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Received: from bhuna.collabora.co.uk ([2a00:1098:0:82:1000:25:2eeb:e3e3]) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lj0YT-00EigL-4x; Tue, 18 May 2021 14:18:42 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 46DF61F4238F; Tue, 18 May 2021 15:18:37 +0100 (BST) Date: Tue, 18 May 2021 16:18:34 +0200 From: Boris Brezillon To: Cc: Mark Brown , Miquel Raynal , Vignesh Raghavendra , , Alexandre Torgue , , , , , Subject: Re: [PATCH v4 2/3] mtd: spinand: use the spi-mem poll status APIs Message-ID: <20210518161834.6860c310@collabora.com> In-Reply-To: <20210518134332.17826-3-patrice.chotard@foss.st.com> References: <20210518134332.17826-1-patrice.chotard@foss.st.com> <20210518134332.17826-3-patrice.chotard@foss.st.com> Organization: Collabora X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210518_071841_492418_E8833978 X-CRM114-Status: GOOD ( 30.65 ) 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 Tue, 18 May 2021 15:43:31 +0200 wrote: > From: Patrice Chotard > > Make use of spi-mem poll status APIs to let advanced controllers > optimize wait operations. > This should also fix the high CPU usage for system that don't have > a dedicated STATUS poll block logic. > > Signed-off-by: Patrice Chotard > Signed-off-by: Christophe Kerello > --- > Changes in v4: > - Update commit message. > - Add comment which explains how delays has been calculated. > - Rename SPINAND_STATUS_TIMEOUT_MS to SPINAND_WAITRDY_TIMEOUT_MS. > > Changes in v3: > - Add initial_delay_us and polling_delay_us parameters to spinand_wait() > - Add SPINAND_READ/WRITE/ERASE/RESET_INITIAL_DELAY_US and > SPINAND_READ/WRITE/ERASE/RESET_POLL_DELAY_US defines. > > Changes in v2: > - non-offload case is now managed by spi_mem_poll_status() > > drivers/mtd/nand/spi/core.c | 45 ++++++++++++++++++++++++++----------- > include/linux/mtd/spinand.h | 22 ++++++++++++++++++ > 2 files changed, 54 insertions(+), 13 deletions(-) > > diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c > index 17f63f95f4a2..3131fae0c715 100644 > --- a/drivers/mtd/nand/spi/core.c > +++ b/drivers/mtd/nand/spi/core.c > @@ -473,20 +473,26 @@ static int spinand_erase_op(struct spinand_device *spinand, > return spi_mem_exec_op(spinand->spimem, &op); > } > > -static int spinand_wait(struct spinand_device *spinand, u8 *s) > +static int spinand_wait(struct spinand_device *spinand, > + unsigned long initial_delay_us, > + unsigned long poll_delay_us, > + u8 *s) > { > - unsigned long timeo = jiffies + msecs_to_jiffies(400); > + struct spi_mem_op op = SPINAND_GET_FEATURE_OP(REG_STATUS, > + spinand->scratchbuf); > u8 status; > int ret; > > - do { > - ret = spinand_read_status(spinand, &status); > - if (ret) > - return ret; > + ret = spi_mem_poll_status(spinand->spimem, &op, STATUS_BUSY, 0, > + initial_delay_us, > + poll_delay_us, > + SPINAND_WAITRDY_TIMEOUT_MS); > + if (ret) > + return ret; > > - if (!(status & STATUS_BUSY)) > - goto out; > - } while (time_before(jiffies, timeo)); > + status = *spinand->scratchbuf; > + if (!(status & STATUS_BUSY)) > + goto out; Looks like you expect the driver to not only wait for a status change but also fill the data buffer with the last status value. I think that should be documented in the SPI mem API. > /* > * Extra read, just in case the STATUS_READY bit has changed > @@ -526,7 +532,10 @@ static int spinand_reset_op(struct spinand_device *spinand) > if (ret) > return ret; > > - return spinand_wait(spinand, NULL); > + return spinand_wait(spinand, > + SPINAND_RESET_INITIAL_DELAY_US, > + SPINAND_RESET_POLL_DELAY_US, > + NULL); > } > > static int spinand_lock_block(struct spinand_device *spinand, u8 lock) > @@ -549,7 +558,10 @@ static int spinand_read_page(struct spinand_device *spinand, > if (ret) > return ret; > > - ret = spinand_wait(spinand, &status); > + ret = spinand_wait(spinand, > + SPINAND_READ_INITIAL_DELAY_US, > + SPINAND_READ_POLL_DELAY_US, > + &status); > if (ret < 0) > return ret; > > @@ -585,7 +597,10 @@ static int spinand_write_page(struct spinand_device *spinand, > if (ret) > return ret; > > - ret = spinand_wait(spinand, &status); > + ret = spinand_wait(spinand, > + SPINAND_WRITE_INITIAL_DELAY_US, > + SPINAND_WRITE_POLL_DELAY_US, > + &status); > if (!ret && (status & STATUS_PROG_FAILED)) > return -EIO; > > @@ -768,7 +783,11 @@ static int spinand_erase(struct nand_device *nand, const struct nand_pos *pos) > if (ret) > return ret; > > - ret = spinand_wait(spinand, &status); > + ret = spinand_wait(spinand, > + SPINAND_ERASE_INITIAL_DELAY_US, > + SPINAND_ERASE_POLL_DELAY_US, > + &status); > + > if (!ret && (status & STATUS_ERASE_FAILED)) > ret = -EIO; > > diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h > index 6bb92f26833e..6988956b8492 100644 > --- a/include/linux/mtd/spinand.h > +++ b/include/linux/mtd/spinand.h > @@ -170,6 +170,28 @@ struct spinand_op; > struct spinand_device; > > #define SPINAND_MAX_ID_LEN 4 > +/* > + * For erase, write and read operation, we got the following timings : > + * tBERS (erase) 1ms to 4ms > + * tPROG 300us to 400us > + * tREAD 25us to 100us > + * In order to minimize latency, the min value is divided by 4 for the > + * initial delay, and dividing by 20 for the poll delay. > + * For reset, 5us/10us/500us if the device is respectively > + * reading/programming/erasing when the RESET occurs. Since we always > + * issue a RESET when the device is IDLE, 5us is selected for both initial > + * and poll delay. > + */ > +#define SPINAND_READ_INITIAL_DELAY_US 6 > +#define SPINAND_READ_POLL_DELAY_US 5 > +#define SPINAND_RESET_INITIAL_DELAY_US 5 > +#define SPINAND_RESET_POLL_DELAY_US 5 > +#define SPINAND_WRITE_INITIAL_DELAY_US 75 > +#define SPINAND_WRITE_POLL_DELAY_US 15 > +#define SPINAND_ERASE_INITIAL_DELAY_US 250 > +#define SPINAND_ERASE_POLL_DELAY_US 50 > + > +#define SPINAND_WAITRDY_TIMEOUT_MS 400 > > /** > * struct spinand_id - SPI NAND id structure _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel