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220 lines
6.7 KiB
Diff
220 lines
6.7 KiB
Diff
From 58ee33ad32d4a00735252718f8bac3f7592af6e7 Mon Sep 17 00:00:00 2001
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From: jeanleflambeur <catalin.vasile@gmail.com>
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Date: Sun, 1 Feb 2015 12:35:38 +0100
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Subject: [PATCH 112/114] Fix grabbing lock from atomic context in i2c driver
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2 main changes:
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- check for timeouts in the bcm2708_bsc_setup function as indicated by this comment:
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/* poll for transfer start bit (should only take 1-20 polls) */
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This implies that the setup function can now fail so account for this everywhere it's called
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- Removed the clk_get_rate call from inside the setup function as it locks a mutex and that's not ok since we call it from under a spin lock.
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removed dead code and update comment
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fixed typo in comment
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---
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drivers/i2c/busses/i2c-bcm2708.c | 90 +++++++++++++++++++++++++++++-----------
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1 file changed, 65 insertions(+), 25 deletions(-)
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--- a/drivers/i2c/busses/i2c-bcm2708.c
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+++ b/drivers/i2c/busses/i2c-bcm2708.c
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@@ -68,6 +68,7 @@
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#define BSC_S_TA 0x00000001
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#define I2C_TIMEOUT_MS 150
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+#define I2C_WAIT_LOOP_COUNT 40
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#define DRV_NAME "bcm2708_i2c"
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@@ -86,6 +87,7 @@ struct bcm2708_i2c {
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void __iomem *base;
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int irq;
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struct clk *clk;
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+ u32 cdiv;
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struct completion done;
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@@ -109,10 +111,10 @@ static void bcm2708_i2c_init_pinmode(int
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int pin;
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u32 *gpio = ioremap(GPIO_BASE, SZ_16K);
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- BUG_ON(id != 0 && id != 1);
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+ BUG_ON(id != 0 && id != 1);
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/* BSC0 is on GPIO 0 & 1, BSC1 is on GPIO 2 & 3 */
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for (pin = id*2+0; pin <= id*2+1; pin++) {
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-printk("bcm2708_i2c_init_pinmode(%d,%d)\n", id, pin);
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+ printk("bcm2708_i2c_init_pinmode(%d,%d)\n", id, pin);
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INP_GPIO(pin); /* set mode to GPIO input first */
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SET_GPIO_ALT(pin, 0); /* set mode to ALT 0 */
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}
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@@ -151,16 +153,16 @@ static inline void bcm2708_bsc_fifo_fill
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bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]);
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}
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-static inline void bcm2708_bsc_setup(struct bcm2708_i2c *bi)
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+static inline int bcm2708_bsc_setup(struct bcm2708_i2c *bi)
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{
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- unsigned long bus_hz;
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u32 cdiv, s;
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u32 c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_ST | BSC_C_CLEAR_1;
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+ int wait_loops = I2C_WAIT_LOOP_COUNT;
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- bus_hz = clk_get_rate(bi->clk);
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- cdiv = bus_hz / baudrate;
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- if (cdiv > 0xffff)
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- cdiv = 0xffff;
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+ /* Can't call clk_get_rate as it locks a mutex and here we are spinlocked.
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+ * Use the value that we cached in the probe.
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+ */
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+ cdiv = bi->cdiv;
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if (bi->msg->flags & I2C_M_RD)
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c |= BSC_C_INTR | BSC_C_READ;
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@@ -177,17 +179,25 @@ static inline void bcm2708_bsc_setup(str
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- Both messages to same slave address
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- Write message can fit inside FIFO (16 bytes or less) */
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if ( (bi->nmsgs > 1) &&
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- !(bi->msg[0].flags & I2C_M_RD) && (bi->msg[1].flags & I2C_M_RD) &&
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- (bi->msg[0].addr == bi->msg[1].addr) && (bi->msg[0].len <= 16)) {
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+ !(bi->msg[0].flags & I2C_M_RD) && (bi->msg[1].flags & I2C_M_RD) &&
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+ (bi->msg[0].addr == bi->msg[1].addr) && (bi->msg[0].len <= 16)) {
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/* Fill FIFO with entire write message (16 byte FIFO) */
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- while (bi->pos < bi->msg->len)
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+ while (bi->pos < bi->msg->len) {
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bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]);
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+ }
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/* Start write transfer (no interrupts, don't clear FIFO) */
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bcm2708_wr(bi, BSC_C, BSC_C_I2CEN | BSC_C_ST);
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+
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/* poll for transfer start bit (should only take 1-20 polls) */
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do {
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s = bcm2708_rd(bi, BSC_S);
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- } while (!(s & (BSC_S_TA | BSC_S_ERR | BSC_S_CLKT | BSC_S_DONE)));
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+ } while (!(s & (BSC_S_TA | BSC_S_ERR | BSC_S_CLKT | BSC_S_DONE)) && --wait_loops >= 0);
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+
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+ /* did we time out or some error occured? */
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+ if (wait_loops < 0 || (s & (BSC_S_ERR | BSC_S_CLKT))) {
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+ return -1;
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+ }
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+
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/* Send next read message before the write transfer finishes. */
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bi->nmsgs--;
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bi->msg++;
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@@ -197,6 +207,8 @@ static inline void bcm2708_bsc_setup(str
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}
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}
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bcm2708_wr(bi, BSC_C, c);
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+
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+ return 0;
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}
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static irqreturn_t bcm2708_i2c_interrupt(int irq, void *dev_id)
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@@ -204,13 +216,15 @@ static irqreturn_t bcm2708_i2c_interrupt
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struct bcm2708_i2c *bi = dev_id;
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bool handled = true;
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u32 s;
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+ int ret;
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spin_lock(&bi->lock);
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/* we may see camera interrupts on the "other" I2C channel
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- Just return if we've not sent anything */
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- if (!bi->nmsgs || !bi->msg )
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+ Just return if we've not sent anything */
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+ if (!bi->nmsgs || !bi->msg) {
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goto early_exit;
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+ }
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s = bcm2708_rd(bi, BSC_S);
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@@ -218,13 +232,16 @@ static irqreturn_t bcm2708_i2c_interrupt
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bcm2708_bsc_reset(bi);
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bi->error = true;
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+ bi->msg = 0; /* to inform the that all work is done */
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+ bi->nmsgs = 0;
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/* wake up our bh */
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complete(&bi->done);
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} else if (s & BSC_S_DONE) {
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bi->nmsgs--;
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- if (bi->msg->flags & I2C_M_RD)
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+ if (bi->msg->flags & I2C_M_RD) {
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bcm2708_bsc_fifo_drain(bi);
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+ }
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bcm2708_bsc_reset(bi);
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@@ -232,8 +249,19 @@ static irqreturn_t bcm2708_i2c_interrupt
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/* advance to next message */
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bi->msg++;
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bi->pos = 0;
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- bcm2708_bsc_setup(bi);
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+ ret = bcm2708_bsc_setup(bi);
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+ if (ret < 0) {
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+ bcm2708_bsc_reset(bi);
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+ bi->error = true;
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+ bi->msg = 0; /* to inform the that all work is done */
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+ bi->nmsgs = 0;
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+ /* wake up our bh */
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+ complete(&bi->done);
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+ goto early_exit;
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+ }
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} else {
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+ bi->msg = 0; /* to inform the that all work is done */
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+ bi->nmsgs = 0;
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/* wake up our bh */
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complete(&bi->done);
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}
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@@ -266,22 +294,33 @@ static int bcm2708_i2c_master_xfer(struc
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bi->nmsgs = num;
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bi->error = false;
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- bcm2708_bsc_setup(bi);
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+ ret = bcm2708_bsc_setup(bi);
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- /* unlockig _after_ the setup to avoid races with the interrupt routine */
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spin_unlock_irqrestore(&bi->lock, flags);
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- ret = wait_for_completion_timeout(&bi->done,
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- msecs_to_jiffies(I2C_TIMEOUT_MS));
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+ /* check the result of the setup */
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+ if (ret < 0)
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+ {
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+ dev_err(&adap->dev, "transfer setup timed out\n");
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+ goto error_timeout;
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+ }
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+
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+ ret = wait_for_completion_timeout(&bi->done, msecs_to_jiffies(I2C_TIMEOUT_MS));
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if (ret == 0) {
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dev_err(&adap->dev, "transfer timed out\n");
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- spin_lock_irqsave(&bi->lock, flags);
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- bcm2708_bsc_reset(bi);
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- spin_unlock_irqrestore(&bi->lock, flags);
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- return -ETIMEDOUT;
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+ goto error_timeout;
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}
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- return bi->error ? -EIO : num;
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+ ret = bi->error ? -EIO : num;
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+ return ret;
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+
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+error_timeout:
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+ spin_lock_irqsave(&bi->lock, flags);
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+ bcm2708_bsc_reset(bi);
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+ bi->msg = 0; /* to inform the interrupt handler that there's nothing else to be done */
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+ bi->nmsgs = 0;
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+ spin_unlock_irqrestore(&bi->lock, flags);
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+ return -ETIMEDOUT;
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}
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static u32 bcm2708_i2c_functionality(struct i2c_adapter *adap)
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@@ -406,6 +445,7 @@ static int bcm2708_i2c_probe(struct plat
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cdiv = 0xffff;
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baudrate = bus_hz / cdiv;
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}
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+ bi->cdiv = cdiv;
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dev_info(&pdev->dev, "BSC%d Controller at 0x%08lx (irq %d) (baudrate %d)\n",
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pdev->id, (unsigned long)regs->start, irq, baudrate);
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