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.chung@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> ---
> 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?
> 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.
> /* 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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