[U-Boot] [PATCH 1/3] samsung: board: support eMMC reset using DT

[Joonyoung Shim <jy0922.shim@samsung.com>]

On 01/09/2015 08:13 PM, Jaehoon Chung wrote:
> On 01/09/2015 04:31 PM, Joonyoung Shim wrote:
>> +Cc Jaehoon,
>>
>> On 01/09/2015 03:18 AM, Simon Glass wrote:
>>> Hi Joonyoung,
>>>
>>> On 7 January 2015 at 22:44, Joonyoung Shim <jy0922.shim@samsung.com> wrote:
>>>> Some exynos boards require special handling of SD4_nRESET_OUT line for
>>>> eMMC memory to perform complete reboot e.g. Odroid X2/U3/XU3 boards.
>>>>
>>>> This will support eMMC reset using DT from reset_misc of samsung common
>>>> board file and each board files can support eMMC reset on non DT case.
>>>>
>>>> Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
>>>> ---
>>>>  board/samsung/common/board.c                   | 27 ++++++++++++++++++++++++++
>>>>  board/samsung/odroid/odroid.c                  |  2 +-
>>>>  doc/device-tree-bindings/exynos/emmc-reset.txt | 15 ++++++++++++++
>>>>  3 files changed, 43 insertions(+), 1 deletion(-)
>>>>  create mode 100644 doc/device-tree-bindings/exynos/emmc-reset.txt
>>>>
>>>> diff --git a/board/samsung/common/board.c b/board/samsung/common/board.c
>>>> index c04ab3c..3218463 100644
>>>> --- a/board/samsung/common/board.c
>>>> +++ b/board/samsung/common/board.c
>>>> @@ -40,6 +40,8 @@ __weak int exynos_power_init(void)
>>>>         return 0;
>>>>  }
>>>>
>>>> +__weak void exynos_reset_misc(void) {}
>>>> +
>>>>  #if defined CONFIG_EXYNOS_TMU
>>>>  /* Boot Time Thermal Analysis for SoC temperature threshold breach */
>>>>  static void boot_temp_check(void)
>>>> @@ -400,3 +402,28 @@ int misc_init_r(void)
>>>>         return 0;
>>>>  }
>>>>  #endif
>>>> +
>>>> +void reset_misc(void)
>>>> +{
>>>> +#ifdef CONFIG_OF_CONTROL
>>>
>>> I think all Samsung boards have this defined, so this #ifdef can be removed.
>>>
>>
>> OK, if it is true, we can remove this and i will not to support non DT case.
>>
>>>> +       struct gpio_desc gpio = {};
>>>> +       int node;
>>>> +
>>>> +       node = fdt_node_offset_by_compatible(gd->fdt_blob, 0,
>>>> +                       "samsung,emmc-reset");
>>>> +       if (node < 0)
>>>> +               return;
>>>> +
>>>> +       gpio_request_by_name_nodev(gd->fdt_blob, node, "reset-gpio", 0, &gpio,
>>>> +                                  GPIOD_IS_OUT);
>>>> +
>>>> +       if (dm_gpio_is_valid(&gpio)) {
>>>> +               /* Reset eMMC*/
>>>> +               dm_gpio_set_value(&gpio, 0);
>>>> +               mdelay(10);
>>>
>>> That's a very long reset! Is that what it needs?
>>>
>>
>> Jaehoon, is there any guide about wait time of reset at eMMC spec?
> 
> Well, I'm not sure, but as Simon's comments, it's long time.
> (Minimum is 1us...Maximum isn't defined.)
> 

This just comes from reset_misc() of board/samsung/odroid/odroid.c file.
Even, hardkernel u-boot waits 50msec.

Thanks.