From mboxrd@z Thu Jan 1 00:00:00 1970 From: dwmw2@infradead.org (David Woodhouse) Date: Thu, 24 Oct 2013 13:14:38 -0000 Subject: [Ksummit-2013-discuss] ARM topic: Is DT on ARM the solution, or is there something better? In-Reply-To: <1382619952.6040.57.camel@sakura.staff.proxad.net> References: <20131020220839.GT2443@sirena.org.uk> <5264576F.6050307@wwwdotorg.org> <52658EBC.8020800@wwwdotorg.org> <20131022093923.GC15640@ulmo.nvidia.com> <20131022150426.GF29341@beef> <20131022171346.GE4061@obsidianresearch.com> <20131023080630.GA14413@netboy> <20131023172955.GA17145@obsidianresearch.com> <20131023174458.GC5208@netboy> <1382553982.31058.10.camel@sakura.staff.proxad.net> <20131024095232.27BBCC4039D@trevor.secretlab.ca> <1382614439.6040.16.camel@sakura.staff.proxad.net> <1382615278.8522.72.camel@shinybook.infradead.org> <1382616801.6040.26.camel@sakura.staff.proxad.net> <3726fd81259f84ef308ba9011ae35174.squirrel@twosheds.infradead.org> <1382619952.6040.57.camel@sakura.staff.proxad.net> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > > On Thu, 2013-10-24 at 12:22 +0000, David Woodhouse wrote: > >> If you are correct to insist that DMA needs yo be supported in the new >> driver *even* with old firmware, then yes, maybe. > > if DMA gives a performance boost for all workloads, what is the argument > for not always enabling it ? If DMA gives a performance boost for all workloads, what bloody idiot defined or reviewed a DT binding that didn't include the information which is required to uae DMA? :) >> The alternative is a quirk to "fix" the DT up on the affected boards and >> not actually doing the special cases in the driver itself. But that can >> be >> seen as an implementation detail. > > I don't understand why having the soc-foo.h with the internal interrupt > mapping in the kernel tree is a no-no, whereas it's ok to add the > missing part of it in the form of fixups or directly in driver code. It's the difference between doing it as a matter of course, and doing it only in the very rare "OMG we fucked up but we really *need* to fix it up this time" case. -- dwmw2