[PATCH v2 1/3] spi: Create a helper to derive adaptive timeouts
From: Miquel Raynal <miquel.raynal@bootlin.com>
Date: 2023-06-19 15:54:31
Also in:
linux-spi, linux-sunxi
Subsystem:
spi subsystem, the rest · Maintainers:
Mark Brown, Linus Torvalds
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
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