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From: Rob Herring <robh@kernel.org>
To: Icenowy Zheng <icenowy@aosc.io>
Cc: jernej.skrabec@siol.net, linux-sunxi@googlegroups.com,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Chen-Yu Tsai <wens@csie.org>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org
Subject: Re: [linux-sunxi] Re: [PATCH 2/7] dt-bindings: add binding for the Allwinner A64 DE2 bus
Date: Mon, 26 Mar 2018 17:22:58 -0500	[thread overview]
Message-ID: <20180326222258.uxpgj4bk4pg56b7o@rob-hp-laptop> (raw)
In-Reply-To: <9520BDDE-BFE3-4220-B48D-01A00CFA94DE@aosc.io>

On Thu, Mar 22, 2018 at 02:08:43PM +0800, Icenowy Zheng wrote:
> 
> 
> 于 2018年3月22日 GMT+08:00 上午1:13:42, "Jernej Škrabec" <jernej.skrabec@siol.net> 写到:
> >Hi all,
> >
> >Dne sreda, 21. marec 2018 ob 03:18:13 CET je Icenowy Zheng napisal(a):
> >> 于 2018年3月21日 GMT+08:00 上午2:46:46, Maxime Ripard
> ><maxime.ripard@bootlin.com> 
> >写到:
> >> >On Sat, Mar 17, 2018 at 01:53:49AM +0800, Icenowy Zheng wrote:
> >> >> All the sub-blocks of Allwinner A64 DE2 needs the SRAM C on A64
> >SoC
> >> >
> >> >to
> >> >
> >> >> be claimed, otherwise the whole DE2 space is inaccessible.
> >> >> 
> >> >> Add a device tree binding of the DE2 part as a sub-bus.
> >> >
> >> >Where did you get the info that it was a bus?
> >> 
> >> There's no direct evidence, just some guess.
> >> 
> >> The DE2 is a whole part that is just allocated a memory
> >> space at the user manual, and the SRAM controls the
> >> access to all modules in the DE2.
> >> 
> >> So it might be a bus.
> >> 
> >> Implement it as a bus is a clear representation on A64.
> >
> >Since there is already syscon for same mmio region, we migh as well use
> >it 
> >when loading ccu-sun8i-de2 driver on A64.
> >
> >Other options, like SRAM driver or bus driver, might better represent
> >HW, but 
> 
> I think the device tree should properly represent the HW,
> it's a basic requirment.
> 
> >then we would have two DT nodes covering same mmio region, which I
> >think is 
> >not really acceptable.
> 
> It's acceptable, and DE2 is not the only user of SRAM controller so far.

No, it's not acceptable. Don't create overlapping mmio regions in DT.

> 
> VE will also need a SRAM region to be claimed.
> 
> >
> >Any suggestions?
> >
> >BTW, H6 has same design in this regard.
> >
> >Best regards,
> >Jernej
> --
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  reply	other threads:[~2018-03-26 22:23 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-16 17:53 [PATCH 0/7] Allwinner A64 DE2 CCU support with dedicated DE2 bus driver Icenowy Zheng
2018-03-16 17:53 ` [PATCH 1/7] dt-bindings: add compatible string for the A64 DE2 CCU Icenowy Zheng
2018-03-19 22:00   ` Stephen Boyd
2018-03-26 22:22   ` Rob Herring
2018-03-16 17:53 ` [PATCH 2/7] dt-bindings: add binding for the Allwinner A64 DE2 bus Icenowy Zheng
2018-03-20 18:46   ` Maxime Ripard
2018-03-21  2:18     ` Icenowy Zheng
2018-03-21 17:13       ` [linux-sunxi] " Jernej Škrabec
2018-03-22  6:08         ` Icenowy Zheng
2018-03-26 22:22           ` Rob Herring [this message]
2018-03-26 23:31             ` Icenowy Zheng
2018-03-27  8:11               ` Maxime Ripard
2018-03-16 17:53 ` [PATCH 3/7] bus: add bus driver for accessing Allwinner A64 DE2 Icenowy Zheng
2018-04-14 10:25   ` Jagan Teki
2018-04-14 10:30     ` Chen-Yu Tsai
2018-04-14 10:46       ` Jagan Teki
2018-04-19  6:35         ` Jagan Teki
2018-03-16 17:53 ` [PATCH 4/7] clk: sunxi-ng: add A64 compatible string Icenowy Zheng
2018-03-16 17:53 ` [PATCH 5/7] arm64: allwinner: a64: add DE2 CCU related device tree nodes Icenowy Zheng
2018-03-20 18:47   ` Maxime Ripard
2018-03-16 17:53 ` [PATCH 6/7] arm64: allwinner: a64: add simplefb for A64 SoC Icenowy Zheng
2018-03-16 17:53 ` [PATCH 7/7] arm64: allwinner: a64: add HDMI regulator to all DTs' simplefb_hdmi Icenowy Zheng

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