From: Miquel Raynal <miquel.raynal@bootlin.com> To: Mark Brown <broonie@kernel.org>, <linux-spi@vger.kernel.org> Cc: 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>, Claudiu Beznea <claudiu.beznea@microchip.com>, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 2/3] spi: atmel: Prevent false timeouts on long transfers Date: Thu, 22 Jun 2023 11:06:33 +0200 [thread overview] Message-ID: <20230622090634.3411468-3-miquel.raynal@bootlin.com> (raw) In-Reply-To: <20230622090634.3411468-1-miquel.raynal@bootlin.com> A slow SPI bus clocks at ~20MHz, which means it would transfer about 2500 bytes per second with a single data line. Big transfers, like when dealing with flashes can easily reach a few MiB. The current DMA timeout is set to 1 second, which means any working transfer of about 4MiB will always be cancelled. With the above derivations, on a slow bus, we can assume every byte will take at most 0.4ms. Said otherwise, we could add 4ms to the 1-second timeout delay every 10kiB. On a 4MiB transfer, it would bring the timeout delay up to 2.6s which still seems rather acceptable for a timeout. The consequence of this is that long transfers might be allowed, which hence requires the need to interrupt the transfer if wanted by the user. We can hence switch to the _interruptible variant of wait_for_completion. This leads to a little bit more handling to also handle the interrupted case but looks really acceptable overall. While at it, we drop the useless, noisy and redundant WARN_ON() call. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- drivers/spi/spi-atmel.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 943548aab8af..d87be2890597 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -233,7 +233,8 @@ */ #define DMA_MIN_BYTES 16 -#define SPI_DMA_TIMEOUT (msecs_to_jiffies(1000)) +#define SPI_DMA_MIN_TIMEOUT (msecs_to_jiffies(1000)) +#define SPI_DMA_TIMEOUT_PER_10K (msecs_to_jiffies(4)) #define AUTOSUSPEND_TIMEOUT 2000 @@ -1279,7 +1280,8 @@ static int atmel_spi_one_transfer(struct spi_controller *host, struct atmel_spi_device *asd; int timeout; int ret; - unsigned long dma_timeout; + unsigned int dma_timeout; + long ret_timeout; as = spi_controller_get_devdata(host); @@ -1333,11 +1335,13 @@ static int atmel_spi_one_transfer(struct spi_controller *host, atmel_spi_unlock(as); } - dma_timeout = wait_for_completion_timeout(&as->xfer_completion, - SPI_DMA_TIMEOUT); - if (WARN_ON(dma_timeout == 0)) { - dev_err(&spi->dev, "spi transfer timeout\n"); - as->done_status = -EIO; + dma_timeout = msecs_to_jiffies(spi_controller_xfer_timeout(host, xfer)); + ret_timeout = wait_for_completion_interruptible_timeout(&as->xfer_completion, + dma_timeout); + if (ret_timeout <= 0) { + dev_err(&spi->dev, "spi transfer %s\n", + !ret_timeout ? "timeout" : "canceled"); + as->done_status = ret_timeout < 0 ? ret_timeout : -EIO; } if (as->done_status) -- 2.34.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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: Thomas Petazzoni <thomas.petazzoni@bootlin.com>, Tudor Ambarus <tudor.ambarus@linaro.org>, Nicolas Ferre <nicolas.ferre@microchip.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>, Miquel Raynal <miquel.raynal@bootlin.com> Subject: [PATCH v3 2/3] spi: atmel: Prevent false timeouts on long transfers Date: Thu, 22 Jun 2023 11:06:33 +0200 [thread overview] Message-ID: <20230622090634.3411468-3-miquel.raynal@bootlin.com> (raw) In-Reply-To: <20230622090634.3411468-1-miquel.raynal@bootlin.com> A slow SPI bus clocks at ~20MHz, which means it would transfer about 2500 bytes per second with a single data line. Big transfers, like when dealing with flashes can easily reach a few MiB. The current DMA timeout is set to 1 second, which means any working transfer of about 4MiB will always be cancelled. With the above derivations, on a slow bus, we can assume every byte will take at most 0.4ms. Said otherwise, we could add 4ms to the 1-second timeout delay every 10kiB. On a 4MiB transfer, it would bring the timeout delay up to 2.6s which still seems rather acceptable for a timeout. The consequence of this is that long transfers might be allowed, which hence requires the need to interrupt the transfer if wanted by the user. We can hence switch to the _interruptible variant of wait_for_completion. This leads to a little bit more handling to also handle the interrupted case but looks really acceptable overall. While at it, we drop the useless, noisy and redundant WARN_ON() call. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- drivers/spi/spi-atmel.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 943548aab8af..d87be2890597 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -233,7 +233,8 @@ */ #define DMA_MIN_BYTES 16 -#define SPI_DMA_TIMEOUT (msecs_to_jiffies(1000)) +#define SPI_DMA_MIN_TIMEOUT (msecs_to_jiffies(1000)) +#define SPI_DMA_TIMEOUT_PER_10K (msecs_to_jiffies(4)) #define AUTOSUSPEND_TIMEOUT 2000 @@ -1279,7 +1280,8 @@ static int atmel_spi_one_transfer(struct spi_controller *host, struct atmel_spi_device *asd; int timeout; int ret; - unsigned long dma_timeout; + unsigned int dma_timeout; + long ret_timeout; as = spi_controller_get_devdata(host); @@ -1333,11 +1335,13 @@ static int atmel_spi_one_transfer(struct spi_controller *host, atmel_spi_unlock(as); } - dma_timeout = wait_for_completion_timeout(&as->xfer_completion, - SPI_DMA_TIMEOUT); - if (WARN_ON(dma_timeout == 0)) { - dev_err(&spi->dev, "spi transfer timeout\n"); - as->done_status = -EIO; + dma_timeout = msecs_to_jiffies(spi_controller_xfer_timeout(host, xfer)); + ret_timeout = wait_for_completion_interruptible_timeout(&as->xfer_completion, + dma_timeout); + if (ret_timeout <= 0) { + dev_err(&spi->dev, "spi transfer %s\n", + !ret_timeout ? "timeout" : "canceled"); + as->done_status = ret_timeout < 0 ? ret_timeout : -EIO; } if (as->done_status) -- 2.34.1
next prev parent reply other threads:[~2023-06-22 9:07 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-22 9:06 [PATCH v3 0/3] spi: Helper for deriving timeout values Miquel Raynal 2023-06-22 9:06 ` Miquel Raynal 2023-06-22 9:06 ` [PATCH v3 1/3] spi: Create a helper to derive adaptive timeouts Miquel Raynal 2023-06-22 9:06 ` Miquel Raynal 2023-06-22 9:06 ` Miquel Raynal [this message] 2023-06-22 9:06 ` [PATCH v3 2/3] spi: atmel: Prevent false timeouts on long transfers Miquel Raynal 2023-06-22 16:29 ` Ryan.Wanner 2023-06-22 16:29 ` Ryan.Wanner 2023-06-22 9:06 ` [PATCH v3 3/3] spi: sun6i: Use the new helper to derive the xfer timeout value Miquel Raynal 2023-06-22 9:06 ` Miquel Raynal 2023-06-22 16:46 ` [PATCH v3 0/3] spi: Helper for deriving timeout values Jernej Škrabec 2023-06-22 16:46 ` Jernej Škrabec 2023-06-22 21:18 ` Miquel Raynal 2023-06-22 21:18 ` Miquel Raynal 2023-06-23 0:32 ` Mark Brown 2023-06-23 0:32 ` Mark Brown
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