On Sat, Jun 10, 2017 at 12:51:02AM +0800, Icenowy Zheng wrote: > > > 于 2017年6月10日 GMT+08:00 上午12:49:15, Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> 写到: > >On Wed, Jun 07, 2017 at 04:48:50PM +0800, Icenowy Zheng wrote: > >> >> @@ -189,6 +211,8 @@ supported. > >> >> Required properties: > >> >> - compatible: value must be one of: > >> >> * allwinner,sun8i-v3s-de2-mixer > >> >> + * allwinner,sun8i-h3-de2-mixer0 > >> >> + * allwinner,sun8i-h3-de2-mixer1 > >> > > >> >Again, please explain why we need to have different compatibles > >> >here. If it's only about the number of planes, this should be dealt > >> >with a property, not a compatible. > >> > >> Only mixer0 has "VEP" and write-back support, at least on H3. > > > >What is that VEP? writeback support can also be expressed by a > >property. > > I don't know what VEP is... Ok. Let's forget about it at the moment then, especially if it's optional, we can add support for it later. > But we are really facing different cores, like sun50i-a64-mmc > and sun50i-a64-emmc. Not really. The eMMC and MMC controllers are *very* different. They behave (slightly) differently, the eMMC controller has more signals (8-bit bus, data strobe), can run at a higher frequency. You cannot have exactly the same driver (or rather code path) to handle both. Therefore the need for some other compatible. This is not the case for the mixer here. The thing that differs between instances is not behaviour but data. And we provide most of the data through DT. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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