[U-Boot] [PATCH] MMC: DWMMC: Fix FIFO_DEPTH calculation

[Jaehoon Chung]

Hi Jagan,

On 05/24/2013 03:15 PM, Rajeshwari Birje wrote:
> Hi Jagan,
> 
> Please find my comments below.
> On Fri, May 24, 2013 at 10:31 AM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>> On Fri, May 24, 2013 at 7:12 AM, Jaehoon Chung <jh80.chung at samsung.com> wrote:
>>> On 05/24/2013 03:27 AM, Jagan Teki wrote:
>>>> On Thu, May 23, 2013 at 6:45 PM, Rajeshwari Shinde
>>>> <rajeshwari.s at samsung.com> wrote:
>>>>> Current DWMMC driver used to give FIFO underrun/overrun error every 3rd time
>>>>> for mmc rescan command.
>>>>> In current code FIFO_DEPTH is getting calculated after reading the FIFOTH
>>>>> register and extracting the RX_WMARK bits from it i.e (RX_WMARK = FIFO_DEPTH/2 -1).
>>>>> Instead of storing the correct value, we were recalculating the FIFO_DEPT each
>>>>> time which is not correct.
>>>>>
>>>>> Signed-off-by: Hatim Ali <hatim.rv at samsung.com>
>>>>> Signed-off-by: Rajeshwari Shinde <rajeshwari.s at samsung.com>
>>>>> ---
>>>>>  drivers/mmc/dw_mmc.c |    6 ++++--
>>>>>  1 files changed, 4 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
>>>>> index 4070d4e..be590a4 100644
>>>>> --- a/drivers/mmc/dw_mmc.c
>>>>> +++ b/drivers/mmc/dw_mmc.c
>>>>> @@ -332,11 +332,13 @@ static int dwmci_init(struct mmc *mmc)
>>>>>         dwmci_writel(host, DWMCI_BMOD, 1);
>>>>>
>>>>>         fifo_size = dwmci_readl(host, DWMCI_FIFOTH);
>>>>> -       if (host->fifoth_val)
>>>>> +       if (host->fifoth_val) {
>>>>
>>>> What is the inital value for host->fifoth_val, for the first time call.?
>>> It should be set into board-specific file(dw-mmc_exynos.c) or others.
>>
>> I am unable to find dw-mmc_exynos.c on the master, and also I haven't
>> see fifoth_val used other than dw_mmc.c
>> Could you please help me out.
> dw-mmc_exynos.c is merged in mmc tree. Yes  FIFO_DEPTH is set only in dw_mmc.c
host->fifoth_val should be set to hard-coding by developer.
In general case, it's right that fifoth_Val is calculated with register value.
But sometime, it needs to set to other value, not register value. 
Then we can use the host->fifoth_val in board-specific file.
Maybe it didn't use the host->fifoth_val anywhere. In future, we can use this.

Best Regards,
Jaehoon Chung
>>
>> Thanks,
>> Jagan.
>>
>>>
>>> Best Regards,
>>> Jaehoon Chung
>>>>
>>>>>                 fifoth_val = host->fifoth_val;
>>>>> -       else
>>>>> +       } else {
>>>>>                 fifoth_val = MSIZE(0x2) | RX_WMARK(fifo_size/2 -1) |
>>>>>                         TX_WMARK(fifo_size/2);
>>>>> +               host->fifoth_val = fifoth_val;
>>>>> +       }
>>>>>         dwmci_writel(host, DWMCI_FIFOTH, fifoth_val);
>>>>>
>>>>>         dwmci_writel(host, DWMCI_CLKENA, 0);
>>>>> --
>>>>> 1.7.4.4
>>>>>
>>>>
>>>> Thanks,
>>>> Jagan.
>>>>
>>>
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>