Re: [v4,1/4] dt-binding: reset-controller: ti: add reset-duration-us property

From: Crystal Guo <crystal.guo@mediatek.com>
To: Rob Herring <robh@kernel.org>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"Yong Liang (梁勇)" <Yong.Liang@mediatek.com>,
	"Stanley Chu (朱原陞)" <stanley.chu@mediatek.com>,
	srv_heupstream <srv_heupstream@mediatek.com>,
	"Seiya Wang (王迺君)" <seiya.wang@mediatek.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"afd@ti.com" <afd@ti.com>,
	"Fan Chen (陳凡)" <fan.chen@mediatek.com>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"Yingjoe Chen (陳英洲)" <Yingjoe.Chen@mediatek.com>,
	"s-anna@ti.com" <s-anna@ti.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [v4,1/4] dt-binding: reset-controller: ti: add reset-duration-us property
Date: Wed, 26 Aug 2020 19:09:19 +0800	[thread overview]
Message-ID: <1598440159.30048.13.camel@mhfsdcap03> (raw)
In-Reply-To: <20200825174215.GA999117@bogus>

On Wed, 2020-08-26 at 01:42 +0800, Rob Herring wrote:
> On Mon, Aug 17, 2020 at 11:03:21AM +0800, Crystal Guo wrote:
> > introduce 'reset' method to allow device do serialized assert and
> > deassert operations in a single step, which needs a minimum delay
> > to be waited between assert and deassert.
> 
> Why is Mediatek adding to a TI binding?

TI reset-controller provides a common reset management,
and is suitable for Mediatek SoCs, thus Mediatek wants to reuse this
driver for reset.

> 
> > 
> > Signed-off-by: Crystal Guo <crystal.guo@mediatek.com>
> > ---
> >  Documentation/devicetree/bindings/reset/ti-syscon-reset.txt | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt b/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
> > index 86945502ccb5..ab041032339b 100644
> > --- a/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
> > +++ b/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
> > @@ -59,6 +59,11 @@ Required properties:
> >  Please also refer to Documentation/devicetree/bindings/reset/reset.txt for
> >  common reset controller usage by consumers.
> >  
> > +Optional properties:
> > +- reset-duration-us: When do serialized assert and deassert operations, minimum delay in microseconds
> > +is needed to be waited between an assert and a deassert to reset the device. This value can be 0, 0 means
> > +that such a delay is not needed.
> 
> This goes in the reset controller node or each consumer? For the latter, 
> it should be a cell in 'resets' if you need this. But really, I think 
> the reset controller should enforce some minimum time that works for all 
> consumers. Surely having a minimum time per reset isn't really needed.
> 
> Rob

'reset-duration-us' will be in the reset controller node, and it's
optional. If minimum delay is needed to be waited between an assert and
a deassert to reset the device, this property will be set.Otherwise no
need to set this property.

Best Regards
Crystal

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