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Sat, 18 Jul 2020 05:35:06 +0000 From: To: Subject: Re: [PATCH 2/2] mtd: spi-nor: Support SPI_NOR_DUAL_READ on Micron mt25qu02g. Thread-Topic: [PATCH 2/2] mtd: spi-nor: Support SPI_NOR_DUAL_READ on Micron mt25qu02g. Thread-Index: AQHWXCW58IWRpdQGEEW5x0rkX33S3A== Date: Sat, 18 Jul 2020 05:35:06 +0000 Message-ID: <6c29b0f3-65d3-1e69-58ce-cbb84c88910a@microchip.com> References: <20200716211631.38949-1-dac2@pensando.io> <20200716211631.38949-3-dac2@pensando.io> <1724beec-aceb-b6e9-1288-da340d3fd43c@microchip.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 authentication-results: pensando.io; dkim=none (message not signed) header.d=none;pensando.io; dmarc=none action=none header.from=microchip.com; x-originating-ip: [86.122.210.166] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 1d1ebaae-c21d-4b50-3399-08d82adc5431 x-ms-traffictypediagnostic: BYAPR11MB3575: x-microsoft-antispam-prvs: x-bypassexternaltag: True x-ms-oob-tlc-oobclassifiers: OLM:9508; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: IPwnmQdiFuqF5+DyGJu613C16RSF/BucM5YlAgc8FQ/HmSXisfB6fjplbD+6mD2l2LzqqKSLqfpiun/UVKG6aC/v4W/hnIZcNQTcjIz7qfYcbleZkXIFwJwUTea0gqSKfFPH/uzEfq0qggr+2yf7RGS2ud04F2NwVoMlX5LzaH83pHZQGh20cVKuT5PRinwZE0Q4inCKew6/Zq2A4Awd087kNP/1oVgpE9wklI82Rr6FC3whj1dcwLWOFTMwNdJG6mwxKVSJoSypacOOTHxEg1PQOD+yK0SxGN27lghcu39bnM2B2RQwQzFc0fPml0lARu6dG4jrFSSjhyH10DSx3Q84mcMAL57uf7Zi3fKcsY4o/fVT1oZJARR/48AnDg7u x-forefront-antispam-report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:BYAPR11MB2856.namprd11.prod.outlook.com; PTR:; CAT:NONE; SFTY:; SFS:(376002)(136003)(366004)(346002)(39860400002)(396003)(478600001)(4326008)(2616005)(8676002)(91956017)(5660300002)(76116006)(66946007)(66476007)(66556008)(66446008)(64756008)(8936002)(31696002)(6512007)(186003)(26005)(6916009)(71200400001)(36756003)(2906002)(54906003)(6506007)(31686004)(53546011)(86362001)(6486002)(316002)(43740500002); DIR:OUT; SFP:1101; x-ms-exchange-antispam-messagedata: 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 x-ms-exchange-transport-forked: True Content-ID: <5C3A39E3AFA56B4E8784AD63F0BCBBBE@namprd11.prod.outlook.com> MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BYAPR11MB2856.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1d1ebaae-c21d-4b50-3399-08d82adc5431 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 Jul 2020 05:35:06.5568 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 3f4057f3-b418-4d4e-ba84-d55b4e897d88 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: XS/R/8Ngvl4VBj+DORn30stYEj55AUuDQpxJmLH9TcIVQzXBx5NnLZ4WQQvUy7/S83rDEG8bA8QZpsufHJL3tm27PPlQRR4lgRvrB1Z0LWw= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR11MB3575 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200718_013514_632199_5A0C01B7 X-CRM114-Status: GOOD ( 12.59 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: snelson@pensando.io, linux-mtd@lists.infradead.org, vigneshr@ti.com 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, David, On 7/17/20 9:00 PM, David Clear wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > On Fri, Jul 17, 2020 at 3:33 AM wrote: >> On 7/17/20 12:16 AM, David Clear wrote: >>> The Micron mt25qu02g supports both x2 and x4 transactions. Add the >>> SPI_NOR_DUAL_READ to its spi_nor_ids[] table entry. >> >> In spi_nor_select_read() we select the fastest read. Since this flash >> supports Quad Read, the Dual Read will never get selected. As of now, >> there is no benefit in adding SPI_NOR_DUAL_READ when SPI_NOR_QUAD_READ >> is specified. > > Ok, I've got this now: I went back and did some more testing with different > spi-rx-bus-width properties and I see it's redundant to specify both DUAL and > QUAD in the flash description. Thanks for pointing out my error. I learned > something new. > > I withdraw this patch and will work on getting the Macronix patch cleaned up and > tests documented. No, please keep this patch as well. You were right. If we remove the SPI_NOR_DUAL_READ flag, the dual read will work only because the SPI_NOR_QUAD_READ flag triggers the parsing of SFDP, which will fill the dual read caps. It is better to statically fill the 1-1-2 read, so that we can still use the dual read if SFDP parsing fails and will not fill the dual read caps. Let's keep it. Thanks, David. ta ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/