From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@bootlin.com (Maxime Ripard) Date: Tue, 27 Mar 2018 10:11:31 +0200 Subject: [linux-sunxi] Re: [PATCH 2/7] dt-bindings: add binding for the Allwinner A64 DE2 bus In-Reply-To: <9A6A8961-D45C-4033-962E-83CCE8F01651@aosc.io> References: <20180316175354.21437-1-icenowy@aosc.io> <20180320184646.dynqv6qubzabroe4@flea> <2866474.lRHIcLtROC@jernej-laptop> <9520BDDE-BFE3-4220-B48D-01A00CFA94DE@aosc.io> <20180326222258.uxpgj4bk4pg56b7o@rob-hp-laptop> <9A6A8961-D45C-4033-962E-83CCE8F01651@aosc.io> Message-ID: <20180327081131.hd652vkhohez2hcc@flea> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Mar 27, 2018 at 07:31:18AM +0800, Icenowy Zheng wrote: > > > ? 2018?3?27? GMT+08:00 ??6:22:58, Rob Herring ??: > >On Thu, Mar 22, 2018 at 02:08:43PM +0800, Icenowy Zheng wrote: > >> > >> > >> ? 2018?3?22? GMT+08:00 ??1:13:42, "Jernej ?krabec" > > ??: > >> >Hi all, > >> > > >> >Dne sreda, 21. marec 2018 ob 03:18:13 CET je Icenowy Zheng > >napisal(a): > >> >> ? 2018?3?21? GMT+08:00 ??2:46:46, Maxime Ripard > >> > > >> >??: > >> >> >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? We could have a single DT node that would export a syscon yes, just like you did for the R40 ethernet case. I'm not sure the SRAM controller itself needs to take the syscon, it just can export its own. Maxime -- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: