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190 lines
6.2 KiB
190 lines
6.2 KiB
8 years ago
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From 98629f09f3ceb7f2a559b48b4a70028485583f5e Mon Sep 17 00:00:00 2001
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8 years ago
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From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
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Date: Tue, 1 Nov 2016 15:15:41 +0100
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Subject: [PATCH] i2c: bcm2835: Add debug support
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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This adds a debug module parameter to aid in debugging transfer issues
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by printing info to the kernel log. When enabled, status values are
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collected in the interrupt routine and msg info in
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bcm2835_i2c_start_transfer(). This is done in a way that tries to avoid
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affecting timing. Having printk in the isr can mask issues.
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debug values (additive):
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1: Print info on error
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2: Print info on all transfers
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3: Print messages before transfer is started
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The value can be changed at runtime:
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/sys/module/i2c_bcm2835/parameters/debug
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Example output, debug=3:
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[ 747.114448] bcm2835_i2c_xfer: msg(1/2) write addr=0x54, len=2 flags= [i2c1]
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[ 747.114463] bcm2835_i2c_xfer: msg(2/2) read addr=0x54, len=32 flags= [i2c1]
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[ 747.117809] start_transfer: msg(1/2) write addr=0x54, len=2 flags= [i2c1]
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[ 747.117825] isr: remain=2, status=0x30000055 : TA TXW TXD TXE [i2c1]
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[ 747.117839] start_transfer: msg(2/2) read addr=0x54, len=32 flags= [i2c1]
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[ 747.117849] isr: remain=32, status=0xd0000039 : TA RXR TXD RXD [i2c1]
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[ 747.117861] isr: remain=20, status=0xd0000039 : TA RXR TXD RXD [i2c1]
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[ 747.117870] isr: remain=8, status=0x32 : DONE TXD RXD [i2c1]
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Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
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---
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drivers/i2c/busses/i2c-bcm2835.c | 99 +++++++++++++++++++++++++++++++++++++++-
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1 file changed, 98 insertions(+), 1 deletion(-)
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--- a/drivers/i2c/busses/i2c-bcm2835.c
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+++ b/drivers/i2c/busses/i2c-bcm2835.c
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@@ -53,6 +53,18 @@
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#define BCM2835_I2C_CDIV_MIN 0x0002
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#define BCM2835_I2C_CDIV_MAX 0xFFFE
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+static unsigned int debug;
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+module_param(debug, uint, 0644);
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+MODULE_PARM_DESC(debug, "1=err, 2=isr, 3=xfer");
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+
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+#define BCM2835_DEBUG_MAX 512
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+struct bcm2835_debug {
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+ struct i2c_msg *msg;
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+ int msg_idx;
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+ size_t remain;
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+ u32 status;
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+};
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+
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struct bcm2835_i2c_dev {
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struct device *dev;
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void __iomem *regs;
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@@ -66,8 +78,78 @@ struct bcm2835_i2c_dev {
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u32 msg_err;
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u8 *msg_buf;
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size_t msg_buf_remaining;
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+ struct bcm2835_debug debug[BCM2835_DEBUG_MAX];
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+ unsigned int debug_num;
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+ unsigned int debug_num_msgs;
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};
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+static inline void bcm2835_debug_add(struct bcm2835_i2c_dev *i2c_dev, u32 s)
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+{
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+ if (!i2c_dev->debug_num_msgs || i2c_dev->debug_num >= BCM2835_DEBUG_MAX)
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+ return;
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+
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+ i2c_dev->debug[i2c_dev->debug_num].msg = i2c_dev->curr_msg;
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+ i2c_dev->debug[i2c_dev->debug_num].msg_idx =
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+ i2c_dev->debug_num_msgs - i2c_dev->num_msgs;
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+ i2c_dev->debug[i2c_dev->debug_num].remain = i2c_dev->msg_buf_remaining;
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+ i2c_dev->debug[i2c_dev->debug_num].status = s;
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+ i2c_dev->debug_num++;
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+}
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+
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+static void bcm2835_debug_print_status(struct bcm2835_i2c_dev *i2c_dev,
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+ struct bcm2835_debug *d)
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+{
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+ u32 s = d->status;
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+
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+ pr_info("isr: remain=%zu, status=0x%x : %s%s%s%s%s%s%s%s%s%s [i2c%d]\n",
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+ d->remain, s,
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+ s & BCM2835_I2C_S_TA ? "TA " : "",
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+ s & BCM2835_I2C_S_DONE ? "DONE " : "",
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+ s & BCM2835_I2C_S_TXW ? "TXW " : "",
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+ s & BCM2835_I2C_S_RXR ? "RXR " : "",
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+ s & BCM2835_I2C_S_TXD ? "TXD " : "",
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+ s & BCM2835_I2C_S_RXD ? "RXD " : "",
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+ s & BCM2835_I2C_S_TXE ? "TXE " : "",
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+ s & BCM2835_I2C_S_RXF ? "RXF " : "",
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+ s & BCM2835_I2C_S_ERR ? "ERR " : "",
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+ s & BCM2835_I2C_S_CLKT ? "CLKT " : "",
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+ i2c_dev->adapter.nr);
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+}
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+
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+static void bcm2835_debug_print_msg(struct bcm2835_i2c_dev *i2c_dev,
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+ struct i2c_msg *msg, int i, int total,
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+ const char *fname)
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+{
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+ pr_info("%s: msg(%d/%d) %s addr=0x%02x, len=%u flags=%s%s%s%s%s%s%s [i2c%d]\n",
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+ fname, i, total,
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+ msg->flags & I2C_M_RD ? "read" : "write", msg->addr, msg->len,
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+ msg->flags & I2C_M_TEN ? "TEN" : "",
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+ msg->flags & I2C_M_RECV_LEN ? "RECV_LEN" : "",
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+ msg->flags & I2C_M_NO_RD_ACK ? "NO_RD_ACK" : "",
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+ msg->flags & I2C_M_IGNORE_NAK ? "IGNORE_NAK" : "",
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+ msg->flags & I2C_M_REV_DIR_ADDR ? "REV_DIR_ADDR" : "",
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+ msg->flags & I2C_M_NOSTART ? "NOSTART" : "",
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+ msg->flags & I2C_M_STOP ? "STOP" : "",
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+ i2c_dev->adapter.nr);
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+}
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+
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+static void bcm2835_debug_print(struct bcm2835_i2c_dev *i2c_dev)
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+{
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+ struct bcm2835_debug *d;
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+ unsigned int i;
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+
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+ for (i = 0; i < i2c_dev->debug_num; i++) {
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+ d = &i2c_dev->debug[i];
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+ if (d->status == ~0)
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+ bcm2835_debug_print_msg(i2c_dev, d->msg, d->msg_idx,
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+ i2c_dev->debug_num_msgs, "start_transfer");
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+ else
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+ bcm2835_debug_print_status(i2c_dev, d);
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+ }
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+ if (i2c_dev->debug_num >= BCM2835_DEBUG_MAX)
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+ pr_info("BCM2835_DEBUG_MAX reached\n");
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+}
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+
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static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
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u32 reg, u32 val)
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{
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@@ -170,6 +252,7 @@ static void bcm2835_i2c_start_transfer(s
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bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
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bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
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bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
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+ bcm2835_debug_add(i2c_dev, ~0);
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}
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/*
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@@ -187,6 +270,7 @@ static irqreturn_t bcm2835_i2c_isr(int t
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u32 val, err;
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val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
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+ bcm2835_debug_add(i2c_dev, val);
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err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
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if (err) {
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@@ -251,6 +335,13 @@ static int bcm2835_i2c_xfer(struct i2c_a
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unsigned long time_left;
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int i, ret;
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+ if (debug)
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+ i2c_dev->debug_num_msgs = num;
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+
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+ if (debug > 2)
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+ for (i = 0; i < num; i++)
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+ bcm2835_debug_print_msg(i2c_dev, &msgs[i], i + 1, num, __func__);
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+
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for (i = 0; i < (num - 1); i++)
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if (msgs[i].flags & I2C_M_RD) {
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dev_warn_once(i2c_dev->dev,
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@@ -270,6 +361,10 @@ static int bcm2835_i2c_xfer(struct i2c_a
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time_left = wait_for_completion_timeout(&i2c_dev->completion,
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adap->timeout);
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+ if (debug > 1 || (debug && (!time_left || i2c_dev->msg_err)))
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+ bcm2835_debug_print(i2c_dev);
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+ i2c_dev->debug_num_msgs = 0;
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+ i2c_dev->debug_num = 0;
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if (!time_left) {
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bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C,
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BCM2835_I2C_C_CLEAR);
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@@ -280,7 +375,9 @@ static int bcm2835_i2c_xfer(struct i2c_a
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if (!i2c_dev->msg_err)
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return num;
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- dev_dbg(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
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+ if (debug)
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+ dev_err(i2c_dev->dev, "i2c transfer failed: %x\n",
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+ i2c_dev->msg_err);
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if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
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return -EREMOTEIO;
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