From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=us.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=miltonm@us.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=us.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44wmkp70c2zDqY2 for ; Sat, 4 May 2019 08:19:14 +1000 (AEST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x43MC7qq066488 for ; Fri, 3 May 2019 18:19:11 -0400 Received: from smtp.notes.na.collabserv.com (smtp.notes.na.collabserv.com [158.85.210.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s8w7aj869-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 03 May 2019 18:19:10 -0400 Received: from localhost by smtp.notes.na.collabserv.com with smtp.notes.na.collabserv.com ESMTP for from ; Fri, 3 May 2019 22:19:10 -0000 Received: from us1b3-smtp04.a3dr.sjc01.isc4sb.com (10.122.203.161) by smtp.notes.na.collabserv.com (10.122.47.50) with smtp.notes.na.collabserv.com ESMTP; Fri, 3 May 2019 22:19:06 -0000 Received: from us1b3-mail228.a3dr.sjc03.isc4sb.com ([10.168.214.55]) by us1b3-smtp04.a3dr.sjc01.isc4sb.com with ESMTP id 2019050322190581-883449 ; Fri, 3 May 2019 22:19:05 +0000 In-Reply-To: <0e8fa572-e01b-4c42-8544-a8a564256315@www.fastmail.com> Subject: Re: [PATCH dev-5.0 3/4] mtd: spi-nor: aspeed: use memcpy_fromio() to capture the optimization buffer From: "Milton Miller II" To: "Andrew Jeffery" Cc: "=?ISO-8859-1?Q?C=E9dric_Le_Goater?=" , openbmc@lists.ozlabs.org Date: Fri, 3 May 2019 22:19:06 +0000 MIME-Version: 1.0 Sensitivity: Importance: Normal X-Priority: 3 (Normal) References: <0e8fa572-e01b-4c42-8544-a8a564256315@www.fastmail.com>, <20190417133941.22962-4-clg@kaod.org> <20190417133941.22962-1-clg@kaod.org>

<090455f7-21dd-4e96-888e-1b23592bdfa3@www.fastmail.com> X-Mailer: IBM iNotes ($HaikuForm 1048) | IBM Domino Build SCN1812108_20180501T0841_FP38 April 10, 2019 at 11:56 X-LLNOutbound: False X-Disclaimed: 8247 X-TNEFEvaluated: 1 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 x-cbid: 19050322-7769-0000-0000-0000069CFB46 X-IBM-SpamModules-Scores: BY=0; FL=0; FP=0; FZ=0; HX=0; KW=0; PH=0; SC=0.388783; ST=0; TS=0; UL=0; ISC=; MB=0.255067 X-IBM-SpamModules-Versions: BY=3.00011043; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000285; SDB=6.01198164; UDB=6.00628489; IPR=6.00979026; BA=6.00006298; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00026720; XFM=3.00000015; UTC=2019-05-03 22:19:09 X-IBM-AV-DETECTION: SAVI=unsuspicious REMOTE=unsuspicious XFE=unused X-IBM-AV-VERSION: SAVI=2019-05-03 20:09:11 - 6.00009881 x-cbparentid: 19050322-7770-0000-0000-000030B41DA0 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-05-03_14:, , signatures=0 X-Proofpoint-Spam-Reason: safe X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 May 2019 22:19:15 -0000 On 05/01/2019 10:53PM in some timezone, Andrew Jeffery wr= ote: >On Fri, 19 Apr 2019, at 17:39, C=C3=A9dric Le Goater wrote:>> On 4/19/19 9= :23 AM, Andrew Jeffery wrote: >> > Hi C=C3=A9dric >> >=20 >> > On Fri, 19 Apr 2019, at 15:32, C=C3=A9dric Le Goater wrote: >> >> On 4/19/19 3:03 AM, Andrew Jeffery wrote: >> >>> >> >>> >> >>> On Fri, 19 Apr 2019, at 06:53, Milton Miller II wrote: >> >>>> About 04/17/2019 09:20AM in some timezone, C=C3=A9dric Le Goater >wrote: >> >>>> >> >>>> >> >>>>> aspeed=5Fsmc=5Fread=5Ffrom=5Fahb() only reads the first word which= is >not >> >>>>> what >> >>>>> we want. We want to capture a CALIBRATE=5FBUF=5FSIZE size window >of the >> >>>>> flash contents to optimize the read. >> >>>>> >> >>>> >> >>>> NACK >> >>>> >> >>>> This justifcation is false. The routine reads the whole >buffer >> >>>> because it calls the =5Frep routine and takes the size. >> >> >> >> It doesn't AFAICT looking at other drivers and also from my >test. >> >> >> >>>> In addition, the comment just before aspeed=5Fsmc=5Fread=5Ffrom=5Fa= hb >> >>>> tells why memcpy=5Ffromio and memcpy=5Ftoio are broken on 32 bit >> >> >> >> That might have been the case on Linux 4.7. It doesn't seem to >be=20 >> >> the case anymore. See below. >> >> >> >>>> arm, and this is still the case judging from the recent bug >> >>>> reportfrom a Nuvaton user [1]. >> >>>> >> >>>> [1] >https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A=5F=5Fgithub.com=5Fop= enb >mc=5Fopenbmc=5Fissues=5F3521&d=3DDwIFaQ&c=3Djf=5FiaSHvJObTbx-siA1ZOg&r=3Db= vv7AJEECo >RKBU02rcu4F5DWd-EwX8As2xrXeO9ZSo4&m=3DsK1b4XTLYG8JeD8M-9ido3CQX=5FAOERqbR >DK4EyTZHWc&s=3DfYtUMc0yvOgIU3iNg2S3anMU3YSmstjFPxQR3JpCtco&e=3D >> >>>> >> >>>> Andrew, Please revert this patch. >> >> >> >> I don't think you have enough convincing arguments for that. >> >=20 >> > That may be the case, but having seen the pain of the original >corruption >> > problems that drove the ioreadX=5Frep() implementation above, >Milton's >> > protest combined with my initial, briefly nagging concern was >enough for >> > me to revert. Two things here: >> >=20 >> > 1. We've run without this patch for quite some time. Despite >oddities, >> > the existing implementation has been stable >> > 2. With patch 4/4, you've resolved the 4B corruption problem. >This was >> > the immediate concern, as it was impacting teams developing and >> > testing OpenBMC master. I appreciate the effort you put into >hunting >> > that down, the root cause was certainly not obvious. >> >=20 >> > From *my* testing we appear to be stable both with and without >this >> > change, however my concern is that *my* testing is not complete >enough >> > to be confident that we're not going to hit the subtle corruption >problems >> > that drove the introduction of the existing code. >>=20 >> QEMU would have caught this regression if SFDP was modeled. It does >today >> if 4B opcodes are forced on the mx25l25635e. Given the time the >team spent >> on this, I would say 1 or 2PM overall, QEMU is a good investment.=20 >> ^ >> | >> Managers are you reading this ? ------------------+=20 >>=20 >> > For some additional context, I'm now on leave until the 30th, and >Joel to >> > the 29th. These patches have been through a process that has >proceeded >> > much more hastily than I would have liked, and that's lead to >where we >> > are now. >> >=20 >> > With that in mind, less change is better, and so I have decided >to back >> > this patch out. It's a risk-based decision, not a reflection of >the effort, >> > desires or technicalities involved. >>=20 >> Back to where we were before, it's fine as it works.=20 >>=20 >> The optimize reads are just reading the first 4 bytes : >>=20 >> [ 14.130480] aspeed-smc 1e630000.spi: mx25l25635e (32768 Kbytes) >> [ 14.136664] aspeed-smc 1e630000.spi: write control register: >00122302 >> [ 14.143326] aspeed-smc 1e630000.spi: read control register: >203c2341 >> [ 14.149750] aspeed-smc 1e630000.spi: AHB frequency: 192 MHz >> [ 14.181561] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.188894] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.196230] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.203558] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.210751] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.218067] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.225397] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.232722] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.239912] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >> [ 14.247232] 50 41 52 54 50 41 52 54 50 41 52 54 50 41 52 54 >PARTPARTPARTPART >>=20 >> with memcpy=5Ffromio : >>=20 >> [ 13.779087] aspeed-smc 1e630000.spi: mx25l25635e (32768 Kbytes) >> [ 13.785255] aspeed-smc 1e630000.spi: write control register: >00122302 >> [ 13.791762] aspeed-smc 1e630000.spi: read control register: >203c2341 >> [ 13.798326] aspeed-smc 1e630000.spi: AHB frequency: 192 MHz >> [ 13.815420] 50 41 52 54 00 00 00 01 00 00 00 01 00 00 00 80 >PART............ >> [ 13.822759] 00 00 00 1b 00 00 10 00 00 00 20 00 00 00 00 00 >.......... ..... >> [ 13.829946] 00 00 00 00 00 00 00 00 00 00 00 00 50 41 62 cf >............PAb. >> [ 13.837266] 70 61 72 74 00 00 00 00 00 00 00 00 00 00 00 00 >part............ >> [ 13.844597] 00 00 00 00 00 00 00 01 ff ff ff ff 00 00 00 01 >................ >> [ 13.851788] 00 00 00 03 00 00 00 01 00 00 10 00 00 00 00 00 >................ >> [ 13.859105] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >................ >> [ 13.866433] 00 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >.@.............. >> [ 13.873759] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >................ >> [ 13.880951] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >................ >> [ 13.888267] 00 00 00 00 00 00 00 00 00 00 00 00 8f de 9d 89 >................ >> [ 13.895591] 48 42 49 00 00 00 00 00 00 00 00 00 00 00 00 00 >HBI............. >> [ 13.902917] 00 00 00 10 00 00 05 a0 ff ff ff ff 00 00 00 02 >................ >>=20 >>=20 >> I should have added these tests in the commit log. Sorry about >that. >> We will see later on. There are no hurries for this fix. >Optimization >> is still being done. > >Milton: Given you NACK'ed the patch I'd appreciate a follow-up in >light of >this data. > Yes, I should have replied last week. I accept the difference between the case where it fails and=20 the case where its used is the difference between read mode,=20 where the chip verifies the address of each access, and user=20 mode, where the region is decoded at the block level and the=20 data is routed through a fifo, where extra reads or writes=20 are problematic. That said, it will work for read, or where the source and=20 destination have the same alignemnt. The memcpy routine will=20 cause two transactions in the spi controller, but the result=20 will function. I'm not sure a write would work. I withdraw my NACK. milton