From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Figa Subject: Re: [PATCH 1/3] clk: exynos5420: Add 5800 specific clocks Date: Sat, 03 May 2014 04:12:15 +0200 Message-ID: <5364507F.90400@gmail.com> References: <1399035821-25096-1-git-send-email-arun.kk@samsung.com> <1399035821-25096-2-git-send-email-arun.kk@samsung.com> <4431329.kolHX05ZMV@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-qa0-f46.google.com ([209.85.216.46]:50317 "EHLO mail-qa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751640AbaECCMQ (ORCPT ); Fri, 2 May 2014 22:12:16 -0400 In-Reply-To: Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Doug Anderson , Arnd Bergmann Cc: Arun Kumar K , linux-samsung-soc , "devicetree@vger.kernel.org" , Kukjin Kim , Olof Johansson , Tomasz Figa , Sachin Kamat , Tushar Behera , Arun Kumar , Andrew Bresticker On 02.05.2014 21:35, Doug Anderson wrote: > Arnd, > > On Fri, May 2, 2014 at 11:52 AM, Arnd Bergmann wrote: >> On Friday 02 May 2014 18:33:39 Arun Kumar K wrote: >>> From: Alim Akhtar >>> >>> Exynos5800 clock structure is mostly similar to 5420 with only >>> a small delta changes. So the 5420 clock file is re-used for >>> 5800 also. The common clocks for both are seggreagated and few >>> clocks which are different for both are separately initialized. >>> >>> Signed-off-by: Alim Akhtar >>> Signed-off-by: Arun Kumar K >> >> This isn't about your specific patch, but every time I see a new >> exynos variant get supported, it comes with a clock driver patch >> that is at least as big as all the other patches combined. >> >> New variants come out all the time now, and we are starting to >> accumulate huge amounts of clock definitions both in the source >> and the binary. I think we should try to come up with a better >> way to represent the clocks. I don't think any other SoC >> family is nearly as bad as Exynos, either because they have >> much fewer models, or because they abstract their clocks more >> and put all the tables into DT. >> >> I'm definitely not saying no to the exynos5800 addition for this, >> but I'm starting to get a little annoyed, and I think it would be >> good to come up with a new clock binding before we see 64-bit >> Exynos variants. > > One thing to note: your suggestion will almost certainly not be > conducive to get stable device trees. IMHO there's pretty much a zero > chance that you could properly describe all of the exynos clocks in > the first, second, third, or twentieth attempt. That means that if > anyone ever took it in their head to actually ship a device tree that > wasn't bundled with the kernel that it would probably be wrong. > > Declaring just "I have exynos5800 clocks" means that you're not > relying on the device tree. > > > The clocks are pretty table-based as-is, and I think that's about the > best you're going to get. +1 and similarly to pinctrl stuff. Both full-DT and table-based approaches were being discussed long time ago when moving Exynos to DT and generic frameworks and the conclusion was clearly in favor of the latter. Moreover, I don't think we should really be concerned about this, because we already have far less changes (not counting device tree sources) needed to support a SoC than we had before, in board file times. Not even saying that new SoCs are not being added that often. > > > NOTE: one could argue that possibly the 5420 and 5800 are different > enough that they ought to have separate tables. I don't feel like I'm > in enough of an ownership position to make that tradeoff either way, > though. I don't have the datasheets, but looking at the changes needed, they don't seem to be more different than Exynos4210 and Exynos4x12. The approach taken looks fine for me. Best regards, Tomasz