From: Miquel Raynal <miquel.raynal@bootlin.com> To: Mark Brown <broonie@kernel.org>, <linux-spi@vger.kernel.org> Cc: Tudor Ambarus <tudor.ambarus@linaro.org>, Thomas Petazzoni <thomas.petazzoni@bootlin.com>, Nicolas Ferre <nicolas.ferre@microchip.com>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Claudiu Beznea <claudiu.beznea@microchip.com>, Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@gmail.com>, Samuel Holland <samuel@sholland.org>, <linux-arm-kernel@lists.infradead.org>, linux-sunxi@lists.linux.dev, Miquel Raynal <miquel.raynal@bootlin.com> Subject: [PATCH v2 1/3] spi: Create a helper to derive adaptive timeouts Date: Mon, 19 Jun 2023 17:53:47 +0200 [thread overview] Message-ID: <20230619155349.3118420-2-miquel.raynal@bootlin.com> (raw) In-Reply-To: <20230619155349.3118420-1-miquel.raynal@bootlin.com> Big transfers might take a bit of time, too constraining timeouts might lead to false positives. In order to simplify the drivers work and with the goal of factorizing code in mind, let's add a helper that can be used by any spi controller driver to derive a relevant per-transfer timeout value. The logic is simple: we know how much time it would take to transfer a byte, we can easily derive the total theoretical amount of time involved for each transfer. We multiply it by two to have a bit of margin and enforce a minimum of 500ms. Suggested-by: Mark Brown <broonie@kernel.org> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- include/linux/spi/spi.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index fbf8c0d95968..4d6636c50465 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -1186,6 +1186,23 @@ static inline bool spi_is_bpw_supported(struct spi_device *spi, u32 bpw) return false; } +/** + * spi_controller_xfer_timeout - Compute a suitable timeout value + * @ctlr: SPI device + * @xfer: Transfer descriptor + * + * Compute a relevant timeout value for the given transfer. We derive the time + * that it would take on a single data line and take twice this amount of time + * with a minimum of 500ms to avoid false positives on loaded systems. + * + * Returns: Transfer timeout value in milliseconds. + */ +static inline unsigned int spi_controller_xfer_timeout(struct spi_controller *ctlr, + struct spi_transfer *xfer) +{ + return max(xfer->len * 8 * 2 / (xfer->speed_hz / 1000), 500U); +} + /*---------------------------------------------------------------------------*/ /* SPI transfer replacement methods which make use of spi_res */ -- 2.34.1
WARNING: multiple messages have this Message-ID (diff)
From: Miquel Raynal <miquel.raynal@bootlin.com> To: Mark Brown <broonie@kernel.org>, <linux-spi@vger.kernel.org> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>, Samuel Holland <samuel@sholland.org>, Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@gmail.com>, Tudor Ambarus <tudor.ambarus@linaro.org>, Thomas Petazzoni <thomas.petazzoni@bootlin.com>, Miquel Raynal <miquel.raynal@bootlin.com>, linux-sunxi@lists.linux.dev, Claudiu Beznea <claudiu.beznea@microchip.com>, linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 1/3] spi: Create a helper to derive adaptive timeouts Date: Mon, 19 Jun 2023 17:53:47 +0200 [thread overview] Message-ID: <20230619155349.3118420-2-miquel.raynal@bootlin.com> (raw) In-Reply-To: <20230619155349.3118420-1-miquel.raynal@bootlin.com> Big transfers might take a bit of time, too constraining timeouts might lead to false positives. In order to simplify the drivers work and with the goal of factorizing code in mind, let's add a helper that can be used by any spi controller driver to derive a relevant per-transfer timeout value. The logic is simple: we know how much time it would take to transfer a byte, we can easily derive the total theoretical amount of time involved for each transfer. We multiply it by two to have a bit of margin and enforce a minimum of 500ms. Suggested-by: Mark Brown <broonie@kernel.org> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- include/linux/spi/spi.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index fbf8c0d95968..4d6636c50465 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -1186,6 +1186,23 @@ static inline bool spi_is_bpw_supported(struct spi_device *spi, u32 bpw) return false; } +/** + * spi_controller_xfer_timeout - Compute a suitable timeout value + * @ctlr: SPI device + * @xfer: Transfer descriptor + * + * Compute a relevant timeout value for the given transfer. We derive the time + * that it would take on a single data line and take twice this amount of time + * with a minimum of 500ms to avoid false positives on loaded systems. + * + * Returns: Transfer timeout value in milliseconds. + */ +static inline unsigned int spi_controller_xfer_timeout(struct spi_controller *ctlr, + struct spi_transfer *xfer) +{ + return max(xfer->len * 8 * 2 / (xfer->speed_hz / 1000), 500U); +} + /*---------------------------------------------------------------------------*/ /* SPI transfer replacement methods which make use of spi_res */ -- 2.34.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-06-19 15:54 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-19 15:53 [PATCH v2 0/3] spi: Helper for deriving timeout values Miquel Raynal 2023-06-19 15:53 ` Miquel Raynal 2023-06-19 15:53 ` Miquel Raynal [this message] 2023-06-19 15:53 ` [PATCH v2 1/3] spi: Create a helper to derive adaptive timeouts Miquel Raynal 2023-06-19 15:53 ` [PATCH v2 2/3] spi: atmel: Prevent false timeouts on long transfers Miquel Raynal 2023-06-19 15:53 ` Miquel Raynal 2023-06-21 14:59 ` Mark Brown 2023-06-21 14:59 ` Mark Brown 2023-06-22 8:25 ` Miquel Raynal 2023-06-22 8:25 ` Miquel Raynal 2023-06-19 15:53 ` [PATCH v2 3/3] spi: sun6i: Use the new helper to derive the xfer timeout value Miquel Raynal 2023-06-19 15:53 ` Miquel Raynal 2023-06-21 15:51 ` Jernej Škrabec 2023-06-21 15:51 ` Jernej Škrabec 2023-06-26 16:47 ` [PATCH v2 0/3] spi: Helper for deriving timeout values Mark Brown 2023-06-26 16:47 ` Mark Brown
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20230619155349.3118420-2-miquel.raynal@bootlin.com \ --to=miquel.raynal@bootlin.com \ --cc=alexandre.belloni@bootlin.com \ --cc=broonie@kernel.org \ --cc=claudiu.beznea@microchip.com \ --cc=jernej.skrabec@gmail.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-spi@vger.kernel.org \ --cc=linux-sunxi@lists.linux.dev \ --cc=nicolas.ferre@microchip.com \ --cc=samuel@sholland.org \ --cc=thomas.petazzoni@bootlin.com \ --cc=tudor.ambarus@linaro.org \ --cc=wens@csie.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.