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=-7.0 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 CE801C282D7 for ; Fri, 8 Feb 2019 14:24:39 +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 9F28D20863 for ; Fri, 8 Feb 2019 14:24:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="itQob527"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Nz/j3uMD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F28D20863 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject: In-Reply-To:References:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=HxT3vbBROapXb/pkSavW+ImjQXj66zWxAYJBWZNtn6o=; b=itQob52768Z9JI WYvh/lchsPPM0kJ5rHEAsQuht62XP5omPgmkWq2GF/6sEDXilsrm9YKsYWGHUdU0Q0FoUeTQmt3ij ZMGTyTg65y63IeZkKIivC5CKAbBF3ltO+kWnbww3aAKj9SU5Tfe9FTR21w5grhxz16BOyvNorv2l1 RjdOGb5d/oproZYVSCx8k1koqzaVsPgR9/xKJXcR+l7ZLYm/a8vaaXmlRJSI/w7GcApy2tt37sdBj qp/ijl/yQvnD0ZdV/acnyaa9Adlmgqye0VUeEDvtTW82XHuqL9PXICPIzp6ePoHgjOufxzsqjCorM ys2GFKFIJIaPFcxmfzJA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gs753-0005T5-0V; Fri, 08 Feb 2019 14:24:37 +0000 Received: from mail-pf1-x444.google.com ([2607:f8b0:4864:20::444]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gs74w-0005S8-Sv for linux-mtd@lists.infradead.org; Fri, 08 Feb 2019 14:24:34 +0000 Received: by mail-pf1-x444.google.com with SMTP id j3so1721415pfi.12 for ; Fri, 08 Feb 2019 06:24:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:references:in-reply-to:subject:date:message-id :mime-version:content-transfer-encoding:thread-index :content-language; bh=x+4xnTqcwhgr98uo5XuFLhUJxPlaJMi636SG2kQk7Gc=; b=Nz/j3uMDOKKjlKfg8XkmSjsG+hq2GR57pmu0ELyhtTHaop/CIhVuBiNmxAs7/l4tAN IH7DDFeg2O3lQoH2msMZB5B/Sv3dSO44F6NfISmiVVc7i9K5li5IFXUSL7dPPHAUnBjv jHyoBdO8IFrRB80q/A2jg0qitDMXVHmjY4Ez3kpFaSd3gxAJ/Nvk1nYi1eGg++1lnmJt MrI3kFS/n2Txb5QmiVQ2LNf0Vr6jmxZOshrL9lUmPxHBd4g0MYkMnfBQNjK+QzeZHrNz JIu0KcWGIax+ElLWafh0ggLLr1yya+MvO4fdqhuyfebBHtxJa4pd3ifXt4wMsLODY4Cf +ArQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:references:in-reply-to:subject:date :message-id:mime-version:content-transfer-encoding:thread-index :content-language; bh=x+4xnTqcwhgr98uo5XuFLhUJxPlaJMi636SG2kQk7Gc=; b=TN/sfwLeZ2tkFYTampBMnhfbykTQtczuOq+ttlrjH+cL0yZr/hBXU5xf805HVf7TuX bEFjj3xOkEfDujpSh8lI8vrYHrW7Cy/0fF6kvPy3CVpXYgfxVJr7/ZQ4dTT6PqFA461+ O5BfHnHu7nQm1eV1m61XScWVnaRfVQtl2qy100y3hKrTw08fcuK1pHAUQhD9/YVM/w+4 35a/AYIgC9/IvjBkr/cSAKsOJW68hTrhGRXxLtT7W6Y7s7tlAO5P74ht3X686bZU50Qc HaCOA7ZNacaA0nGapx/7rYV+2TtubIbbeg0KbQwPH4L4VpUw7DQ97GU1KVUOFWDETccp uEAQ== X-Gm-Message-State: AHQUAuYDUCj17xARuXP1CH2QGt94korsi64Tn+kGLwXsQX2jsVk2cttY 5YO4+zkI2M77rsuU+L1jTlY= X-Google-Smtp-Source: AHgI3IY4R6s1tLE+JvJyuE1UiIUeBdRtoYeDhXLsW1itG54bMV7XXx3OOKwfh+GIO/qb+YohauwqiA== X-Received: by 2002:a62:1c86:: with SMTP id c128mr23246203pfc.54.1549635869414; Fri, 08 Feb 2019 06:24:29 -0800 (PST) Received: from ikegamiPC (M106072039032.v4.enabler.ne.jp. [106.72.39.32]) by smtp.gmail.com with ESMTPSA id f12sm2680980pgo.13.2019.02.08.06.24.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 Feb 2019 06:24:28 -0800 (PST) From: "Tokunori Ikegami" To: "'Sobon, Przemyslaw'" , "'Boris Brezillon'" References: <1548977439-318904-1-git-send-email-liujian56@huawei.com> <20190203092645.18d1495b@bbrezillon> <20190203093509.269bf1e1@bbrezillon> <20190207095635.0fc3b411@kernel.org> <193621849.44066.1549580387922.JavaMail.yahoo@mail.yahoo.co.jp> <632ed76bd3844ceab75066d1f30a7115@EX13D07UWA001.ant.amazon.com> In-Reply-To: <632ed76bd3844ceab75066d1f30a7115@EX13D07UWA001.ant.amazon.com> Subject: RE: Re: [PATCH] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer Date: Fri, 8 Feb 2019 23:23:59 +0900 Message-ID: <149101d4bfb9$fdc5a330$f950e990$@gmail.com> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQKzD+8bzTNJb3fYn6g+Txlclt4a6gHKPVnTAnthz5oB7umc8AJnC6FFAd0fx9ABvvwx96O3jtDw Content-Language: ja X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190208_062431_079708_77EF88E6 X-CRM114-Status: GOOD ( 36.34 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: keescook@chromium.org, joakim.tjernlund@infinera.com, richard@nod.at, linux-kernel@vger.kernel.org, marek.vasut@gmail.com, ikegami_to@yahoo.co.jp, linux-mtd@lists.infradead.org, computersforpeace@gmail.com, dwmw2@infradead.org, 'Liu Jian' Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org Hi Przemek-san, Thank you so much for your explanation. > I have seen a case myself where a value was written, chip changed > state to "ready" but when I was reading the value was incorrect. I also know the similar issues for the both buffer and word write. Both issues were able to reproduce the write error behavior. Note: The word write issue is able to reproduce now also. Those were resolved by using chip_good() instead to check the state. > This can happen as result of intermittent issue with flash. It is > hard to fall into scenario when testing on limited number of devices > but with large enough population you can see that. If possible I would like to know the issue detail and its cause also. > Another situation > is when a flash chip reaches its maximum number of writes. So for > example a chip is designed for 100k writes to a page. Once you > reach that number of writes you can have invalid data written to > flash but chip itself reports everything was good and switches to > "ready" state. Yes I see. Regards, Ikegami > -----Original Message----- > From: linux-mtd [mailto:linux-mtd-bounces@lists.infradead.org] On Behalf > Of Sobon, Przemyslaw > Sent: Friday, February 8, 2019 8:51 AM > To: ikegami_to@yahoo.co.jp; Boris Brezillon > Cc: keescook@chromium.org; marek.vasut@gmail.com; > ikegami@allied-telesis.co.jp; richard@nod.at; > linux-kernel@vger.kernel.org; joakim.tjernlund@infinera.com; > linux-mtd@lists.infradead.org; computersforpeace@gmail.com; > dwmw2@infradead.org; Liu Jian > Subject: RE: Re: [PATCH] cfi: fix deadloop in cfi_cmdset_0002.c > do_write_buffer > > Hi Ikegami, > > I have seen a case myself where a value was written, chip changed > state to "ready" but when I was reading the value was incorrect. > This can happen as result of intermittent issue with flash. It is > hard to fall into scenario when testing on limited number of devices > but with large enough population you can see that. Another situation > is when a flash chip reaches its maximum number of writes. So for > example a chip is designed for 100k writes to a page. Once you > reach that number of writes you can have invalid data written to > flash but chip itself reports everything was good and switches to > "ready" state. > > Hope this explanation is clear. Please let me know. > > Regards, > Przemek > > > -----Original Message----- > > From: ikegami_to@yahoo.co.jp > > Sent: Thursday, February 7, 2019 3:00 PM > > > > Hi Przemek-san, > > > > Could you please explain the case detail that the value is written > incorrectly? > > I think that the value is only written correctly except a bug. > > > > Regards, > > Ikegami > > > > --- boris.brezillon@collabora.com wrote --- : > > > Hi Sobon, > > > > > > On Tue, 5 Feb 2019 22:28:44 +0000 > > > "Sobon, Przemyslaw" wrote: > > > > > > > > From: Boris Brezillon > > > > > Sent: Sunday, February 3, 2019 12:35 AM > > > > > > +Przemyslaw > > > > > > > > > > > > On Fri, 1 Feb 2019 07:30:39 +0800 Liu Jian > > > > > > wrote: > > > > > > > > > > > > > In function do_write_buffer(), in the for loop, there is a > > > > > > > case > > > > > > > chip_ready() returns 1 while chip_good() returns 0, so it > > > > > > > never break the loop. > > > > > > > To fix this, chip_good() is enough and it should timeout if > it > > > > > > > stay bad for a while. > > > > > > > > > > > > Looks like Przemyslaw reported and fixed the same problem. > > > > > > > > > > > > > > > > > > > > Fixes: dfeae1073583(mtd: cfi_cmdset_0002: Change write buffer > > > > > > > to check correct value) > > > > > > > > > > > > Can you put the Fixes tag on a single, and the format is > > > > > > > > > > > > Fixes: ("message") > > > > > > > > > > > > > Signed-off-by: Yi Huaijie > > > > > > > Signed-off-by: Liu Jian > > > > > > > > > > > > [1]http://patchwork.ozlabs.org/patch/1025566/ > > > > > > > > > > > > > --- > > > > > > > drivers/mtd/chips/cfi_cmdset_0002.c | 6 +++--- > > > > > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > > > > > > > > > diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c > > > > > > > b/drivers/mtd/chips/cfi_cmdset_0002.c > > > > > > > index 72428b6..818e94b 100644 > > > > > > > --- a/drivers/mtd/chips/cfi_cmdset_0002.c > > > > > > > +++ b/drivers/mtd/chips/cfi_cmdset_0002.c > > > > > > > @@ -1876,14 +1876,14 @@ static int __xipram > do_write_buffer(struct map_info *map, struct flchip *chip, > > > > > > > continue; > > > > > > > } > > > > > > > > > > > > > > - if (time_after(jiffies, timeo) && !chip_ready(map, > adr)) > > > > > > > - break; > > > > > > > - > > > > > > > if (chip_good(map, adr, datum)) { > > > > > > > xip_enable(map, chip, adr); > > > > > > > goto op_done; > > > > > > > } > > > > > > > > > > > > > > + if (time_after(jiffies, timeo)) > > > > > > > + break; > > > > > > > + > > > > > > > /* Latency issues. Drop the lock, wait a while and > retry */ > > > > > > > UDELAY(map, chip, adr, 1); > > > > > > > } > > > > > > > > > > > > > > > > BTW, the patch itself looks good to me. Ikegami, can you confirm > it does the right thing? > > > > > > > > > > Thanks, > > > > > > > > > > Boris > > > > > > > > > > > > > One comment to this patch. If value is written incorrectly quickly > > > > we will be stuck in the loop even though nothing is going to change. > > > > For example a value was written incorrectly after 1us, the loop was > > > > set to 1ms, function will return after 1ms, this solution is not > > > > optimized for performance. I considered same when working on this > change and decided to do it different way. > > > > > > Seems like you're right if we assume that checking for GOOD state does > > > not require a delay after the READY check, but if that's not the case > > > and an extra delay is actually required, you might end up with a BAD > > > status while it could have turned GOOD at some point with the 'check > > > only for GOOD state until we timeout' approach. > > > > > > TBH, I don't know how CFI flashes work, so I'll let you guys sort this > > > out. > > > > > > Regards, > > > > > > Boris > > > > > > ______________________________________________________ > > > Linux MTD discussion mailing list > > > http://lists.infradead.org/mailman/listinfo/linux-mtd/ > > > > > > > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/ ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/