openwrtv4/target/linux/brcm2708/patches-4.9/950-0107-i2c-bcm2835-Protect-against-unexpected-TXW-RXR-inter.patch
Rafał Miłecki fce21ae4cc brcm2708: rename all patches from raspberrypi git tree to use 950 prefix
Right now all brcm2708 patches are extracted from the non-mainline
raspberrypi/linux git tree. Many of them are hacks and/or are unneeded
in LEDE. Raspberry Pi is getting better and better mainline support so
it would be nice to finally start maintaining patches in a cleaner way:
1) Backport patches accepted in upstream tree
2) Start using upstream drivers
3) Pick only these patches that are needed for more complete support

Handling above tasks requires grouping patches - ideally using the same
prefixes as generic ones. It means we should rename existing patches to
use some high prefix. This will allow e.g. use 0xx for backported code.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Stijn Tintel <stijn@linux-ipv6.be>
2017-03-24 08:06:35 +01:00

124 lines
3.8 KiB
Diff

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
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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;
}