diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.1/0155-spi-bcm2835-fallback-to-interrupt-for-polling-timeou.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.1/0155-spi-bcm2835-fallback-to-interrupt-for-polling-timeou.patch | 136 |
1 files changed, 0 insertions, 136 deletions
diff --git a/target/linux/brcm2708/patches-4.1/0155-spi-bcm2835-fallback-to-interrupt-for-polling-timeou.patch b/target/linux/brcm2708/patches-4.1/0155-spi-bcm2835-fallback-to-interrupt-for-polling-timeou.patch deleted file mode 100644 index 01612e53af..0000000000 --- a/target/linux/brcm2708/patches-4.1/0155-spi-bcm2835-fallback-to-interrupt-for-polling-timeou.patch +++ /dev/null @@ -1,136 +0,0 @@ -From 4a42130b7fe39652a3ed8ced413a71c7f5d7ce61 Mon Sep 17 00:00:00 2001 -From: Martin Sperl <kernel@martin.sperl.org> -Date: Wed, 22 Apr 2015 07:33:03 +0000 -Subject: [PATCH 155/222] spi: bcm2835: fallback to interrupt for polling - timeouts exceeding 2 jiffies - -The polling mode of the driver is designed for transfers that run -less than 30us - it will only execute under those circumstances. -So it should run comfortably without getting interrupted by the -scheduler. - -But there are situations where the raspberry pi is so overloaded -that it can take up to 80 jiffies until the polling thread gets -rescheduled - this has been observed especially under heavy -IO situations. - -In such a situation we now fall back to the interrupt handler and -log the situation at debug level. - -Signed-off-by: Martin Sperl <kernel@martin.sperl.org> -Signed-off-by: Mark Brown <broonie@kernel.org> -(cherry picked from commit a750b124cfd27bae1a12df22318db5a2083dfb12) ---- - drivers/spi/spi-bcm2835.c | 87 +++++++++++++++++++++++++++-------------------- - 1 file changed, 50 insertions(+), 37 deletions(-) - ---- a/drivers/spi/spi-bcm2835.c -+++ b/drivers/spi/spi-bcm2835.c -@@ -69,7 +69,7 @@ - #define BCM2835_SPI_CS_CS_01 0x00000001 - - #define BCM2835_SPI_POLLING_LIMIT_US 30 --#define BCM2835_SPI_TIMEOUT_MS 30000 -+#define BCM2835_SPI_POLLING_JIFFIES 2 - #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \ - | SPI_NO_CS | SPI_3WIRE) - -@@ -157,42 +157,6 @@ static irqreturn_t bcm2835_spi_interrupt - return IRQ_HANDLED; - } - --static int bcm2835_spi_transfer_one_poll(struct spi_master *master, -- struct spi_device *spi, -- struct spi_transfer *tfr, -- u32 cs, -- unsigned long xfer_time_us) --{ -- struct bcm2835_spi *bs = spi_master_get_devdata(master); -- /* set timeout to 1 second of maximum polling */ -- unsigned long timeout = jiffies + HZ; -- -- /* enable HW block without interrupts */ -- bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA); -- -- /* loop until finished the transfer */ -- while (bs->rx_len) { -- /* read from fifo as much as possible */ -- bcm2835_rd_fifo(bs); -- /* fill in tx fifo as much as possible */ -- bcm2835_wr_fifo(bs); -- /* if we still expect some data after the read, -- * check for a possible timeout -- */ -- if (bs->rx_len && time_after(jiffies, timeout)) { -- /* Transfer complete - reset SPI HW */ -- bcm2835_spi_reset_hw(master); -- /* and return timeout */ -- return -ETIMEDOUT; -- } -- } -- -- /* Transfer complete - reset SPI HW */ -- bcm2835_spi_reset_hw(master); -- /* and return without waiting for completion */ -- return 0; --} -- - static int bcm2835_spi_transfer_one_irq(struct spi_master *master, - struct spi_device *spi, - struct spi_transfer *tfr, -@@ -229,6 +193,55 @@ static int bcm2835_spi_transfer_one_irq( - return 1; - } - -+static int bcm2835_spi_transfer_one_poll(struct spi_master *master, -+ struct spi_device *spi, -+ struct spi_transfer *tfr, -+ u32 cs, -+ unsigned long xfer_time_us) -+{ -+ struct bcm2835_spi *bs = spi_master_get_devdata(master); -+ unsigned long timeout; -+ -+ /* enable HW block without interrupts */ -+ bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_TA); -+ -+ /* fill in the fifo before timeout calculations -+ * if we are interrupted here, then the data is -+ * getting transferred by the HW while we are interrupted -+ */ -+ bcm2835_wr_fifo(bs); -+ -+ /* set the timeout */ -+ timeout = jiffies + BCM2835_SPI_POLLING_JIFFIES; -+ -+ /* loop until finished the transfer */ -+ while (bs->rx_len) { -+ /* fill in tx fifo with remaining data */ -+ bcm2835_wr_fifo(bs); -+ -+ /* read from fifo as much as possible */ -+ bcm2835_rd_fifo(bs); -+ -+ /* if there is still data pending to read -+ * then check the timeout -+ */ -+ if (bs->rx_len && time_after(jiffies, timeout)) { -+ dev_dbg_ratelimited(&spi->dev, -+ "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n", -+ jiffies - timeout, -+ bs->tx_len, bs->rx_len); -+ /* fall back to interrupt mode */ -+ return bcm2835_spi_transfer_one_irq(master, spi, -+ tfr, cs); -+ } -+ } -+ -+ /* Transfer complete - reset SPI HW */ -+ bcm2835_spi_reset_hw(master); -+ /* and return without waiting for completion */ -+ return 0; -+} -+ - static int bcm2835_spi_transfer_one(struct spi_master *master, - struct spi_device *spi, - struct spi_transfer *tfr) |