From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Thu, 22 Sep 2011 14:13:02 +0100 Subject: DT vs ARM static mappings In-Reply-To: <1316696696.4611.844.camel@hornet.cambridge.arm.com> References: <1316519479.4611.150.camel@hornet.cambridge.arm.com> <1316696696.4611.844.camel@hornet.cambridge.arm.com> Message-ID: <20110922131302.GO17169@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Sep 22, 2011 at 02:04:56PM +0100, Pawel Moll wrote: > > > ARM machine description contains a "map_io" method, which is used to > > > create static memory mappings (using iotable_init() function) for things > > > like peripherals or SRAMs. At least that's the theory, because most of > > > the platforms are doing much more stuff there, like clocking/GPIOs/UARTs > > > initialization, hardware probing etc. > > > > No, most of them don't. Maybe a few cases do for historical reasons, > > but there are other hooks now to link probing and initialization code > > to. > > Ok, what I did was grepping for all .map_io-s. Then I sorted the list > and had a look at first 100 and about 50% of them were doing more than > just creating mappings. The answer to that is: they shouldn't be now that we have the init_early hook. The only remainder for .map_io is where platforms make run-time decisions about what to map based on some register value somewhere (eg, Assabet vs Assabet+Neponset). I do have a large patch series floating around in my git tree which tries to clean up to all those map_io functions - the biggest stumbling block to them is the Samsung stuff being indirected through its own tables. Of course, with all the changes to .boot_params etc, the patches no longer apply to current kernels.