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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB624C433F5 for ; Wed, 18 May 2022 10:08:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234970AbiERKH6 (ORCPT ); Wed, 18 May 2022 06:07:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234959AbiERKHy (ORCPT ); Wed, 18 May 2022 06:07:54 -0400 Received: from 6.mo548.mail-out.ovh.net (6.mo548.mail-out.ovh.net [188.165.58.48]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 072DD20F52 for ; Wed, 18 May 2022 03:07:51 -0700 (PDT) Received: from mxplan5.mail.ovh.net (unknown [10.108.1.6]) by mo548.mail-out.ovh.net (Postfix) with ESMTPS id A88812369D; Wed, 18 May 2022 08:52:00 +0000 (UTC) Received: from kaod.org (37.59.142.107) by DAG4EX1.mxp5.local (172.16.2.31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.6; Wed, 18 May 2022 10:51:59 +0200 Authentication-Results: garm.ovh; auth=pass (GARM-107S0014f754fc7-15cb-49af-bbdd-8a187c23a99f, DB10E105899AAE3BCA8ABEF0D93527152A7ECCF8) smtp.auth=clg@kaod.org X-OVh-ClientIp: 82.64.250.170 Message-ID: Date: Wed, 18 May 2022 10:51:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [RFC PATCH 3/6] mtd: spi-nor: core: run calibration when initialization is done Content-Language: en-US To: Pratyush Yadav , Miquel Raynal CC: Nishanth Menon , Tero Kristo , Rob Herring , Tudor Ambarus , Michael Walle , Richard Weinberger , Vignesh Raghavendra , Mark Brown , , , , , , Joel Stanley References: <20210311191216.7363-1-p.yadav@ti.com> <20210311191216.7363-4-p.yadav@ti.com> <20220517160226.4107f282@xps-13> <20220518060640.os5fp5rez4ie7qc4@ti.com> <20220518091931.279c5398@xps-13> <20220518075651.mvdhfnfbgutecgyq@ti.com> From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= In-Reply-To: <20220518075651.mvdhfnfbgutecgyq@ti.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [37.59.142.107] X-ClientProxiedBy: DAG1EX2.mxp5.local (172.16.2.2) To DAG4EX1.mxp5.local (172.16.2.31) X-Ovh-Tracer-GUID: 37372b08-b3f9-44cc-83f6-bcc565d4553b X-Ovh-Tracer-Id: 12947848930754923396 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvfedrheelgddtjecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefkffggfgfuvfevfhfhjggtgfhisehtjeertddtfeejnecuhfhrohhmpeevrogurhhitggpnfgvpgfiohgrthgvrhcuoegtlhhgsehkrghougdrohhrgheqnecuggftrfgrthhtvghrnhepleelieeigfekfeeitddvieegteeuteekffekleehuefgteetgedvkefghefggfeknecukfhppedtrddtrddtrddtpdefjedrheelrddugedvrddutdejnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmohguvgepshhmthhpohhuthdphhgvlhhopehmgihplhgrnhehrdhmrghilhdrohhvhhdrnhgvthdpihhnvghtpedtrddtrddtrddtpdhmrghilhhfrhhomheptghlgheskhgrohgurdhorhhgpdhnsggprhgtphhtthhopedupdhrtghpthhtohepjhhovghlsehjmhhsrdhiugdrrghu Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On 5/18/22 09:56, Pratyush Yadav wrote: > On 18/05/22 09:19AM, Miquel Raynal wrote: >> Hi Pratyush, >> >> p.yadav@ti.com wrote on Wed, 18 May 2022 11:37:05 +0530: >> >>> +Cedric >>> >>> On 17/05/22 04:02PM, Miquel Raynal wrote: >>>> Hi Pratyush, >>>> >>>> p.yadav@ti.com wrote on Fri, 12 Mar 2021 00:42:13 +0530: >>>> >>>>> Once the flash is initialized tell the controller it can run >>>>> calibration procedures if needed. This can be useful when calibration is >>>>> needed to run at higher clock speeds. >>>>> >>>>> Signed-off-by: Pratyush Yadav >>>>> --- >>>>> drivers/mtd/spi-nor/core.c | 12 ++++++++++-- >>>>> 1 file changed, 10 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c >>>>> index 88888df009f0..e0cbcaf1be89 100644 >>>>> --- a/drivers/mtd/spi-nor/core.c >>>>> +++ b/drivers/mtd/spi-nor/core.c >>>>> @@ -3650,6 +3650,7 @@ static int spi_nor_probe(struct spi_mem *spimem) >>>>> * checking what's really supported using spi_mem_supports_op(). >>>>> */ >>>>> const struct spi_nor_hwcaps hwcaps = { .mask = SNOR_HWCAPS_ALL }; >>>>> + struct spi_mem_op op; >>>>> char *flash_name; >>>>> int ret; >>>>> >>>>> @@ -3709,8 +3710,15 @@ static int spi_nor_probe(struct spi_mem *spimem) >>>>> if (ret) >>>>> return ret; >>>>> >>>>> - return mtd_device_register(&nor->mtd, data ? data->parts : NULL, >>>>> - data ? data->nr_parts : 0); >>>>> + ret = mtd_device_register(&nor->mtd, data ? data->parts : NULL, >>>>> + data ? data->nr_parts : 0); >>>>> + if (ret) >>>>> + return ret; >>>>> + >>>>> + op = spi_nor_spimem_get_read_op(nor); >>>> >>>> Isn't this too specific? I really don't know much about spi-nors, but I >>>> find odd to have this op being created here, why not moving this into >>>> the _do_calibration() helper? >>> >>> Maybe the naming confused you but this is a function in the SPI NOR >>> core, not in SPI MEM. SPI NOR supports both SPI MEM based controllers >>> and "legacy" controllers, so the convention is to add the "spimem" >>> prefix before SPI MEM specific functions. So I don't get the comment >>> about it being too specific. It is too specific to what? >> >> Mmh right, it's fine then. >> >>> >>> And how can spi_mem_do_calibration() know what op the flash uses to read >>> data? SPI NOR or SPI NAND would know it, but not SPI MEM. That is why we >>> pass in that information to spi_mem_do_calibration(). >> >> But here the op is "spi-nor wide", I would have expected a >> per-device op. But that is not a big deal, that is something that can >> also be updated later if needed I guess. > > It is per-device. The op is generated using nor->read_opcode, > nor->addr_width, nor->read_dummy, etc. So if you have 2 NOR flashes on > your system with different opcodes, it would work for both. > >> >> One last question, is there something that mtd_device_register() does >> that is really needed for the calibration to work? Otherwise I would >> rather prefer to have that calibration happening before the user gets >> access to the device. Which would mean calling it right after : ret = spi_nor_create_read_dirmap(nor); if (ret) return ret; ret = spi_nor_create_write_dirmap(nor); if (ret) return ret; > The calibration works by reading a known pattern that is already written > to the flash again and again and seeing what delays work and what don't. > For that to happen, the controller driver needs to know where the > pattern is stored. Why don't you simply choose some random place, first 16KB for instance, and check that the data is random enough ? If not, declare calibration not possible and choose a default safe setting which is anyhow a requirement for calibration. Retry at reboot as data might have changed. > This series does that by looking at the MTD > partitions. For that to happen, we need to create those partitions > first, which happens after mtd_device_register(). hmm, that might work for some boards. This is not at all the case for the BMC boards. Vendors can put any kind of flash model and/or layout and the driver needs to be more generic. > But I am planning to use device tree to get that information now so this > should no longer be needed and we can do calibration before registering > the device with MTD. Perfect, we can move the calibration hook in spi_nor_create_read_dirmap() then, or in devm_spi_mem_dirmap_create(), which would make more sense IMHO. Thanks, C.