From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84ADAC8300A for ; Thu, 30 Apr 2020 12:52:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61D2B2074A for ; Thu, 30 Apr 2020 12:52:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726850AbgD3MwM (ORCPT ); Thu, 30 Apr 2020 08:52:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726127AbgD3MwM (ORCPT ); Thu, 30 Apr 2020 08:52:12 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B821BC035494 for ; Thu, 30 Apr 2020 05:52:11 -0700 (PDT) Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 631232A274B; Thu, 30 Apr 2020 13:52:08 +0100 (BST) Date: Thu, 30 Apr 2020 14:52:05 +0200 From: Boris Brezillon To: Ricardo Ribalda Delgado Cc: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , linux-mtd@lists.infradead.org, LKML , Tudor Ambarus Subject: Re: [PATCH v2] mtd: Fix mtd not the same name not registered if nvmem Message-ID: <20200430145205.06e16bd4@collabora.com> In-Reply-To: References: <20200401100240.445447-1-ribalda@kernel.org> <20200402065953.9974-1-ribalda@kernel.org> <20200427162222.1c2b2c85@xps13> <20200427163711.07614619@collabora.com> <20200427164922.5829717f@xps13> <20200427211024.174f5830@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 30 Apr 2020 14:26:51 +0200 Ricardo Ribalda Delgado wrote: > Hi > > On Mon, Apr 27, 2020 at 9:10 PM Boris Brezillon > wrote: > > > > On Mon, 27 Apr 2020 16:49:22 +0200 > > Miquel Raynal wrote: > > > > > Hi Boris, > > > > > > Boris Brezillon wrote on Mon, 27 Apr > > > 2020 16:37:11 +0200: > > > > > > > On Mon, 27 Apr 2020 16:22:22 +0200 > > > > Miquel Raynal wrote: > > > > > > > > > Hi Ricardo, > > > > > > > > > > Ricardo Ribalda Delgado wrote on Tue, 14 Apr 2020 > > > > > 15:47:23 +0200: > > > > > > > > > > > Ping? > > > > > > > > > > > > On Thu, Apr 2, 2020 at 8:59 AM Ricardo Ribalda Delgado > > > > > > wrote: > > > > > > > > > > > > > > When the nvmem framework is enabled, a nvmem device is created per mtd > > > > > > > device/partition. > > > > > > > > > > > > > > It is not uncommon that a device can have multiple mtd devices with > > > > > > > partitions that have the same name. Eg, when there DT overlay is allowed > > > > > > > and the same device with mtd is attached twice. > > > > > > > > > > > > > > Under that circumstances, the mtd fails to register due to a name > > > > > > > duplication on the nvmem framework. > > > > > > > > > > > > > > With this patch we add a _1, _2, _X to the subsequent names if there is > > > > > > > a collition, and throw a warning, instead of not starting the mtd > > > > > > > device. > > > > > > > > > > > > > > [ 8.948991] sysfs: cannot create duplicate filename '/bus/nvmem/devices/Production Data' > > > > > > > [ 8.948992] CPU: 7 PID: 246 Comm: systemd-udevd Not tainted 5.5.0-qtec-standard #13 > > > > > > > [ 8.948993] Hardware name: AMD Dibbler/Dibbler, BIOS 05.22.04.0019 10/26/2019 > > > > > > > [ 8.948994] Call Trace: > > > > > > > [ 8.948996] dump_stack+0x50/0x70 > > > > > > > [ 8.948998] sysfs_warn_dup.cold+0x17/0x2d > > > > > > > [ 8.949000] sysfs_do_create_link_sd.isra.0+0xc2/0xd0 > > > > > > > [ 8.949002] bus_add_device+0x74/0x140 > > > > > > > [ 8.949004] device_add+0x34b/0x850 > > > > > > > [ 8.949006] nvmem_register.part.0+0x1bf/0x640 > > > > > > > ... > > > > > > > [ 8.948926] mtd mtd8: Failed to register NVMEM device > > > > > > > > > > > > > > Signed-off-by: Ricardo Ribalda Delgado > > > > > > > > > > Thanks for proposing this change. Indeed we are aware of the problem > > > > > and the best solution that we could come up with was to create an > > > > > additional "unique_name" field to the mtd_info structure. This new > > > > > field would have the form: > > > > > > > > > > [] > > > > > > > > > > The separator might be '~' (but I am completely open on that), and that > > > > > would give for instance: > > > > > > > > > > my-controller~my-device~my-part~mysub-part > > > > > > > > I'd prefer something slightly more standard for the separator, like '/', > > > > which is what we usually use when we want to represent a path in a tree. > > > > I do agree on the general approach though. > > > > > > I am not sure / is a valid separator here we would use this > > > name to create a sysfs entry. Would it work? > > > > Hm, you're probably right, I didn't check how the name was used by > > nvmem. I also see that partition names can contain spaces, which is > > not that great. So, if we want to use mtd->unique_name we should > > probably sanitize it before passing it to nvmem. All this makes me > > reconsider your initial proposal: use 'mtdX' as the nvmem name. It's > > unique and it's simple enough to not require this extra sanitization > > pass, on the other hand, guessing the nvmem partition based on such an > > opaque name is not simple, not to mention that the mtd device name can > > change depending on the probe order. > > > > I also wonder if creating nvmem devs unconditionally for all mtd > > devices is a good idea. Sounds like we should only do that if there's an > > explicit request to have one partition exposed as an nvmem. > > > > Note that, no matter what we decide about nvmem, I think having unique > > names at the MTD level is a good thing. > > I have no preference one way or another. > > The issue is that our current master leads to mtds not working fine > and making the system unusable. Whatever we decide it must be fast and > the patch backported. > > My original patch follows the same logic as led does where there is a > duplicated name. I can send a separate patch that uses mtdX and then > you decide what to pick. Or we can go with a third way, but it needs > to be soon ;). Please send a patch using dev_name(&mtd->dev), and let's hope it doesn't break someone else use case.