw_mmc.h
>> +++ b/drivers/mmc/host/dw_mmc.h
>> @@ -102,6 +102,7 @@
>> #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 6b46819..d6d1515 100644
>> --- a/include/linux/mmc/dw_mmc.h
>> +++ b/include/linux/mmc/dw_mmc.h
>> @@ -147,6 +147,7 @@ struct dw_mci {
>> u32 current_speed;
>> u32 num_slots;
>> u32 fifoth_val;
>> + bool use_hold_reg;
>
> in case of other similar bits being added it may be better to have a
> copy of the hcon register here, but its fine as it is too.
>
>> struct platform_device *pdev;
>> struct dw_mci_board *pdata;
>> struct dw_mci_slot *slot[MAX_MCI_SLOTS];
>
> Cheers
> James
>
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