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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63C60C433EF for ; Wed, 29 Sep 2021 19:42:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3ED3561439 for ; Wed, 29 Sep 2021 19:42:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344189AbhI2ToL (ORCPT ); Wed, 29 Sep 2021 15:44:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244887AbhI2ToK (ORCPT ); Wed, 29 Sep 2021 15:44:10 -0400 Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C47EC06161C for ; Wed, 29 Sep 2021 12:42:29 -0700 (PDT) Received: by mail-lf1-x12a.google.com with SMTP id i19so12366469lfu.0 for ; Wed, 29 Sep 2021 12:42:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kempniu.pl; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=fpTJo9PN19CwOpgH8yiUSJNn3It4EQ9dC+3Al0lph7I=; b=tl/tsT2Nrh6yQ+Rl3+dJK0ANroWNYbYFblftSnt7NYLQkg3QBbxlmOGrafH2Y9dq60 T+9j4Aq0uVfWPZDjwLMqzhISmuzeLywWKwO3tUC6l+6mg1ycYLmEMc/sOK4jSrPbr/cT hYvlBN+kCNdan69XerxoD18kxuVU9ZCwThMkk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=fpTJo9PN19CwOpgH8yiUSJNn3It4EQ9dC+3Al0lph7I=; b=zDeLzCPrZcniPH+fFVlVlU7Q9FmyET8wBMuXwHx+Qz1Lw5NJLdRxG62iZofat9ES4f sY1guDSA+bzeulPpV6HWJNB6h2Yy01c2dLQCM0SynFzClW5MyXrzPEeAgsHfBMglOocH MPPzYQnc3ddCtJuIZqM7qUI+uVVumsy/h5+5bNw62rP5jH0wCae17l8sJ7wGOfGyRcmd ChhezpFZpWxAXJR+MpMgIruRsga/gRGmiLANcKowZfItwDsG+bhhthpdf6YTAHikfi4L 19oqcHhUuSLUAwbX/oVuMkCRwZiEcuTTYO60LDTGx49s91DBIjPuuWJCT+XNPOCg7Yv4 sVqw== X-Gm-Message-State: AOAM530VYVHyIH7oLCpPOs/QarpuJhr2DSYtrj2USb/hZvDK92WBZaoW 46N0t1/1lTPmOwMsiDfC1YttHw== X-Google-Smtp-Source: ABdhPJwU4jfdBet2tozUxiHUN7/qai9e5NS39a/T8NwbrMvUA4f4qE1xXnzZqQLEzNTuswAvuUVpCg== X-Received: by 2002:a05:6512:15a3:: with SMTP id bp35mr1436941lfb.11.1632944547503; Wed, 29 Sep 2021 12:42:27 -0700 (PDT) Received: from larwa.hq.kempniu.pl ([2001:470:64df:111::e02]) by smtp.gmail.com with ESMTPSA id 23sm86008ljq.83.2021.09.29.12.42.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Sep 2021 12:42:26 -0700 (PDT) Date: Wed, 29 Sep 2021 21:42:24 +0200 From: =?utf-8?B?TWljaGHFgiBLxJlwaWXFhA==?= To: Miquel Raynal Cc: Boris Brezillon , Richard Weinberger , Vignesh Raghavendra , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Boris Brezillon Subject: Re: [PATCH] mtd: add MEMREAD ioctl Message-ID: References: <20210920070221.10173-1-kernel@kempniu.pl> <20210928155859.433844cb@xps13> <20210928162402.6bb64fcf@collabora.com> <20210928163519.08cd1138@xps13> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210928163519.08cd1138@xps13> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Miquel, Boris, Thank you both for your input. > > I do agree that a new interface is needed, but if we're adding a new > > entry point, let's make sure it covers all possible use cases we have > > now. At the very least, I think we're missing info about the maximum > > number of corrected bits per ECC region on the portion being read. > > Propagating EUCLEAN errors is nice, but it's not precise enough IMHO. > > > > I remember discussing search a new READ ioctl with Sascha Hauer a few > > years back, but I can't find the discussion... I think this is the thread in question: https://www.infradead.org/pipermail/linux-mtd/2016-April/thread.html#67085 In fact, it looks like Boris beat me to preparing a draft patch adding a MEMREAD ioctl by some five years: https://www.infradead.org/pipermail/linux-mtd/2016-April/067187.html It is apparently true that "everything that can be invented has been invented"... :-) I did search the web for existing mentions of a MEMREAD ioctl before submitting my patch, but this thread did not turn up in the results :( Anyway, back in 2016, Sascha hinted that he might move forward with the draft prepared by Boris: https://www.infradead.org/pipermail/linux-mtd/2016-April/067215.html but I cannot find any related submissions from Sascha in linux-mtd's Patchwork. > We also discussed a mtd_io_op some time ago, which would equivalently > replace mtd_oob_ops at some point, including more information such as > the bitflips which happened on every chunk instead of the information > regarding the maximum number of bitflips in one of the chunks only. Is that discussion available online? Search engines seem to be oblivious to that term, which makes it hard for me to get acquainted with that idea and/or to comment on it ;) > IIRC the point was to get rid of the mtd_{read,write}{,_oob} hooks and > structures in favor of a more robust and complete set of operations. That sounds like a major overhaul, right? I guess the big question from my perspective is: should I revive Boris' original effort on the MEMREAD ioctl (which returns more detailed bitflip stats in the structure passed by user space) or would that be a waste of time because the subsystem will be switched over wholesale to a new way of doing I/O (mtd_io_op) in the foreseeable future and therefore exposing yet another ioctl to user space today would be frowned upon? -- Best regards, Michał Kępień 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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7967C433EF for ; Wed, 29 Sep 2021 19:43:46 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9ACCA61439 for ; 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Wed, 29 Sep 2021 12:42:26 -0700 (PDT) Date: Wed, 29 Sep 2021 21:42:24 +0200 From: =?utf-8?B?TWljaGHFgiBLxJlwaWXFhA==?= To: Miquel Raynal Cc: Boris Brezillon , Richard Weinberger , Vignesh Raghavendra , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Boris Brezillon Subject: Re: [PATCH] mtd: add MEMREAD ioctl Message-ID: References: <20210920070221.10173-1-kernel@kempniu.pl> <20210928155859.433844cb@xps13> <20210928162402.6bb64fcf@collabora.com> <20210928163519.08cd1138@xps13> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210928163519.08cd1138@xps13> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210929_124230_314969_B13265EC X-CRM114-Status: GOOD ( 22.70 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org TWlxdWVsLCBCb3JpcywKClRoYW5rIHlvdSBib3RoIGZvciB5b3VyIGlucHV0LgoKPiA+IEkgZG8g YWdyZWUgdGhhdCBhIG5ldyBpbnRlcmZhY2UgaXMgbmVlZGVkLCBidXQgaWYgd2UncmUgYWRkaW5n IGEgbmV3Cj4gPiBlbnRyeSBwb2ludCwgbGV0J3MgbWFrZSBzdXJlIGl0IGNvdmVycyBhbGwgcG9z c2libGUgdXNlIGNhc2VzIHdlIGhhdmUKPiA+IG5vdy4gQXQgdGhlIHZlcnkgbGVhc3QsIEkgdGhp bmsgd2UncmUgbWlzc2luZyBpbmZvIGFib3V0IHRoZSBtYXhpbXVtCj4gPiBudW1iZXIgb2YgY29y cmVjdGVkIGJpdHMgcGVyIEVDQyByZWdpb24gb24gdGhlIHBvcnRpb24gYmVpbmcgcmVhZC4KPiA+ IFByb3BhZ2F0aW5nIEVVQ0xFQU4gZXJyb3JzIGlzIG5pY2UsIGJ1dCBpdCdzIG5vdCBwcmVjaXNl IGVub3VnaCBJTUhPLgo+ID4gCj4gPiBJIHJlbWVtYmVyIGRpc2N1c3Npbmcgc2VhcmNoIGEgbmV3 IFJFQUQgaW9jdGwgd2l0aCBTYXNjaGEgSGF1ZXIgYSBmZXcKPiA+IHllYXJzIGJhY2ssIGJ1dCBJ IGNhbid0IGZpbmQgdGhlIGRpc2N1c3Npb24uLi4KCkkgdGhpbmsgdGhpcyBpcyB0aGUgdGhyZWFk IGluIHF1ZXN0aW9uOgoKICAgIGh0dHBzOi8vd3d3LmluZnJhZGVhZC5vcmcvcGlwZXJtYWlsL2xp bnV4LW10ZC8yMDE2LUFwcmlsL3RocmVhZC5odG1sIzY3MDg1CgpJbiBmYWN0LCBpdCBsb29rcyBs aWtlIEJvcmlzIGJlYXQgbWUgdG8gcHJlcGFyaW5nIGEgZHJhZnQgcGF0Y2ggYWRkaW5nIGEKTUVN UkVBRCBpb2N0bCBieSBzb21lIGZpdmUgeWVhcnM6CgogICAgaHR0cHM6Ly93d3cuaW5mcmFkZWFk Lm9yZy9waXBlcm1haWwvbGludXgtbXRkLzIwMTYtQXByaWwvMDY3MTg3Lmh0bWwKCkl0IGlzIGFw cGFyZW50bHkgdHJ1ZSB0aGF0ICJldmVyeXRoaW5nIHRoYXQgY2FuIGJlIGludmVudGVkIGhhcyBi ZWVuCmludmVudGVkIi4uLiA6LSkgIEkgZGlkIHNlYXJjaCB0aGUgd2ViIGZvciBleGlzdGluZyBt ZW50aW9ucyBvZiBhCk1FTVJFQUQgaW9jdGwgYmVmb3JlIHN1Ym1pdHRpbmcgbXkgcGF0Y2gsIGJ1 dCB0aGlzIHRocmVhZCBkaWQgbm90IHR1cm4KdXAgaW4gdGhlIHJlc3VsdHMgOigKCkFueXdheSwg YmFjayBpbiAyMDE2LCBTYXNjaGEgaGludGVkIHRoYXQgaGUgbWlnaHQgbW92ZSBmb3J3YXJkIHdp dGggdGhlCmRyYWZ0IHByZXBhcmVkIGJ5IEJvcmlzOgoKICAgIGh0dHBzOi8vd3d3LmluZnJhZGVh ZC5vcmcvcGlwZXJtYWlsL2xpbnV4LW10ZC8yMDE2LUFwcmlsLzA2NzIxNS5odG1sCgpidXQgSSBj YW5ub3QgZmluZCBhbnkgcmVsYXRlZCBzdWJtaXNzaW9ucyBmcm9tIFNhc2NoYSBpbiBsaW51eC1t dGQncwpQYXRjaHdvcmsuCgo+IFdlIGFsc28gZGlzY3Vzc2VkIGEgbXRkX2lvX29wIHNvbWUgdGlt ZSBhZ28sIHdoaWNoIHdvdWxkIGVxdWl2YWxlbnRseQo+IHJlcGxhY2UgbXRkX29vYl9vcHMgYXQg c29tZSBwb2ludCwgaW5jbHVkaW5nIG1vcmUgaW5mb3JtYXRpb24gc3VjaCBhcwo+IHRoZSBiaXRm bGlwcyB3aGljaCBoYXBwZW5lZCBvbiBldmVyeSBjaHVuayBpbnN0ZWFkIG9mIHRoZSBpbmZvcm1h dGlvbgo+IHJlZ2FyZGluZyB0aGUgbWF4aW11bSBudW1iZXIgb2YgYml0ZmxpcHMgaW4gb25lIG9m IHRoZSBjaHVua3Mgb25seS4KCklzIHRoYXQgZGlzY3Vzc2lvbiBhdmFpbGFibGUgb25saW5lPyAg U2VhcmNoIGVuZ2luZXMgc2VlbSB0byBiZQpvYmxpdmlvdXMgdG8gdGhhdCB0ZXJtLCB3aGljaCBt YWtlcyBpdCBoYXJkIGZvciBtZSB0byBnZXQgYWNxdWFpbnRlZAp3aXRoIHRoYXQgaWRlYSBhbmQv b3IgdG8gY29tbWVudCBvbiBpdCA7KQoKPiBJSVJDIHRoZSBwb2ludCB3YXMgdG8gZ2V0IHJpZCBv ZiB0aGUgbXRkX3tyZWFkLHdyaXRlfXssX29vYn0gaG9va3MgYW5kCj4gc3RydWN0dXJlcyBpbiBm YXZvciBvZiBhIG1vcmUgcm9idXN0IGFuZCBjb21wbGV0ZSBzZXQgb2Ygb3BlcmF0aW9ucy4KClRo YXQgc291bmRzIGxpa2UgYSBtYWpvciBvdmVyaGF1bCwgcmlnaHQ/CgpJIGd1ZXNzIHRoZSBiaWcg cXVlc3Rpb24gZnJvbSBteSBwZXJzcGVjdGl2ZSBpczogc2hvdWxkIEkgcmV2aXZlIEJvcmlzJwpv cmlnaW5hbCBlZmZvcnQgb24gdGhlIE1FTVJFQUQgaW9jdGwgKHdoaWNoIHJldHVybnMgbW9yZSBk ZXRhaWxlZApiaXRmbGlwIHN0YXRzIGluIHRoZSBzdHJ1Y3R1cmUgcGFzc2VkIGJ5IHVzZXIgc3Bh Y2UpIG9yIHdvdWxkIHRoYXQgYmUgYQp3YXN0ZSBvZiB0aW1lIGJlY2F1c2UgdGhlIHN1YnN5c3Rl bSB3aWxsIGJlIHN3aXRjaGVkIG92ZXIgd2hvbGVzYWxlIHRvIGEKbmV3IHdheSBvZiBkb2luZyBJ L08gKG10ZF9pb19vcCkgaW4gdGhlIGZvcmVzZWVhYmxlIGZ1dHVyZSBhbmQgdGhlcmVmb3JlCmV4 cG9zaW5nIHlldCBhbm90aGVyIGlvY3RsIHRvIHVzZXIgc3BhY2UgdG9kYXkgd291bGQgYmUgZnJv d25lZCB1cG9uPwoKLS0gCkJlc3QgcmVnYXJkcywKTWljaGHFgiBLxJlwaWXFhAoKX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCkxpbnV4IE1URCBk aXNjdXNzaW9uIG1haWxpbmcgbGlzdApodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFu L2xpc3RpbmZvL2xpbnV4LW10ZC8K