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Wed, 30 Sep 2020 02:43:11 -0500 Received: from DFLE102.ent.ti.com (10.64.6.23) by DFLE109.ent.ti.com (10.64.6.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Wed, 30 Sep 2020 02:43:11 -0500 Received: from fllv0039.itg.ti.com (10.64.41.19) by DFLE102.ent.ti.com (10.64.6.23) 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; Wed, 30 Sep 2020 02:43:11 -0500 Received: from localhost (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 08U7hAoo074277; Wed, 30 Sep 2020 02:43:11 -0500 Date: Wed, 30 Sep 2020 13:13:09 +0530 From: Pratyush Yadav To: Subject: Re: [PATCH v13 11/15] mtd: spi-nor: core: perform a Soft Reset on shutdown Message-ID: <20200930074307.rdi6352fy3is6gjq@ti.com> References: <20200916124418.833-1-p.yadav@ti.com> <20200916124418.833-12-p.yadav@ti.com> <20200929130838.4hfa2y3qoxissdus@ti.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20171215 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-20200930_034316_948724_081FE09C X-CRM114-Status: GOOD ( 31.66 ) 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: vigneshr@ti.com, richard@nod.at, nsekhar@ti.com, linux-kernel@vger.kernel.org, boris.brezillon@collabora.com, linux-mtd@lists.infradead.org, miquel.raynal@bootlin.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 On 30/09/20 07:32AM, Tudor.Ambarus@microchip.com wrote: > On 9/29/20 4:08 PM, Pratyush Yadav wrote: > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > > > On 16/09/20 06:14PM, Pratyush Yadav wrote: > >> Perform a Soft Reset on shutdown on flashes that support it so that the > >> flash can be reset to its initial state and any configurations made by > >> spi-nor (given that they're only done in volatile registers) will be > >> reset. This will hand back the flash in pristine state for any further > >> operations on it. > >> > >> Signed-off-by: Pratyush Yadav > >> --- > >> drivers/mtd/spi-nor/core.c | 41 +++++++++++++++++++++++++++++++++++++ > >> include/linux/mtd/spi-nor.h | 2 ++ > >> 2 files changed, 43 insertions(+) > >> > >> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c > >> index 6ee93544d72f..853dfa02f0de 100644 > >> --- a/drivers/mtd/spi-nor/core.c > >> +++ b/drivers/mtd/spi-nor/core.c > >> @@ -40,6 +40,9 @@ > >> > >> #define SPI_NOR_MAX_ADDR_WIDTH 4 > >> > >> +#define SPI_NOR_SRST_SLEEP_MIN 200 > >> +#define SPI_NOR_SRST_SLEEP_MAX 400 > >> + > >> /** > >> * spi_nor_get_cmd_ext() - Get the command opcode extension based on the > >> * extension type. > >> @@ -3174,6 +3177,41 @@ static int spi_nor_init(struct spi_nor *nor) > >> return 0; > >> } > >> > >> +static void spi_nor_soft_reset(struct spi_nor *nor) > >> +{ > >> + struct spi_mem_op op; > >> + int ret; > >> + > >> + op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRSTEN, 8), > > can we avoid the cast? No. The compiler complains about "expected expression before '{' token". We can avoid it if the assignment is with the declaration but then we can't re-use the variable op for the second command. I like the cast better than using separate variables for the two (or more in other cases) commands we execute. > > > > The buswidth used here should be 1 instead of 8. It makes no difference > > in practice because the call to spi_nor_spimem_setup_op() immediately > > after will over-write it to the correct value anyway, but let's follow > > the style followed throughout the rest of the codebase. Will fix in the > > next version. > > or you can just set the buswidth to 0 so that the reader rises his eyebrow > and search for where it is updated. If you like it better you'll have to change > throughout the entire code base, maybe in 4/15 where setup_op is introduced. Ok. Will change it. > > > >> + SPI_MEM_OP_NO_DUMMY, > >> + SPI_MEM_OP_NO_ADDR, > >> + SPI_MEM_OP_NO_DATA); > >> + spi_nor_spimem_setup_op(nor, &op, nor->reg_proto); > > Still not a big fan of this, but we can update the op init later on. How > about some new lines around spi_nor_spimem_setup_op()? First time I read > the code I haven't seen it. Ok. > >> + ret = spi_mem_exec_op(nor->spimem, &op); > >> + if (ret) { > >> + dev_warn(nor->dev, "Software reset failed: %d\n", ret); > >> + return; > >> + } > >> + > >> + op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRST, 8), > > > > Same here. > > > >> + SPI_MEM_OP_NO_DUMMY, > >> + SPI_MEM_OP_NO_ADDR, > >> + SPI_MEM_OP_NO_DATA); > >> + spi_nor_spimem_setup_op(nor, &op, nor->reg_proto); > >> + ret = spi_mem_exec_op(nor->spimem, &op); > >> + if (ret) { > >> + dev_warn(nor->dev, "Software reset failed: %d\n", ret); > >> + return; > >> + } > >> + > >> + /* > >> + * Software Reset is not instant, and the delay varies from flash to > >> + * flash. Looking at a few flashes, most range somewhere below 100 > >> + * microseconds. So, sleep for a range of 200-400 us. > >> + */ > >> + usleep_range(SPI_NOR_SRST_SLEEP_MIN, SPI_NOR_SRST_SLEEP_MAX); > >> +} > >> + > >> /* mtd resume handler */ > >> static void spi_nor_resume(struct mtd_info *mtd) > >> { -- Regards, Pratyush Yadav Texas Instruments India ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/