From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.free-electrons.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cPQDg-0002zJ-1x for linux-mtd@lists.infradead.org; Fri, 06 Jan 2017 08:49:53 +0000 Date: Fri, 6 Jan 2017 09:49:30 +0100 From: Boris Brezillon To: =?UTF-8?B?Q8OpZHJpYw==?= Le Goater Cc: Cyrille Pitchen , Cyrille Pitchen , linux-mtd@lists.infradead.org, Mark Rutland , devicetree@vger.kernel.org, Richard Weinberger , Marek Vasut , Rob Herring , Joel Stanley , Brian Norris , David Woodhouse Subject: Re: [PATCH v4 1/4] mtd: spi-nor: add memory controllers for the Aspeed AST2500 SoC Message-ID: <20170106094930.0f579dca@bbrezillon> In-Reply-To: <4c0b4498-12c7-303d-c8f8-4f27a02d6c12@kaod.org> References: <1481557252-13656-1-git-send-email-clg@kaod.org> <1481557252-13656-2-git-send-email-clg@kaod.org> <5566c62d-cc72-f207-e1dd-5a59e6947c24@wedev4u.fr> <2bec1e91-a196-b894-fb66-590b8f4f35c3@atmel.com> <645db8c4-7f3c-f8bf-ddd9-3f513ce2ed14@kaod.org> <4c5cf674-06f9-ad6b-05bf-a1d39aaa7ed5@atmel.com> <20170104185005.7fcafd2d@bbrezillon> <4c0b4498-12c7-303d-c8f8-4f27a02d6c12@kaod.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi C=C3=A9dric, On Thu, 5 Jan 2017 14:39:14 +0100 C=C3=A9dric Le Goater wrote: > Hello Cyrille, Boris=20 >=20 > On 01/04/2017 06:50 PM, Boris Brezillon wrote: > > Cyrille, C=C3=A9dric, > >=20 > > On Wed, 4 Jan 2017 15:52:07 +0100 > > Cyrille Pitchen wrote: > > =20 > >>> =20 > >>>> Anyway, since the review is done now, on my side I won't ask you to = remove > >>>> or split the support of the 'Command' mode in a separated patch. > >>>> I let you do as you want, if it help you to introduce some part of t= he > >>>> support of this 'Command' mode now even if not completed yet, no pro= blem on > >>>> my side :) > >>>> > >>>> I was just giving you some pieces of advice for the next time if you= want > >>>> to speed up the review of another patch introducing new features. > >>>> > >>>> However, I will just ask you one more version handling the dummy cyc= les > >>>> properly as it would help us for the global maintenance of the spi-n= or > >>>> subsystem. This is the only mandatory modification I ask you, after = that I > >>>> think it would be ok for me and since Marek has already reviewed your > >>>> driver, it would be ready to be merged into the spi-nor tree. =20 > >>> > >>> Sending a v5 which should address your comments.=20 > >>> > >>> I have removed the label property and will start a new thread in the= =20 > >>> topic. Any hints on which binding we could add this label prop ? =20 > >>> =20 > >> > >> Here I will provide just few thoughts about this new DT property. I do= n't > >> pretend this is what should be done. I still think other mtd maintaine= rs > >> should be involved to discuss this topic. > >> > >> First the DT property name "label" sounds good to me: it is consistent= with > >> "label" DT property used to name mtd partitions. However, I don't thin= k it > >> should be documented in jedec,spi-nor.txt but *maybe* in partition.txt= as > >> the purpose of this new DT property seems very close to the "label" > >> property of partition nodes: let's think about some hard-disk device > >> (/dev/sda) and its partition devices (/dev/sdaX). =20 >=20 > yes this is very similar. I first looked at introducing a name to=20 > an overall containing partition but the partition binding is not=20 > designed for that. There are constraints on the start address and > the size which does not fit the purpose. >=20 > > Hm, partition.txt may not be appropriate here. We're not documenting > > the MTD partition binding, but the MTD device one. Maybe we should > > create mtd.txt and put all generic MTD dev properties here. =20 > >> > >> Besides, the concept of this memory label is not limited to SPI NOR but > >> could also apply to NAND memories or any other MTD handled memories. = =20 > >=20 > > Definitely. Actually I think I'll need that for the Atmel NAND > > controller driver rework I'm currently working on, to keep mtdparts > > parser happy even after changing the NAND device naming scheme. > > =20 > >> Hence the DT property might be handled by drivers/mtd/ofpart.c instead= of > >> being handled by spi-nor.c or by each SPI NOR memory controller driver= . =20 > >=20 > > Actually, that could be done at the mtdcore level in > > mtd_set_dev_defaults() [1]. =20 >=20 > that would be perfect. >=20 > >> Finally, I guess we should take time to discuss and all agree what sho= uld > >> be done precisely before introducing a new DT property because one gen= eral > >> rule with DTB files is that users should be able to update their kernel > >> image (zImage, uImage, ...) without changing their DTB: device trees s= hould > >> be backward compatible. Hence if we make a wrong choice today, we are > >> likely to have to live with it and keep supporting that bad choice. =20 > >=20 > > Rob already acked the patch, so, if all MTD maintainers agree that this > > new property is acceptable, we should be fine ;-). =20 >=20 > yes but we would need to move the binding property to another file.=20 > What I sent applied to "jedec,spi-nor" and we want to generalize the=20 > property to other devices. We could create an new file under Documentation/devicetree/bindings/mtd/, or we could rename partition.txt into something else (generic.txt or common.txt) and document more than the partition binding. Can you take care of that (in a separate patch series of course)? Thanks, Boris