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Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc

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On 04/02/2016 03:42 AM, Heiko Stuebner wrote:
> Am Mittwoch, 30. März 2016, 20:40:31 schrieb Jaehoon Chung:
>> modified Rob's mail address.
>>
>> On 03/30/2016 04:24 PM, Guodong Xu wrote:
>>> mmc registers may in abnormal state if mmc is used in bootloader,
>>> eg. to support booting from eMMC. So we need reset mmc registers
>>> when kernel boots up, instead of assuming mmc is in clean state.
>>
>> Do you mean mmc(card side) register or dwmmc host controller's register on
>> host side?
>>
>> According to dwmmc controller TMR, there are two reset signals. One is
>> reset_n, other is rst_n. It seems this patch is relevant to reset_n(For
>> host). (rst_n is hardware reset for card.)
>>
>> So could you clarify better? Then it's helpful to me for understanding..
> 
> I think that actually means a reset of controller IP block logic, outside 
> the control of the dw_mmc block itself.
> 
> On Rockchip SoCs this gets triggered from the CRU (clock and reset unit), so 
> I guess if I'm reading the manual correctly, should be the reset_n signal of 
> the ip block.
> 
> rst_n on the other hand gets triggered through a dw_mmc register setting and 
> is already handled by the dw_mmc driver.

Right, this patch is for reset_n signal. I didn't have seen the SoC that reset_n is designed.
(Or i didn't realize...)
If Rockchip is used from CRU (clock and reset unit), then i think that it makes sense.

Thanks for explanation. 

Best Regards,
Jaehoon Chung

> 
> 
> Heiko
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[PATCH v3 0/2] mmc: dw_mmc: controller reset support Guodong Xu <guodong.xu@linaro.org> - 2016-03-30 09:30 +0200
  [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Guodong Xu <guodong.xu@linaro.org> - 2016-03-30 09:30 +0200
    Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Jaehoon Chung <jh80.chung@samsung.com> - 2016-03-30 13:50 +0200
      Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Heiko Stuebner <heiko@sntech.de> - 2016-04-01 20:50 +0200
        Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Jaehoon Chung <jh80.chung@samsung.com> - 2016-04-04 06:00 +0200
    Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Heiko Stuebner <heiko@sntech.de> - 2016-04-01 20:50 +0200
      Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Heiko Stuebner <heiko@sntech.de> - 2016-04-02 16:10 +0200
  [PATCH v3 1/2] Documentation: synopsys-dw-mshc: add binding for resets Guodong Xu <guodong.xu@linaro.org> - 2016-03-30 09:30 +0200
  Re: [PATCH v3 0/2] mmc: dw_mmc: controller reset support Shawn Lin <shawn.lin@rock-chips.com> - 2016-03-30 13:50 +0200

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