From: kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org To: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Eric Anholt <eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org>, Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Subject: [PATCH 3/3] spi: bcm2835: add module parameter to configure minimum length for dma Date: Sun, 24 Feb 2019 16:23:11 +0000 [thread overview] Message-ID: <20190224162311.23899-3-kernel@martin.sperl.org> (raw) In-Reply-To: <20190224162311.23899-1-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> Allow setting the length of the transfer at which dma is used by setting a module parameter. Signed-off-by: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> --- drivers/spi/spi-bcm2835.c | 40 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 37 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index dcf922ca2603..ef4b3468a97d 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -31,6 +31,7 @@ #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> +#include <linux/moduleparam.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_device.h> @@ -44,6 +45,39 @@ module_param(polling_limit_us, uint, 0664); MODULE_PARM_DESC(polling_limit_us, "time in us to run a transfer in polling mode\n"); +/* define dma min number of bytes to use in dma mode with value validation */ +static int dma_min_bytes_limit_set(const char *val, + const struct kernel_param *kp) +{ + unsigned int v; + + if (kstrtouint(val, 10, &v)) + return -EINVAL; + /* value needs to be a multiple of 4 */ + if (v % 4) { + pr_err("dma_min_bytes_limit needs to be a multiple of 4\n"); + return -EINVAL; + } + /* value needs to be at least 6 - so actually 8 - rational below */ + if (v < 6) { + pr_err("dma_min_bytes_limit needs to be at least 8\n"); + return -EINVAL; + } + + return param_set_uint(val, kp); +} + +static const struct kernel_param_ops dma_min_bytes_limit_ops = { + .set = dma_min_bytes_limit_set, + .get = param_get_int, +}; + +unsigned int dma_min_bytes_limit = 96; +module_param_cb(dma_min_bytes_limit, &dma_min_bytes_limit_ops, + &dma_min_bytes_limit, 0664); +MODULE_PARM_DESC(dma_min_bytes_limit, + "minimum number of bytes to run a transfer in dma mode\n"); + /* SPI register offsets */ #define BCM2835_SPI_CS 0x00 #define BCM2835_SPI_FIFO 0x04 @@ -80,7 +114,6 @@ MODULE_PARM_DESC(polling_limit_us, #define BCM2835_SPI_FIFO_SIZE 64 #define BCM2835_SPI_FIFO_SIZE_3_4 48 -#define BCM2835_SPI_DMA_MIN_LENGTH 96 #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \ | SPI_NO_CS | SPI_3WIRE) @@ -447,7 +480,8 @@ static int bcm2835_spi_transfer_one_irq(struct spi_master *master, * if the length of the first is *exactly* 1. * * At most 6 bytes are written and at most 3 bytes read. Do we know the - * transfer has this many bytes? Yes, see BCM2835_SPI_DMA_MIN_LENGTH. + * transfer has this many bytes? Yes, see validation in + * dma_min_bytes_limit_set. * * The FIFO is normally accessed with 8-bit width by the CPU and 32-bit width * by the DMA engine. Toggling the DMA Enable flag in the CS register switches @@ -690,7 +724,7 @@ static bool bcm2835_spi_can_dma(struct spi_master *master, struct spi_transfer *tfr) { /* we start DMA efforts only on bigger transfers */ - if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH) + if (tfr->len < dma_min_bytes_limit) return false; /* BCM2835_SPI_DLEN has defined a max transfer size as -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: kernel@martin.sperl.org To: Mark Brown <broonie@kernel.org>, Eric Anholt <eric@anholt.net>, Stefan Wahren <stefan.wahren@i2se.com>, linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Cc: Martin Sperl <kernel@martin.sperl.org> Subject: [PATCH 3/3] spi: bcm2835: add module parameter to configure minimum length for dma Date: Sun, 24 Feb 2019 16:23:11 +0000 [thread overview] Message-ID: <20190224162311.23899-3-kernel@martin.sperl.org> (raw) In-Reply-To: <20190224162311.23899-1-kernel@martin.sperl.org> From: Martin Sperl <kernel@martin.sperl.org> Allow setting the length of the transfer at which dma is used by setting a module parameter. Signed-off-by: Martin Sperl <kernel@martin.sperl.org> --- drivers/spi/spi-bcm2835.c | 40 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 37 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index dcf922ca2603..ef4b3468a97d 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -31,6 +31,7 @@ #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> +#include <linux/moduleparam.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_device.h> @@ -44,6 +45,39 @@ module_param(polling_limit_us, uint, 0664); MODULE_PARM_DESC(polling_limit_us, "time in us to run a transfer in polling mode\n"); +/* define dma min number of bytes to use in dma mode with value validation */ +static int dma_min_bytes_limit_set(const char *val, + const struct kernel_param *kp) +{ + unsigned int v; + + if (kstrtouint(val, 10, &v)) + return -EINVAL; + /* value needs to be a multiple of 4 */ + if (v % 4) { + pr_err("dma_min_bytes_limit needs to be a multiple of 4\n"); + return -EINVAL; + } + /* value needs to be at least 6 - so actually 8 - rational below */ + if (v < 6) { + pr_err("dma_min_bytes_limit needs to be at least 8\n"); + return -EINVAL; + } + + return param_set_uint(val, kp); +} + +static const struct kernel_param_ops dma_min_bytes_limit_ops = { + .set = dma_min_bytes_limit_set, + .get = param_get_int, +}; + +unsigned int dma_min_bytes_limit = 96; +module_param_cb(dma_min_bytes_limit, &dma_min_bytes_limit_ops, + &dma_min_bytes_limit, 0664); +MODULE_PARM_DESC(dma_min_bytes_limit, + "minimum number of bytes to run a transfer in dma mode\n"); + /* SPI register offsets */ #define BCM2835_SPI_CS 0x00 #define BCM2835_SPI_FIFO 0x04 @@ -80,7 +114,6 @@ MODULE_PARM_DESC(polling_limit_us, #define BCM2835_SPI_FIFO_SIZE 64 #define BCM2835_SPI_FIFO_SIZE_3_4 48 -#define BCM2835_SPI_DMA_MIN_LENGTH 96 #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \ | SPI_NO_CS | SPI_3WIRE) @@ -447,7 +480,8 @@ static int bcm2835_spi_transfer_one_irq(struct spi_master *master, * if the length of the first is *exactly* 1. * * At most 6 bytes are written and at most 3 bytes read. Do we know the - * transfer has this many bytes? Yes, see BCM2835_SPI_DMA_MIN_LENGTH. + * transfer has this many bytes? Yes, see validation in + * dma_min_bytes_limit_set. * * The FIFO is normally accessed with 8-bit width by the CPU and 32-bit width * by the DMA engine. Toggling the DMA Enable flag in the CS register switches @@ -690,7 +724,7 @@ static bool bcm2835_spi_can_dma(struct spi_master *master, struct spi_transfer *tfr) { /* we start DMA efforts only on bigger transfers */ - if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH) + if (tfr->len < dma_min_bytes_limit) return false; /* BCM2835_SPI_DLEN has defined a max transfer size as -- 2.11.0 _______________________________________________ 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:[~2019-02-24 16:23 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-24 16:23 [PATCH 1/3] spi: bcm2835: add driver stats to debugfs kernel-TqfNSX0MhmxHKSADF0wUEw 2019-02-24 16:23 ` kernel [not found] ` <20190224162311.23899-1-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> 2019-02-24 16:23 ` [PATCH 2/3] spi: bcm2835: avoid 64 bit arithmetic and allow to configure polling limit kernel-TqfNSX0MhmxHKSADF0wUEw 2019-02-24 16:23 ` kernel 2019-02-24 16:23 ` kernel-TqfNSX0MhmxHKSADF0wUEw [this message] 2019-02-24 16:23 ` [PATCH 3/3] spi: bcm2835: add module parameter to configure minimum length for dma kernel [not found] ` <20190224162311.23899-3-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> 2019-02-24 19:10 ` Stefan Wahren 2019-02-24 19:10 ` Stefan Wahren 2019-03-24 8:52 ` kernel 2019-03-24 8:52 ` kernel [not found] ` <20190324101552.brc7ojrfrsgyr77d@wunner.de> 2019-03-24 11:23 ` kernel [not found] ` <20190322123610.ndwxoivsprc643f5@wunner.de> [not found] ` <20190322123610.ndwxoivsprc643f5-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> 2019-03-24 8:58 ` kernel-TqfNSX0MhmxHKSADF0wUEw 2019-03-24 8:58 ` kernel
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