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

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Message-ID: <56DD4B79.2090509@rock-chips.com>
Date:	Mon, 7 Mar 2016 17:35:53 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Jaehoon Chung <jh80.chung@...sung.com>,
	Guodong Xu <guodong.xu@...aro.org>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	ulf.hansson@...aro.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org
Cc:	shawn.lin@...k-chips.com, shawn.lin@...nel-upstream.org
Subject: Re: [PATCH 1/2] Documentation: synopsys-dw-mshc: add binding for
 resets

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@...aro.org>
>> Acked-by: Rob Herring <robh@...nel.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)

>
> 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.
>>
>>
>
>
>
>


-- 
Best Regards
Shawn Lin