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Sat, 3 Oct 2020 06:40:14 -0500 Received: from DLEE105.ent.ti.com (157.170.170.35) by DLEE115.ent.ti.com (157.170.170.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Sat, 3 Oct 2020 06:40:13 -0500 Received: from lelv0327.itg.ti.com (10.180.67.183) by DLEE105.ent.ti.com (157.170.170.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3 via Frontend Transport; Sat, 3 Oct 2020 06:40:13 -0500 Received: from [10.250.235.166] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id 093Be9LR090992; Sat, 3 Oct 2020 06:40:10 -0500 Subject: Re: [PATCH v15 14/15] mtd: spi-nor: spansion: add support for Cypress Semper flash To: Pratyush Yadav , Tudor Ambarus , Miquel Raynal , Richard Weinberger , , References: <20201001202045.21499-1-p.yadav@ti.com> <20201001202045.21499-15-p.yadav@ti.com> From: Vignesh Raghavendra Message-ID: <6690e22f-b2e4-7c89-397c-2c1aafb0339a@ti.com> Date: Sat, 3 Oct 2020 17:10:09 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201001202045.21499-15-p.yadav@ti.com> Content-Language: en-US X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201003_074023_078144_3B0F4C5E X-CRM114-Status: GOOD ( 19.84 ) 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: Boris Brezillon , Sekhar Nori 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 Pratyush, On 10/2/20 1:50 AM, Pratyush Yadav wrote: > + > +/** > + * spi_nor_cypress_octal_dtr_enable() - Enable octal DTR on Cypress flashes. > + * @nor: pointer to a 'struct spi_nor' > + * @enable: whether to enable or disable Octal DTR > + * > + * This also sets the memory access latency cycles to 24 to allow the flash to > + * run at up to 200MHz. > + * > + * Return: 0 on success, -errno otherwise. > + */ > +static int spi_nor_cypress_octal_dtr_enable(struct spi_nor *nor, bool enable) > +{ > + struct spi_mem_op op; > + u8 *buf = nor->bouncebuf; > + int ret; > + > + if (enable) { > + /* Use 24 dummy cycles for memory array reads. */ > + ret = spi_nor_write_enable(nor); > + if (ret) > + return ret; > + > + *buf = SPINOR_REG_CYPRESS_CFR2V_MEMLAT_11_24; > + op = (struct spi_mem_op) > + SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WR_ANY_REG, 1), > + SPI_MEM_OP_ADDR(3, SPINOR_REG_CYPRESS_CFR2V, > + 1), > + SPI_MEM_OP_NO_DUMMY, > + SPI_MEM_OP_DATA_OUT(1, buf, 1)); > + > + ret = spi_mem_exec_op(nor->spimem, &op); > + if (ret) > + return ret; > + > + ret = spi_nor_wait_till_ready(nor); > + if (ret) > + return ret; > + > + nor->read_dummy = 24; > + } > + > + /* Set/unset the octal and DTR enable bits. */ > + ret = spi_nor_write_enable(nor); > + if (ret) > + return ret; > + > + if (enable) > + *buf = SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_EN; > + else > + *buf = SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_DS; > + > + op = (struct spi_mem_op) > + SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WR_ANY_REG, 1), > + SPI_MEM_OP_ADDR(enable ? 3 : 4, > + SPINOR_REG_CYPRESS_CFR5V, > + 1), > + SPI_MEM_OP_NO_DUMMY, > + SPI_MEM_OP_DATA_OUT(1, buf, 1)); > + > + if (!enable) > + spi_nor_spimem_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR); > + > + ret = spi_mem_exec_op(nor->spimem, &op); > + if (ret) > + return ret; > + > + /* Give some time for the mode change to take place. */ > + usleep_range(1000, 1500); > + According to datasheet, it seems switch to Octal DTR mode is immediate. So, I don't think this delay is necessary. Instead as a confirmation that mode switch is successful can we just read back SPINOR_REG_CYPRESS_CFR5V in Octal DTR mode and see if value reflects what was written? Same applies for 15/15 as well. > + return 0; > +} > + ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/