From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Wed, 1 Oct 2014 10:27:05 +0200 Subject: [PATCH 7/9] dmaengine: Move slave caps to dma_device In-Reply-To: <20140927092846.GA5182@n2100.arm.linux.org.uk> References: <1411808085-27792-1-git-send-email-maxime.ripard@free-electrons.com> <1411808085-27792-8-git-send-email-maxime.ripard@free-electrons.com> <20140927092846.GA5182@n2100.arm.linux.org.uk> Message-ID: <20141001082705.GF6884@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Sep 27, 2014 at 10:28:47AM +0100, Russell King - ARM Linux wrote: > On Sat, Sep 27, 2014 at 10:54:43AM +0200, Maxime Ripard wrote: > > The previous code was relying on the fact that the slave_caps were to be > > defined on a per channel basis. > > > > However, this proved to be a bit overkill, since every driver filling these so > > far were hardcoding it, disregarding which channel was actually given. > > > > Add these capabilities to the dma_device structure, so that drivers can just > > provide them at probe time, and be done with it. > > This is also buggy for the same reason as patch 6. Indeed > The only way to do this is to either have a flag day, fixing all drivers > at once (which isn't going to happen) or leave the caps code as-is, and > provide a library function which drivers can hook into the caps callback > which retrieves the information from dma_device. > > That way, DMA engine drivers which are using the new method can just > install the new function, and those which haven't been updated with > capabilities can carry on as they are, and are detectable to drivers. Which is pretty much the current behaviour, isn't it? > What would be acceptable is to have the DMA engine registration function > spot the lack of DMA caps function and print a warning at boot to > encourage people to add it. That would be an option too. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: