Re: [PATCH 1/2] Documentation: synopsys-dw-mshc: add binding for resets

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi Shawn,

On 03/07/2016 06:35 PM, Shawn Lin wrote:
> Hi Jaehoon,
> 
> On 2016/3/7 8:53, Jaehoon Chung wrote:
>> Hi Goudong,
>>
>> On 03/06/2016 05:47 PM, Guodong Xu wrote:
>>> Add resets property to synopsys-dw-mshc bindings. It is intended to
>>> represent the hardware reset signal present internally in some host
>>> controller IC designs.
>>>
>>> See Documentation/devicetree/bindings/reset/reset.txt for details.
>>>
>>> Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
>>> Acked-by: Rob Herring <robh@kernel.org>
>>> ---
>>>   Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt | 4 ++++
>>>   1 file changed, 4 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt
>>> index 8636f5a..4e00e85 100644
>>> --- a/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt
>>> +++ b/Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt
>>> @@ -39,6 +39,10 @@ Required Properties:
>>>
>>>   Optional properties:
>>>
>>> +* resets: phandle + reset specifier pair, intended to represent hardware
>>> +  reset signal present internally in some host controller IC designs.
>>> +  See Documentation/devicetree/bindings/reset/reset.txt for details.
>>
>> Is this reset property for common dwmmc IP controller?
> 
> I think so. By discussion with my ASIC team, it's provided by synopsys.
> From dw_mmc databook version 270a, section 3.2.5, FBE Scenarios:
> 
> An FBE occurs due to an AHB error response on the AHB bus. This is a
> system error, so the software driver should not perform any further
> programming to the DWC_mobile_storage. The only recovery mechanism
> from such scenarios is to do one of the following:
> ■ Issue a hard reset by asserting the reset_n signal
> ■ Do a program controller reset by writing to the CTRL[0] register
> 
> the reset_n signal can be used to reset all the internal logic block
> with dwmmc and reset the register value to default stat.
> 
> Note: reset_n is a internal signal, which is diff from rst_n for mmc hw
> reset. (refer to databook section 5.2 Signal Descriptions, table 5-1)

Thanks for this information. :)

> 
>>
>> Best Regards,
>> Jaehoon Chung
>>
>>> +
>>>   * clocks: from common clock binding: handle to biu and ciu clocks for the
>>>     bus interface unit clock and the card interface unit clock.
>>>
>>>
>>
>>
>>
>>
> 
>