From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 0/3] mmc: omap_hsmmc: get rid of ti,non-removable Date: Wed, 18 Sep 2013 11:58:19 -0700 Message-ID: <20130918185818.GC9994@atomide.com> References: <20130913153732.GO7189@atomide.com> <5236F8BC.1000305@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <5236F8BC.1000305@ti.com> Sender: linux-mmc-owner@vger.kernel.org To: Sekhar Nori Cc: Chris Ball , Benoit Cousson , Grant Likely , Rob Herring , Device Tree Mailing List , Linux OMAP Mailing List , Koen Kooi , Linux MMC Mailing List List-Id: devicetree@vger.kernel.org * Sekhar Nori [130916 05:33]: > On Friday 13 September 2013 09:07 PM, Tony Lindgren wrote: > > * Sekhar Nori [130913 03:18]: > >> Get rid of TI specific binding ti,non-removable in favour of the > >> generic binding present for the same purpose. > > > > Looks like there's a different handling in the MMC driver > > for no_regulator_off_init that's needed for eMMC. That needs to > > be sorted out and tested first. > > Okay. I couldn't really get the eMMC on my board to detect, but > apparently Koen has been able to get it to work. I am not really deep > into details of HSMMC driver so will check with Balaji on what needs to > be done here. I think the issue is that until we have a SCM driver module setting up the PBIAS register as a regulator, eMMC cards won't work without ti,non-removable. > >> This patch set does not support the old binding anymore. So, yes, > >> it does introduce an ABI breakage. IMHO, it is not really worth > >> supporting both bindings ATM since DT-usage in OMAP is still very > >> nascent and almost always DTB and uImage are upgraded together. > > > > The old bindings must be supported. It's not like we can just drop > > them. We should just keep the old binding and parse it the same way > > as the generic binding. That's a minimal amount of code. > > Yes, its minimal amount of code but its code that will very likely never > get exercised in future because of the reasons I mentioned above. I fear > in time we will accumulate a lot of unused code this way. Hey it's an ABI :) > Anyway, since you don't feel its okay to remove the old binding, I will > go ahead and mark the old binding as deprecated. But perhaps we can > come-up with some time frame within which users of old .dtb can upgrade > their .dtb or consider never upgrading to a newer kernel? This sounds > eerily similar to feature-removal-schedule.txt and yeah I am aware of > what happened to that. But I still put it here since this problem of DTB > compatibility is not going to go away. But before doing that, we first must fix the issue for still needing ti,non-removable. > One thing that might help is a kernel configuration that does not > support deprecated bindings so users of old dtbs can actually see what > deprecated bindings they are using. This way they can probably plan for > a dtb upgrade better. So in driver you would do something like: > > if (of_support_deprecated_bindings() && > of_find_property(np, "ti,non-removable", NULL)) { > .. do something .. > } > > of_support_deprecated_bindings() would return based on a config option. Hmm yeah maybe that should be discussed separately on the device tree mailing list. Regards, Tony