From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: Tegra DRM device tree bindings Date: Thu, 28 Jun 2012 10:46:58 -0600 Message-ID: <4FEC8A82.9090202@wwwdotorg.org> References: <20120626160224.40ba10a26e3dd3a56b1f312c@nvidia.com> <20120626140033.GC1115@avionic-0098.mockup.avionic-design.de> <23B010BBA481A74B98487467C29BA57BF2361DA3AA@HKMAIL01.nvidia.com> <4FEA6E09.30800@nvidia.com> <23B010BBA481A74B98487467C29BA57BF2361DA3C4@HKMAIL01.nvidia.com> <4FEA7472.7050201@nvidia.com> <20120627051418.GB7177@avionic-0098.mockup.avionic-design.de> <20120627155907.871b2a506374b7db14c202c4@nvidia.com> <20120627140809.GD19319@avionic-0098.mockup.avionic-design.de> <20120627172914.30a2ccfd1344161ca7724722@nvidia.com> <20120627144414.GA20681@avionic-0098.mockup.avionic-design.de> <20120628091853.d4c3d85749f9d41a5dfafd28@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120628091853.d4c3d85749f9d41a5dfafd28-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Hiroshi Doyu Cc: Thierry Reding , Stephen Warren , Mark Zhang , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , Lucas Stach List-Id: devicetree@vger.kernel.org On 06/28/2012 12:18 AM, Hiroshi Doyu wrote: > On Wed, 27 Jun 2012 16:44:14 +0200 > Thierry Reding wrote: > >>> I think that "coherent_pool" can be used only when the amount of >>> contiguous memory is short in your system. Otherwise even unnecessary. >>> >>> Could you explain a bit more why you want carveout size on per-board basis? >> >> In the ideal case I would want to not have a carveout size at all. >> However there may be situations where you need to make sure some driver >> can allocate a given amount of memory. Having to specify this using a >> kernel command-line parameter is cumbersome because it may require >> changes to the bootloader or whatever. So if you know that a particular >> board always needs 128 MiB of carveout, then it makes sense to specify >> it on a per-board basis. > > Hm...I could understand somewhat;) but DT can also specify "bootargs" > in dts file, which can support per-board-wide spec too, like the above > sum of carveout needed from all drivers. I just want to avoid > introducing a new parameter additionaly if we can make use of the > existing mechanism. The bootargs in the DT file is usually provided by (over-written by) the bootloader. If we start requiring lots of random kernel command-line arguments, that makes it more effort for the user of the bootloader (e.g. distribution bootloader scripts, etc.) to create the kernel command-line. I'd prefer to avoid that as much as possible. That said, using a standardized command-line option that is (or will be) used by all (ARM?) SoCs for the same purpose is reasonable, because there's commonality there.