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From: Icenowy Zheng <icenowy@aosc.io>
To: linux-arm-kernel@lists.infradead.org, Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org, jernej.skrabec@siol.net,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	linux-sunxi@googlegroups.com, linux-kernel@vger.kernel.org,
	Chen-Yu Tsai <wens@csie.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: Tue, 27 Mar 2018 07:31:18 +0800	[thread overview]
Message-ID: <9A6A8961-D45C-4033-962E-83CCE8F01651@aosc.io> (raw)
In-Reply-To: <20180326222258.uxpgj4bk4pg56b7o@rob-hp-laptop>



于 2018年3月27日 GMT+08:00 上午6:22:58, Rob Herring <robh@kernel.org> 写到:
>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.

Then should the SRAM controller driver be configured to take the syscon?

>
>> 
>> VE will also need a SRAM region to be claimed.
>> 
>> >
>> >Any suggestions?
>> >
>> >BTW, H6 has same design in this regard.
>> >
>> >Best regards,
>> >Jernej
>> --
>> To unsubscribe from this list: send the line "unsubscribe devicetree"
>in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>_______________________________________________
>linux-arm-kernel mailing list
>linux-arm-kernel@lists.infradead.org
>http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2018-03-26 23:31 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
2018-03-26 23:31             ` Icenowy Zheng [this message]
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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