[PATCHv6,1/5] mmc: dw_mmc: Add support to set the SDR and DDR timing through clock framework

Commit Message

Dinh Nguyen Dec. 12, 2013, 8:30 p.m. UTC

From: Dinh Nguyen <[e-mail]>

All implementations of the Synopsys DW SD/MMC IP have settings to control
the phase shift of the CIU clk. These phase shift settings are necessary for
the SD/MMC to correctly clock the card. All variants of the dw_mmc will need
these settings, but how they are implemented can vastly vary.

This patch enables the setting for the SDR and/or DDR settings through the
common clock framework.

Depends on the patch "mmc: dw_mmc: Enable the hold reg for certain speed modes",
that is already reading the "samsung,dw-mshc-sdr-timing" and
"samsung,dw-mshc-ddr-timing" bindings, this patch saves those values into a
u32 bitmask that can be passed to the clock framework to use.

Signed-off-by: Dinh Nguyen <[e-mail]>
---
v6: Add this patch
v5: none
v4: none
v3: none
v2: none
---
 drivers/mmc/host/dw_mmc.c  |   23 +++++++++++++++++++++++
 include/linux/mmc/dw_mmc.h |    6 ++++++
 2 files changed, 29 insertions(+)

Comments

Zhangfei Gao Dec. 15, 2013, 2:05 a.m. UTC | #1

Dear Dinh

On 12/13/2013 04:30 AM, [e-mail] wrote:
> From: Dinh Nguyen <[e-mail]>
>
> All implementations of the Synopsys DW SD/MMC IP have settings to control
> the phase shift of the CIU clk. These phase shift settings are necessary for
> the SD/MMC to correctly clock the card. All variants of the dw_mmc will need
> these settings, but how they are implemented can vastly vary.
>
> This patch enables the setting for the SDR and/or DDR settings through the
> common clock framework.
>
> Depends on the patch "mmc: dw_mmc: Enable the hold reg for certain speed modes",
> that is already reading the "samsung,dw-mshc-sdr-timing" and
> "samsung,dw-mshc-ddr-timing" bindings, this patch saves those values into a
> u32 bitmask that can be passed to the clock framework to use.
>
> Signed-off-by: Dinh Nguyen <[e-mail]>
> ---
> v6: Add this patch
> v5: none
> v4: none
> v3: none
> v2: none
> ---
>   drivers/mmc/host/dw_mmc.c  |   23 +++++++++++++++++++++++
>   include/linux/mmc/dw_mmc.h |    6 ++++++
>   2 files changed, 29 insertions(+)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 480dafe..1fb5cff 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -2431,6 +2431,8 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
>   	if ((sdr_timing[1] == 0) || (ddr_timing[1] == 0))
>   		pdata->cclk_in_drv = 0;
>
> +	pdata->sdr_timing = (sdr_timing[1] | (sdr_timing[0] << 4));
> +	pdata->ddr_timing = (ddr_timing[1] | (ddr_timing[0] << 4));
>   	return pdata;
>   }
>
> @@ -2478,6 +2480,27 @@ int dw_mci_probe(struct dw_mci *host)
>   		dev_dbg(host->dev, "ciu clock not available\n");
>   		host->bus_hz = host->pdata->bus_hz;
>   	} else {
> +		/* If the CIU clk is available, we check for SDR and DDR
> +		 * timing phase shift settings. But not all platforms
> +		 * may have populated these settings, the driver will not fail
> +		 * if these settings are not specified.
> +		 */
> +		if (host->pdata->sdr_timing) {
> +			host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
> +			if (IS_ERR(host->sdr_clk))
> +				dev_dbg(host->dev, "sdr_mmc clock not available\n");
> +			else
> +				clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
> +		}
> +
> +		if (host->pdata->ddr_timing) {
> +			host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
> +			if (IS_ERR(host->ddr_clk))
> +				dev_dbg(host->dev, "ddr_mmc clock not available\n");
> +			else
> +				clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
> +		}
> +

Just curious, does pdata->sdr_timing and pdata->ddr_timing are fixed, 
fixed as each controller, or different with different board.
In case they are fixed, or fixed in each controller, and only required 
to be set in probe only once, maybe they can be hide in clk_mmc_ops.prepare
And the clock can be used as ciu_clock, or parent of ciu_clock, which is 
called in dw_mmc.c, maybe these code can be ignored.



>   		ret = clk_prepare_enable(host->ciu_clk);
>   		if (ret) {
>   			dev_err(host->dev, "failed to enable ciu clock\n");
> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
> index 2b5b8bf..ad90ad1 100644
> --- a/include/linux/mmc/dw_mmc.h
> +++ b/include/linux/mmc/dw_mmc.h
> @@ -83,6 +83,8 @@ struct mmc_data;
>    * @priv: Implementation defined private data.
>    * @biu_clk: Pointer to bus interface unit clock instance.
>    * @ciu_clk: Pointer to card interface unit clock instance.
> + * @sdr_clk: Pointer to the SDR clock instance.
> + * @ddr_clk: Pointer to the DDR clock instance.
>    * @slot: Slots sharing this MMC controller.
>    * @fifo_depth: depth of FIFO.
>    * @data_shift: log2 of FIFO item size.
> @@ -170,6 +172,8 @@ struct dw_mci {
>   	void			*priv;
>   	struct clk		*biu_clk;
>   	struct clk		*ciu_clk;
> +	struct clk		*sdr_clk;
> +	struct clk		*ddr_clk;
>   	struct dw_mci_slot	*slot[MAX_MCI_SLOTS];
>
>   	/* FIFO push and pull */
> @@ -241,6 +245,8 @@ struct dw_mci_board {
>   	u32 caps2;	/* More capabilities */
>   	u32 pm_caps;	/* PM capabilities */
>   	u32 cclk_in_drv;	/*cclk_in_drv phase shift */
> +	u32 sdr_timing;	/* Single data rate timing setting. */
> +	u32 ddr_timing;	/* Double data rate timing setting. */

Are they fixed or not?

Thanks
Zhangfei

Dinh Nguyen Dec. 15, 2013, 3:16 a.m. UTC | #2

Hi Zhangfei,

On 12/14/13 8:05 PM, zhangfei wrote:
> Dear Dinh
>
> On 12/13/2013 04:30 AM, [e-mail] wrote:
>> From: Dinh Nguyen <[e-mail]>
>>
>> All implementations of the Synopsys DW SD/MMC IP have settings to
>> control
>> the phase shift of the CIU clk. These phase shift settings are
>> necessary for
>> the SD/MMC to correctly clock the card. All variants of the dw_mmc
>> will need
>> these settings, but how they are implemented can vastly vary.
>>
>> This patch enables the setting for the SDR and/or DDR settings
>> through the
>> common clock framework.
>>
>> Depends on the patch "mmc: dw_mmc: Enable the hold reg for certain
>> speed modes",
>> that is already reading the "samsung,dw-mshc-sdr-timing" and
>> "samsung,dw-mshc-ddr-timing" bindings, this patch saves those values
>> into a
>> u32 bitmask that can be passed to the clock framework to use.
>>
>> Signed-off-by: Dinh Nguyen <[e-mail]>
>> ---
>> v6: Add this patch
>> v5: none
>> v4: none
>> v3: none
>> v2: none
>> ---
>>   drivers/mmc/host/dw_mmc.c  |   23 +++++++++++++++++++++++
>>   include/linux/mmc/dw_mmc.h |    6 ++++++
>>   2 files changed, 29 insertions(+)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 480dafe..1fb5cff 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -2431,6 +2431,8 @@ static struct dw_mci_board
>> *dw_mci_parse_dt(struct dw_mci *host)
>>       if ((sdr_timing[1] == 0) || (ddr_timing[1] == 0))
>>           pdata->cclk_in_drv = 0;
>>
>> +    pdata->sdr_timing = (sdr_timing[1] | (sdr_timing[0] << 4));
>> +    pdata->ddr_timing = (ddr_timing[1] | (ddr_timing[0] << 4));
>>       return pdata;
>>   }
>>
>> @@ -2478,6 +2480,27 @@ int dw_mci_probe(struct dw_mci *host)
>>           dev_dbg(host->dev, "ciu clock not available\n");
>>           host->bus_hz = host->pdata->bus_hz;
>>       } else {
>> +        /* If the CIU clk is available, we check for SDR and DDR
>> +         * timing phase shift settings. But not all platforms
>> +         * may have populated these settings, the driver will not fail
>> +         * if these settings are not specified.
>> +         */
>> +        if (host->pdata->sdr_timing) {
>> +            host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
>> +            if (IS_ERR(host->sdr_clk))
>> +                dev_dbg(host->dev, "sdr_mmc clock not available\n");
>> +            else
>> +                clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
>> +        }
>> +
>> +        if (host->pdata->ddr_timing) {
>> +            host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
>> +            if (IS_ERR(host->ddr_clk))
>> +                dev_dbg(host->dev, "ddr_mmc clock not available\n");
>> +            else
>> +                clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
>> +        }
>> +
>
> Just curious, does pdata->sdr_timing and pdata->ddr_timing are fixed,
> fixed as each controller, or different with different board.
Yes, they are fixed for each controller per SoC.
> In case they are fixed, or fixed in each controller, and only required
> to be set in probe only once, maybe they can be hide in
> clk_mmc_ops.prepare
> And the clock can be used as ciu_clock, or parent of ciu_clock, which
> is called in dw_mmc.c, maybe these code can be ignored.
>
Please see v5 of this patch: https://patchwork.kernel.org/patch/3311121/
The issue with V5 was that there is no way for the dw_mmc driver to pass
the clock phase settings
in the clk_mmc_ops.prepare function.
>
>
>>           ret = clk_prepare_enable(host->ciu_clk);
>>           if (ret) {
>>               dev_err(host->dev, "failed to enable ciu clock\n");
>> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
>> index 2b5b8bf..ad90ad1 100644
>> --- a/include/linux/mmc/dw_mmc.h
>> +++ b/include/linux/mmc/dw_mmc.h
>> @@ -83,6 +83,8 @@ struct mmc_data;
>>    * @priv: Implementation defined private data.
>>    * @biu_clk: Pointer to bus interface unit clock instance.
>>    * @ciu_clk: Pointer to card interface unit clock instance.
>> + * @sdr_clk: Pointer to the SDR clock instance.
>> + * @ddr_clk: Pointer to the DDR clock instance.
>>    * @slot: Slots sharing this MMC controller.
>>    * @fifo_depth: depth of FIFO.
>>    * @data_shift: log2 of FIFO item size.
>> @@ -170,6 +172,8 @@ struct dw_mci {
>>       void            *priv;
>>       struct clk        *biu_clk;
>>       struct clk        *ciu_clk;
>> +    struct clk        *sdr_clk;
>> +    struct clk        *ddr_clk;
>>       struct dw_mci_slot    *slot[MAX_MCI_SLOTS];
>>
>>       /* FIFO push and pull */
>> @@ -241,6 +245,8 @@ struct dw_mci_board {
>>       u32 caps2;    /* More capabilities */
>>       u32 pm_caps;    /* PM capabilities */
>>       u32 cclk_in_drv;    /*cclk_in_drv phase shift */
>> +    u32 sdr_timing;    /* Single data rate timing setting. */
>> +    u32 ddr_timing;    /* Double data rate timing setting. */
>
> Are they fixed or not?
They are fixed values that is represented in the DTS bindings.

Dinh
>
> Thanks
> Zhangfei

Zhangfei Gao Dec. 15, 2013, 4:37 a.m. UTC | #3

On 12/15/2013 11:16 AM, Dinh Nguyen wrote:
> Hi Zhangfei,
>
>>> @@ -2478,6 +2480,27 @@ int dw_mci_probe(struct dw_mci *host)
>>>            dev_dbg(host->dev, "ciu clock not available\n");
>>>            host->bus_hz = host->pdata->bus_hz;
>>>        } else {
>>> +        /* If the CIU clk is available, we check for SDR and DDR
>>> +         * timing phase shift settings. But not all platforms
>>> +         * may have populated these settings, the driver will not fail
>>> +         * if these settings are not specified.
>>> +         */
>>> +        if (host->pdata->sdr_timing) {
>>> +            host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
>>> +            if (IS_ERR(host->sdr_clk))
>>> +                dev_dbg(host->dev, "sdr_mmc clock not available\n");
>>> +            else
>>> +                clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
>>> +        }
>>> +
>>> +        if (host->pdata->ddr_timing) {
>>> +            host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
>>> +            if (IS_ERR(host->ddr_clk))
>>> +                dev_dbg(host->dev, "ddr_mmc clock not available\n");
>>> +            else
>>> +                clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
>>> +        }
>>> +
>>
>> Just curious, does pdata->sdr_timing and pdata->ddr_timing are fixed,
>> fixed as each controller, or different with different board.
> Yes, they are fixed for each controller per SoC.
>> In case they are fixed, or fixed in each controller, and only required
>> to be set in probe only once, maybe they can be hide in
>> clk_mmc_ops.prepare
>> And the clock can be used as ciu_clock, or parent of ciu_clock, which
>> is called in dw_mmc.c, maybe these code can be ignored.
>>
> Please see v5 of this patch: https://patchwork.kernel.org/patch/3311121/
> The issue with V5 was that there is no way for the dw_mmc driver to pass
> the clock phase settings
> in the clk_mmc_ops.prepare function.

Personally, I think v5 is simpler :)

Could these fixed para be used as internal para when register.
Like
socfpga_gate_clk_init
rc = of_property_read_u32_array(node, "clk-gate", clk_gate, 2);
         compatible = "altr,socfpga-gate-clk";
	clocks = <&mainclk>;
	div-reg = <0x64 0 2>;
	clk-gate = <0x60 1>;
Could we also define mmc-ciu-clock with para clk-init.

Thanks

Dinh Nguyen Dec. 16, 2013, 3:24 a.m. UTC | #4

On 12/14/13 10:37 PM, zhangfei wrote:
>
>
> On 12/15/2013 11:16 AM, Dinh Nguyen wrote:
>> Hi Zhangfei,
>>
>>>> @@ -2478,6 +2480,27 @@ int dw_mci_probe(struct dw_mci *host)
>>>>            dev_dbg(host->dev, "ciu clock not available\n");
>>>>            host->bus_hz = host->pdata->bus_hz;
>>>>        } else {
>>>> +        /* If the CIU clk is available, we check for SDR and DDR
>>>> +         * timing phase shift settings. But not all platforms
>>>> +         * may have populated these settings, the driver will not
>>>> fail
>>>> +         * if these settings are not specified.
>>>> +         */
>>>> +        if (host->pdata->sdr_timing) {
>>>> +            host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
>>>> +            if (IS_ERR(host->sdr_clk))
>>>> +                dev_dbg(host->dev, "sdr_mmc clock not available\n");
>>>> +            else
>>>> +                clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
>>>> +        }
>>>> +
>>>> +        if (host->pdata->ddr_timing) {
>>>> +            host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
>>>> +            if (IS_ERR(host->ddr_clk))
>>>> +                dev_dbg(host->dev, "ddr_mmc clock not available\n");
>>>> +            else
>>>> +                clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
>>>> +        }
>>>> +
>>>
>>> Just curious, does pdata->sdr_timing and pdata->ddr_timing are fixed,
>>> fixed as each controller, or different with different board.
>> Yes, they are fixed for each controller per SoC.
>>> In case they are fixed, or fixed in each controller, and only required
>>> to be set in probe only once, maybe they can be hide in
>>> clk_mmc_ops.prepare
>>> And the clock can be used as ciu_clock, or parent of ciu_clock, which
>>> is called in dw_mmc.c, maybe these code can be ignored.
>>>
>> Please see v5 of this patch: https://patchwork.kernel.org/patch/3311121/
>> The issue with V5 was that there is no way for the dw_mmc driver to pass
>> the clock phase settings
>> in the clk_mmc_ops.prepare function.
>
> Personally, I think v5 is simpler :)
I agree...
>
> Could these fixed para be used as internal para when register.
> Like
> socfpga_gate_clk_init
> rc = of_property_read_u32_array(node, "clk-gate", clk_gate, 2);
>         compatible = "altr,socfpga-gate-clk";
>     clocks = <&mainclk>;
>     div-reg = <0x64 0 2>;
>     clk-gate = <0x60 1>;
> Could we also define mmc-ciu-clock with para clk-init.
Hmm..this was one of Arnd's suggestion. Will this also work for you? If
so then I think I can
proceed down this path, as I think this should be the most direct and
simplest.

Thanks,
Dinh
>
> Thanks

Zhangfei Gao Dec. 16, 2013, 3:38 a.m. UTC | #5

On 16 December 2013 11:24, Dinh Nguyen <[e-mail]> wrote:
>
>>>>> @@ -2478,6 +2480,27 @@ int dw_mci_probe(struct dw_mci *host)
>>>>>            dev_dbg(host->dev, "ciu clock not available\n");
>>>>>            host->bus_hz = host->pdata->bus_hz;
>>>>>        } else {
>>>>> +        /* If the CIU clk is available, we check for SDR and DDR
>>>>> +         * timing phase shift settings. But not all platforms
>>>>> +         * may have populated these settings, the driver will not
>>>>> fail
>>>>> +         * if these settings are not specified.
>>>>> +         */
>>>>> +        if (host->pdata->sdr_timing) {
>>>>> +            host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
>>>>> +            if (IS_ERR(host->sdr_clk))
>>>>> +                dev_dbg(host->dev, "sdr_mmc clock not available\n");
>>>>> +            else
>>>>> +                clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
>>>>> +        }
>>>>> +
>>>>> +        if (host->pdata->ddr_timing) {
>>>>> +            host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
>>>>> +            if (IS_ERR(host->ddr_clk))
>>>>> +                dev_dbg(host->dev, "ddr_mmc clock not available\n");
>>>>> +            else
>>>>> +                clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
>>>>> +        }
>>>>> +
>>>>
>>>> Just curious, does pdata->sdr_timing and pdata->ddr_timing are fixed,
>>>> fixed as each controller, or different with different board.
>>> Yes, they are fixed for each controller per SoC.
>>>> In case they are fixed, or fixed in each controller, and only required
>>>> to be set in probe only once, maybe they can be hide in
>>>> clk_mmc_ops.prepare
>>>> And the clock can be used as ciu_clock, or parent of ciu_clock, which
>>>> is called in dw_mmc.c, maybe these code can be ignored.
>>>>
>>> Please see v5 of this patch: https://patchwork.kernel.org/patch/3311121/
>>> The issue with V5 was that there is no way for the dw_mmc driver to pass
>>> the clock phase settings
>>> in the clk_mmc_ops.prepare function.
>>
>> Personally, I think v5 is simpler :)
> I agree...
>>
>> Could these fixed para be used as internal para when register.
>> Like
>> socfpga_gate_clk_init
>> rc = of_property_read_u32_array(node, "clk-gate", clk_gate, 2);
>>         compatible = "altr,socfpga-gate-clk";
>>     clocks = <&mainclk>;
>>     div-reg = <0x64 0 2>;
>>     clk-gate = <0x60 1>;
>> Could we also define mmc-ciu-clock with para clk-init.
> Hmm..this was one of Arnd's suggestion. Will this also work for you? If
> so then I think I can
> proceed down this path, as I think this should be the most direct and
> simplest.
>

Yes, go ahead.
sdr_timing & ddr_timing only takes effect on socfpga-mmc.
It is good to put in clk driver specifically for socfpga, instead of
putting in common dw_mmc.c

Thanks

Seungwon Jeon Dec. 16, 2013, 4:20 a.m. UTC | #6

On Friday, December 13, 2013, Dinh Nguyen wrote:
> From: Dinh Nguyen <[e-mail]>
> 
> All implementations of the Synopsys DW SD/MMC IP have settings to control
> the phase shift of the CIU clk. These phase shift settings are necessary for
> the SD/MMC to correctly clock the card. All variants of the dw_mmc will need
> these settings, but how they are implemented can vastly vary.
> 
> This patch enables the setting for the SDR and/or DDR settings through the
> common clock framework.
> 
> Depends on the patch "mmc: dw_mmc: Enable the hold reg for certain speed modes",
> that is already reading the "samsung,dw-mshc-sdr-timing" and
> "samsung,dw-mshc-ddr-timing" bindings, this patch saves those values into a
> u32 bitmask that can be passed to the clock framework to use.

I didn't understand this patch.
As you mentioned, clock implementation can be different each SOC.
And what is the difference with existing ciu clock?

> 
> Signed-off-by: Dinh Nguyen <[e-mail]>
> ---
> v6: Add this patch
> v5: none
> v4: none
> v3: none
> v2: none
> ---
>  drivers/mmc/host/dw_mmc.c  |   23 +++++++++++++++++++++++
>  include/linux/mmc/dw_mmc.h |    6 ++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 480dafe..1fb5cff 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -2431,6 +2431,8 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
>  	if ((sdr_timing[1] == 0) || (ddr_timing[1] == 0))
>  		pdata->cclk_in_drv = 0;
> 
> +	pdata->sdr_timing = (sdr_timing[1] | (sdr_timing[0] << 4));
> +	pdata->ddr_timing = (ddr_timing[1] | (ddr_timing[0] << 4));
Can you explain what it is for?

Thanks,
Seungwon

>  	return pdata;
>  }
> 
> @@ -2478,6 +2480,27 @@ int dw_mci_probe(struct dw_mci *host)
>  		dev_dbg(host->dev, "ciu clock not available\n");
>  		host->bus_hz = host->pdata->bus_hz;
>  	} else {
> +		/* If the CIU clk is available, we check for SDR and DDR
> +		 * timing phase shift settings. But not all platforms
> +		 * may have populated these settings, the driver will not fail
> +		 * if these settings are not specified.
> +		 */
> +		if (host->pdata->sdr_timing) {
> +			host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
> +			if (IS_ERR(host->sdr_clk))
> +				dev_dbg(host->dev, "sdr_mmc clock not available\n");
> +			else
> +				clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
> +		}
> +
> +		if (host->pdata->ddr_timing) {
> +			host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
> +			if (IS_ERR(host->ddr_clk))
> +				dev_dbg(host->dev, "ddr_mmc clock not available\n");
> +			else
> +				clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
> +		}
> +
>  		ret = clk_prepare_enable(host->ciu_clk);
>  		if (ret) {
>  			dev_err(host->dev, "failed to enable ciu clock\n");
> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
> index 2b5b8bf..ad90ad1 100644
> --- a/include/linux/mmc/dw_mmc.h
> +++ b/include/linux/mmc/dw_mmc.h
> @@ -83,6 +83,8 @@ struct mmc_data;
>   * @priv: Implementation defined private data.
>   * @biu_clk: Pointer to bus interface unit clock instance.
>   * @ciu_clk: Pointer to card interface unit clock instance.
> + * @sdr_clk: Pointer to the SDR clock instance.
> + * @ddr_clk: Pointer to the DDR clock instance.
>   * @slot: Slots sharing this MMC controller.
>   * @fifo_depth: depth of FIFO.
>   * @data_shift: log2 of FIFO item size.
> @@ -170,6 +172,8 @@ struct dw_mci {
>  	void			*priv;
>  	struct clk		*biu_clk;
>  	struct clk		*ciu_clk;
> +	struct clk		*sdr_clk;
> +	struct clk		*ddr_clk;
>  	struct dw_mci_slot	*slot[MAX_MCI_SLOTS];
> 
>  	/* FIFO push and pull */
> @@ -241,6 +245,8 @@ struct dw_mci_board {
>  	u32 caps2;	/* More capabilities */
>  	u32 pm_caps;	/* PM capabilities */
>  	u32 cclk_in_drv;	/*cclk_in_drv phase shift */
> +	u32 sdr_timing;	/* Single data rate timing setting. */
> +	u32 ddr_timing;	/* Double data rate timing setting. */
>  	/*
>  	 * Override fifo depth. If 0, autodetect it from the FIFOTH register,
>  	 * but note that this may not be reliable after a bootloader has used
> --
> 1.7.9.5
> 
> 
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Patch

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 480dafe..1fb5cff 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2431,6 +2431,8 @@  static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
 	if ((sdr_timing[1] == 0) || (ddr_timing[1] == 0))
 		pdata->cclk_in_drv = 0;
 
+	pdata->sdr_timing = (sdr_timing[1] | (sdr_timing[0] << 4));
+	pdata->ddr_timing = (ddr_timing[1] | (ddr_timing[0] << 4));
 	return pdata;
 }
 
@@ -2478,6 +2480,27 @@  int dw_mci_probe(struct dw_mci *host)
 		dev_dbg(host->dev, "ciu clock not available\n");
 		host->bus_hz = host->pdata->bus_hz;
 	} else {
+		/* If the CIU clk is available, we check for SDR and DDR
+		 * timing phase shift settings. But not all platforms
+		 * may have populated these settings, the driver will not fail
+		 * if these settings are not specified.
+		 */
+		if (host->pdata->sdr_timing) {
+			host->sdr_clk = devm_clk_get(host->dev, "sdr_mmc_clk");
+			if (IS_ERR(host->sdr_clk))
+				dev_dbg(host->dev, "sdr_mmc clock not available\n");
+			else
+				clk_set_rate(host->sdr_clk, host->pdata->sdr_timing);
+		}
+
+		if (host->pdata->ddr_timing) {
+			host->ddr_clk = devm_clk_get(host->dev, "ddr_mmc_clk");
+			if (IS_ERR(host->ddr_clk))
+				dev_dbg(host->dev, "ddr_mmc clock not available\n");
+			else
+				clk_set_rate(host->ddr_clk, host->pdata->ddr_timing);
+		}
+
 		ret = clk_prepare_enable(host->ciu_clk);
 		if (ret) {
 			dev_err(host->dev, "failed to enable ciu clock\n");
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index 2b5b8bf..ad90ad1 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -83,6 +83,8 @@  struct mmc_data;
  * @priv: Implementation defined private data.
  * @biu_clk: Pointer to bus interface unit clock instance.
  * @ciu_clk: Pointer to card interface unit clock instance.
+ * @sdr_clk: Pointer to the SDR clock instance.
+ * @ddr_clk: Pointer to the DDR clock instance.
  * @slot: Slots sharing this MMC controller.
  * @fifo_depth: depth of FIFO.
  * @data_shift: log2 of FIFO item size.
@@ -170,6 +172,8 @@  struct dw_mci {
 	void			*priv;
 	struct clk		*biu_clk;
 	struct clk		*ciu_clk;
+	struct clk		*sdr_clk;
+	struct clk		*ddr_clk;
 	struct dw_mci_slot	*slot[MAX_MCI_SLOTS];
 
 	/* FIFO push and pull */
@@ -241,6 +245,8 @@  struct dw_mci_board {
 	u32 caps2;	/* More capabilities */
 	u32 pm_caps;	/* PM capabilities */
 	u32 cclk_in_drv;	/*cclk_in_drv phase shift */
+	u32 sdr_timing;	/* Single data rate timing setting. */
+	u32 ddr_timing;	/* Double data rate timing setting. */
 	/*
 	 * Override fifo depth. If 0, autodetect it from the FIFOTH register,
 	 * but note that this may not be reliable after a bootloader has used