[U-Boot] [PATCH] MMC: DWMMC: Correct the CLKDIV register value

[Jaehoon Chung]

On 09/11/2013 02:28 PM, Rajeshwari Birje wrote:
> Hi All,
> 
> Please do let me know if any comments on the same.
> 
> Regards,
> Rajeshwari Shinde.
> 
> On Thu, Aug 29, 2013 at 4:34 PM, Rajeshwari Birje
> <rajeshwari.birje at gmail.com> wrote:
>> CCing the MMC Maintainer.
>>
>> On Thu, Aug 29, 2013 at 4:22 PM, Rajeshwari S Shinde
>> <rajeshwari.s at samsung.com> wrote:
>>> This patch corrects the divider value written to CLKDIV register.
>>> Since SDCLKIN is divided inside controller by the DIVRATIO value set
>>> in the CLKSEL register, we need to use the same output clock value to
>>> calculate the CLKDIV value.
>>> as per user manual: cclk_in = SDCLKIN / (DIVRATIO + 1)
>>>
>>> Input parameter to mmc_clk is changed to dwmci_host, since
>>> we need the same to read DWMCI_CLKSEL register.
>>>
>>> This improves the read timing values for channel 0 on SMDK5250
>>> from 0.288sec to 0.144sec
>>>
>>> Signed-off-by: Rajeshwari S Shinde <rajeshwari.s at samsung.com>
>>> ---
>>>  arch/arm/include/asm/arch-exynos/dwmmc.h |  4 ++++
>>>  drivers/mmc/dw_mmc.c                     |  2 +-
>>>  drivers/mmc/exynos_dw_mmc.c              | 17 +++++++++++++++--
>>>  include/dwmmc.h                          |  2 +-
>>>  4 files changed, 21 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm/include/asm/arch-exynos/dwmmc.h b/arch/arm/include/asm/arch-exynos/dwmmc.h
>>> index b9eca76..f1c8d8a 100644
>>> --- a/arch/arm/include/asm/arch-exynos/dwmmc.h
>>> +++ b/arch/arm/include/asm/arch-exynos/dwmmc.h
>>> @@ -14,6 +14,10 @@
>>>  #define DWMCI_SET_DRV_CLK(x)   ((x) << 16)
>>>  #define DWMCI_SET_DIV_RATIO(x) ((x) << 24)
>>>
>>> +/* CLKSEL Register */
>>> +#define DWMCI_DIVRATIO_BIT             24
>>> +#define DWMCI_DIVRATIO_MASK            0x7
>>> +
>>>  #ifdef CONFIG_OF_CONTROL
>>>  int exynos_dwmmc_init(const void *blob);
>>>  #endif
>>> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
>>> index a82ee17..3406bdd 100644
>>> --- a/drivers/mmc/dw_mmc.c
>>> +++ b/drivers/mmc/dw_mmc.c
>>> @@ -224,7 +224,7 @@ static int dwmci_setup_bus(struct dwmci_host *host, u32 freq)
>>>          * host->bus_hz should be set from user.
>>>          */
>>>         if (host->mmc_clk)
>>> -               sclk = host->mmc_clk(host->dev_index);
>>> +               sclk = host->mmc_clk(host);
>>>         else if (host->bus_hz)
>>>                 sclk = host->bus_hz;
>>>         else {
>>> diff --git a/drivers/mmc/exynos_dw_mmc.c b/drivers/mmc/exynos_dw_mmc.c
>>> index 4ef9fec..1ed4afe 100644
>>> --- a/drivers/mmc/exynos_dw_mmc.c
>>> +++ b/drivers/mmc/exynos_dw_mmc.c
>>> @@ -29,9 +29,22 @@ static void exynos_dwmci_clksel(struct dwmci_host *host)
>>>         dwmci_writel(host, DWMCI_CLKSEL, host->clksel_val);
>>>  }
>>>
>>> -unsigned int exynos_dwmci_get_clk(int dev_index)
>>> +unsigned int exynos_dwmci_get_clk(struct dwmci_host *host)
>>>  {
>>> -       return get_mmc_clk(dev_index);
>>> +       unsigned long sclk;
>>> +       int8_t clk_div;
>>> +
>>> +       /*
>>> +        * Since SDCLKIN is divided inside controller by the DIVRATIO
>>> +        * value set in the CLKSEL register, we need to use the same output
>>> +        * clock value to calculate the CLKDIV value.
>>> +        * as per user manual:cclk_in = SDCLKIN / (DIVRATIO + 1)
>>> +        */
>>> +       clk_div = ((dwmci_readl(host, DWMCI_CLKSEL) >> DWMCI_DIVRATIO_BIT)
>>> +                       & DWMCI_DIVRATIO_MASK) + 1;
I known DIVRATIO is only exynos5 feature..
And If clk_div is set to 0, then clk_phase/clk_strength is also set to 0.

And I think we can fixed this problem into exynos_dwmci_add_port.

Best Regards,
Jaehoon Chung

>>> +       sclk = get_mmc_clk(host->dev_index);
>>> +
>>> +       return sclk / clk_div;
>>>  }
>>>
>>>  /*
>>> diff --git a/include/dwmmc.h b/include/dwmmc.h
>>> index 08ced0b..26b53af 100644
>>> --- a/include/dwmmc.h
>>> +++ b/include/dwmmc.h
>>> @@ -138,7 +138,7 @@ struct dwmci_host {
>>>         struct mmc *mmc;
>>>
>>>         void (*clksel)(struct dwmci_host *host);
>>> -       unsigned int (*mmc_clk)(int dev_index);
>>> +       unsigned int (*mmc_clk)(struct dwmci_host *host);
>>>  };
>>>
>>>  struct dwmci_idmac {
>>> --
>>> 1.7.12.4
>>>
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>>
>>
>>
>> --
>> Regards,
>> Rajeshwari Shinde
> 
> 
>