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Mon, 17 May 2021 14:05:00 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id CB7D210002A; Mon, 17 May 2021 14:04:59 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag2node3.st.com [10.75.127.6]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id B78B722D625; Mon, 17 May 2021 14:04:59 +0200 (CEST) Received: from lmecxl0573.lme.st.com (10.75.127.49) by SFHDAG2NODE3.st.com (10.75.127.6) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 17 May 2021 14:04:58 +0200 Subject: Re: [PATCH v2 1/3] spi: spi-mem: add automatic poll status functions To: Boris Brezillon CC: Mark Brown , Miquel Raynal , Vignesh Raghavendra , , Alexandre Torgue , , , , , References: <20210507131756.17028-1-patrice.chotard@foss.st.com> <20210507131756.17028-2-patrice.chotard@foss.st.com> <20210517094140.53cb643a@collabora.com> <20210517132551.7dd56a5e@collabora.com> From: Patrice CHOTARD Message-ID: <45ee6378-271d-aeb5-90ea-ed2e0673f3fb@foss.st.com> Date: Mon, 17 May 2021 14:04:58 +0200 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: <20210517132551.7dd56a5e@collabora.com> Content-Language: en-US X-Originating-IP: [10.75.127.49] X-ClientProxiedBy: SFHDAG2NODE3.st.com (10.75.127.6) To SFHDAG2NODE3.st.com (10.75.127.6) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-05-17_04:2021-05-17, 2021-05-17 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210517_050505_327731_9C502F62 X-CRM114-Status: GOOD ( 31.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/17/21 1:25 PM, Boris Brezillon wrote: > On Mon, 17 May 2021 11:24:25 +0200 > Patrice CHOTARD wrote: > >> Hi Boris >> >> On 5/17/21 9:41 AM, Boris Brezillon wrote: >>> On Fri, 7 May 2021 15:17:54 +0200 >>> wrote: >>> >>>> +/** >>>> + * spi_mem_poll_status() - Poll memory device status >>>> + * @mem: SPI memory device >>>> + * @op: the memory operation to execute >>>> + * @mask: status bitmask to ckeck >>>> + * @match: (status & mask) expected value >>>> + * @timeout_ms: timeout in milliseconds >>>> + * >>>> + * This function send a polling status request to the controller driver >>>> + * >>>> + * Return: 0 in case of success, -ETIMEDOUT in case of error, >>>> + * -EOPNOTSUPP if not supported. >>>> + */ >>>> +int spi_mem_poll_status(struct spi_mem *mem, >>>> + const struct spi_mem_op *op, >>>> + u16 mask, u16 match, u16 timeout_ms) >>> >>> Maybe you should pass a delay_us too, to poll the status at the right >>> rate in the SW-based case (can also be used by drivers if they need to >> >> Ok, i will add a polling_rate_us parameter to poll_status() callback, >> even if in STM32 driver case we will not use it, i agree it should be useful >> depending of driver's implementation. >> >>> configure the polling rate). You could also add an initial_delay_us to >>> avoid polling the status too early: an erase operation will take longer >>> than a write which will take longer than a read. No need to check the >>> status just after issuing the command, especially if the polling is >>> done in SW. Those 2 arguments should also be passed to the driver. >> >> Regarding the addition of an initial_delay_us. We got two solution: >> - use the same polling rate already used by read_poll_timeout() and >> set read_poll_timeout()'s sleep_before_read parameter to true (in our case 20 us >> will be used as initial delay and as polling rate). >> >> - add an udelay(initial_delay_us) or even better usleep_range(initial_delay_us, >> initial_delay_us + delta) before calling read_poll_timeout(). >> >> I imagine you prefer the second solution ? > > Yep, you might want to use udelay() when the delay is small and > usleep_range() otherwise. > >> >> By adding polling_rate_us and initial_delay_us parameters to >> spi_mem_poll_status(), it implies to update all spinand_wait() calls for >> different operations (reset, read page, write page, erase) with respective >> initial_delay_us/polling_rate_us values for spi_mem_poll_status()'s parameters. >> >> Can you provide adequate initial_delay_us and polling rate_us for each operation type ?. > > If I refer to the datasheets I have, > > tBERS (erase) 1ms to 4ms > tPROG 300us to 400us > tREAD 25us to 100us > > Let's assume we want to minimize the latency, I'd recommend dividing > the min value by 4 for the initial delay, and dividing it by 20 for the > poll delay, which gives: > > ERASE -> initial_delay = 250us, poll_delay = 50us > PROG -> initial_delay = 100us, poll_delay = 20us another remark, it should be: PROG -> initial_delay = 75 us (300 / 4) , poll_delay = 15us ( 300 / 20) Patrice > READ -> initial_delay = 6us, poll_delay = 5us > > Of course, that'd be even better if we were able to extract this > information from the NAND ID (or ONFI table), but I guess we can live > with those optimistic values in the meantime. > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel