diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.9/950-0107-i2c-bcm2835-Protect-against-unexpected-TXW-RXR-inter.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.9/950-0107-i2c-bcm2835-Protect-against-unexpected-TXW-RXR-inter.patch | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.9/950-0107-i2c-bcm2835-Protect-against-unexpected-TXW-RXR-inter.patch b/target/linux/brcm2708/patches-4.9/950-0107-i2c-bcm2835-Protect-against-unexpected-TXW-RXR-inter.patch new file mode 100644 index 0000000..6646d77 --- /dev/null +++ b/target/linux/brcm2708/patches-4.9/950-0107-i2c-bcm2835-Protect-against-unexpected-TXW-RXR-inter.patch @@ -0,0 +1,124 @@ +From 8feb8081c74d15ce368baa42981ca98e77800c03 Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org> +Date: Fri, 23 Sep 2016 18:24:38 +0200 +Subject: [PATCH] i2c: bcm2835: Protect against unexpected TXW/RXR interrupts +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +If an unexpected TXW or RXR interrupt occurs (msg_buf_remaining == 0), +the driver has no way to fill/drain the FIFO to stop the interrupts. +In this case the controller has to be disabled and the transfer +completed to avoid hang. + +(CLKT | ERR) and DONE interrupts are completed in their own paths, and +the controller is disabled in the transfer function after completion. +Unite the code paths and do disabling inside the interrupt routine. + +Clear interrupt status bits in the united completion path instead of +trying to do it on every interrupt which isn't necessary. +Only CLKT, ERR and DONE can be cleared that way. + +Add the status value to the error value in case of TXW/RXR errors to +distinguish them from the other S_LEN error. + +Signed-off-by: Noralf Trønnes <noralf@tronnes.org> +Reviewed-by: Eric Anholt <eric@anholt.net> +--- + drivers/i2c/busses/i2c-bcm2835.c | 40 +++++++++++++++++++++++++++++++--------- + 1 file changed, 31 insertions(+), 9 deletions(-) + +--- a/drivers/i2c/busses/i2c-bcm2835.c ++++ b/drivers/i2c/busses/i2c-bcm2835.c +@@ -50,8 +50,6 @@ + #define BCM2835_I2C_S_CLKT BIT(9) + #define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ + +-#define BCM2835_I2C_BITMSK_S 0x03FF +- + #define BCM2835_I2C_CDIV_MIN 0x0002 + #define BCM2835_I2C_CDIV_MAX 0xFFFE + +@@ -111,20 +109,26 @@ static void bcm2835_drain_rxfifo(struct + } + } + ++/* ++ * Note about I2C_C_CLEAR on error: ++ * The I2C_C_CLEAR on errors will take some time to resolve -- if you were in ++ * non-idle state and I2C_C_READ, it sets an abort_rx flag and runs through ++ * the state machine to send a NACK and a STOP. Since we're setting CLEAR ++ * without I2CEN, that NACK will be hanging around queued up for next time ++ * we start the engine. ++ */ ++ + static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) + { + struct bcm2835_i2c_dev *i2c_dev = data; + u32 val, err; + + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); +- val &= BCM2835_I2C_BITMSK_S; +- bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); + + err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); + if (err) { + i2c_dev->msg_err = err; +- complete(&i2c_dev->completion); +- return IRQ_HANDLED; ++ goto complete; + } + + if (val & BCM2835_I2C_S_DONE) { +@@ -137,21 +141,38 @@ static irqreturn_t bcm2835_i2c_isr(int t + i2c_dev->msg_err = BCM2835_I2C_S_LEN; + else + i2c_dev->msg_err = 0; +- complete(&i2c_dev->completion); +- return IRQ_HANDLED; ++ goto complete; + } + + if (val & BCM2835_I2C_S_TXW) { ++ if (!i2c_dev->msg_buf_remaining) { ++ i2c_dev->msg_err = val | BCM2835_I2C_S_LEN; ++ goto complete; ++ } ++ + bcm2835_fill_txfifo(i2c_dev); + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_RXR) { ++ if (!i2c_dev->msg_buf_remaining) { ++ i2c_dev->msg_err = val | BCM2835_I2C_S_LEN; ++ goto complete; ++ } ++ + bcm2835_drain_rxfifo(i2c_dev); + return IRQ_HANDLED; + } + + return IRQ_NONE; ++ ++complete: ++ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); ++ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, BCM2835_I2C_S_CLKT | ++ BCM2835_I2C_S_ERR | BCM2835_I2C_S_DONE); ++ complete(&i2c_dev->completion); ++ ++ return IRQ_HANDLED; + } + + static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, +@@ -181,8 +202,9 @@ static int bcm2835_i2c_xfer_msg(struct b + + time_left = wait_for_completion_timeout(&i2c_dev->completion, + BCM2835_I2C_TIMEOUT); +- bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); + if (!time_left) { ++ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, ++ BCM2835_I2C_C_CLEAR); + dev_err(i2c_dev->dev, "i2c transfer timed out\n"); + return -ETIMEDOUT; + } |