From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benoit Cousson Subject: Re: [PATCH 5/9] ARM: dts: Add GPMC node for OMAP2, OMAP4 and OMAP5 Date: Thu, 14 Mar 2013 17:03:55 +0100 Message-ID: <5141F4EB.4050807@ti.com> References: <1362763654-9660-1-git-send-email-jon-hunter@ti.com> <1362763654-9660-6-git-send-email-jon-hunter@ti.com> <513A5B23.5070302@ti.com> <513E1ADC.6030208@ti.com> <5141F07E.3030501@ti.com> <5141F1C3.6090009@ti.com> <5141F3B9.4090103@ti.com> <5141F43B.5010702@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:33186 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932738Ab3CNQEP (ORCPT ); Thu, 14 Mar 2013 12:04:15 -0400 In-Reply-To: <5141F43B.5010702@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Jon Hunter Cc: Ezequiel Garcia , Javier Martinez Canillas , Tony Lindgren , device-tree , linux-omap , linux-arm On 03/14/2013 05:00 PM, Jon Hunter wrote: > > > On 03/14/2013 10:58 AM, Benoit Cousson wrote: >> On 03/14/2013 04:50 PM, Jon Hunter wrote: >>> >>> On 03/14/2013 10:45 AM, Benoit Cousson wrote: >>>> On 03/11/2013 06:56 PM, Jon Hunter wrote: >>>>> >>>>> On 03/09/2013 06:42 AM, Ezequiel Garcia wrote: >>>>>> On Fri, Mar 8, 2013 at 10:25 PM, Javier Martinez Canillas >>>>>> wrote: >>>>>>> On Fri, Mar 8, 2013 at 10:41 PM, Jon Hunter wrote: >>>>>>>> >>>>>>>> Yes you are correct. In general, I have been trying to stay some-what >>>>>>>> consistent with what hwmod was doing as this was being auto-generated by >>>>>>>> some hardware design specs and I believe they wanted to eventually get >>>>>>>> to the point where DT files would be auto-generated too for OMAP. >>>>>>>> Furthermore my understanding is that the smallest page that can be >>>>>>>> mapped by the kernel for ARM is 4kB. So if you declare it as 0x2d0 or >>>>>>>> 0x1000 it will map a 4kB page (I could be wrong here). >>>>>>>> >>>>>>>> I don't have any strong feelings here but will do what the consensus >>>>>>>> prefers. >>>>>>>> >>>>>>> >>>>>>> Yes, you are right here. >>>>>>> >>>>>>> I forget that ioremap() does a page-aligned mapping and since the >>>>>>> minimum page size for ARM is 4KB as you said, there is no difference >>>>>>> between using 0x2d0 and 0x1000. Sorry for the noise. >>>>>>> >>>>>> >>>>>> Certainly, I don't have strong feelings about this. >>>>>> FWIW, mvebu maintainers imposes a "minimal" address space request >>>>>> policy. >>>>>> >>>>>> On the other side, it seems to me we shouldn't look at internal kernel >>>>>> implementation (i.e. ioremap page-alignment) to make this decision. >>>>> >>>>> I agree with that. I am not sure if Tony/Benoit have any comments on >>>>> what they would like to do here to be consistent for the omap bindings. >>>> >>>> Yes, I full agree with that as well. The size should be purely HW >>>> related. So we should not take any assumption about the page size / >>>> alignment. >>> >>> Ok, what is best to use? The size from hwmod structures or the size from >>> the documentation? >> >> Well, in theory both are supposed to be identical :-) >> I'm just applying a rounding to the closet power of two, that's why it >> cannot be 0x2d0. > > Ok I understand. However, still not clear what you want me to use :-( That's on purpose :-) Take 0x2d0, we could always remove the rounding in the generation part to stick to the HW documentation. Regards Benoit