From: Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
To: zhangfei <zhangfei.gao-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Guodong Xu <guodong.xu-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
pawel.moll-5wv7dgnIgG8@public.gmane.org,
mark.rutland-5wv7dgnIgG8@public.gmane.org,
ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org,
galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org,
jh80.chung-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org,
ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org,
shawn.lin-NgiFYW8Wbx6Ta72+1OMJgUB+6BGkLq7r@public.gmane.org,
Xinwei Kong
<kong.kongxinwei-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org>
Subject: Re: [PATCH 2/2] mmc: dw_mmc: add resets support to dw_mci_parse_dt()
Date: Fri, 4 Mar 2016 11:45:57 +0800 [thread overview]
Message-ID: <56D904F5.9020700@rock-chips.com> (raw)
In-Reply-To: <56D900A8.9070204-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
在 2016/3/4 11:27, zhangfei 写道:
>
>
> On 03/03/2016 10:00 AM, Shawn Lin wrote:
>> Hi Guodong,
>>
>> On 2016/3/3 9:33, Guodong Xu wrote:
>>> With this, user can add a 'resets' property into dw_mmc dts
>>> node, and when driver probe and parse_dt, it will call
>>> reset APIs to reset dw_mmc host controller.
>>>
>>> Please also refer to Documentation/devicetree/bindings/reset/reset.txt
>>
>> I have no hard objection for this patch, but I'd rather not add it
>> unless we actually need it. Could you elaborate more about any futher
>> actions you will take if it's applied(i.e: deal with some unrecoverable
>> broken case)? If we just reset the controller while probing, actually I
>> can't find any problems without it based on tons of my reboot test.
>
> mmc register maybe abnormal state, if mmc is used in uefi, like boot
> from emmc.
> So we need reset mmc register when kernel boot up, instead of assuming
> mmc is in clean state.
> Next step is adding reset node in dts for drivers/mmc/host/dw_mmc-k3.c
> as reset driver is already there.
Fair enough. Thanks for explaining.
>
>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>> index 242f9a0..d3a7376 100644
>>> --- a/drivers/mmc/host/dw_mmc.c
>>> +++ b/drivers/mmc/host/dw_mmc.c
>>> @@ -2878,6 +2878,13 @@ static struct dw_mci_board
>>> *dw_mci_parse_dt(struct dw_mci *host)
>>> if (!pdata)
>>> return ERR_PTR(-ENOMEM);
>>>
>>> + /* find reset controller when exist */
>>> + pdata->rstc = devm_reset_control_get_optional(dev, NULL);
>>> + if (IS_ERR(pdata->rstc))
>>> + pdata->rstc = NULL;
>>> + else
>>> + reset_control_deassert(pdata->rstc);
>>> +
>>
>> if the PTR_ERR(pdata->rstc) is -EPROBE_DEFER, should we defer probing
>> the driver?
> Yes, good catch.
>
> Thanks
>
>
>
--
Best Regards
Shawn Lin
--
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next prev parent reply other threads:[~2016-03-04 3:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-03 1:33 [PATCH 1/2] Documentation: synopsys-dw-mshc: add binding for resets Guodong Xu
2016-03-03 1:33 ` [PATCH 2/2] mmc: dw_mmc: add resets support to dw_mci_parse_dt() Guodong Xu
2016-03-03 2:00 ` Shawn Lin
2016-03-04 3:27 ` zhangfei
[not found] ` <56D900A8.9070204-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2016-03-04 3:45 ` Shawn Lin [this message]
2016-03-05 4:28 ` [PATCH 1/2] Documentation: synopsys-dw-mshc: add binding for resets Rob Herring
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