From 2a2c8ee2d72c4f1ba0f7fbb02dc74f971df0f934 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Sat, 16 Jun 2018 22:37:56 +0900 Subject: Revert "i2c: algo-bit: init the bus to a known state" This reverts commit 3e5f06bed72fe72166a6778f630241a893f67799. As per bugzilla #200045, this caused a regression. I don't really see a way to fix it without having the hardware. So, revert the patch and I will fix the issue I was seeing originally in the i2c-gpio driver itself. I couldn't find new users of this algorithm since, so there should be no one depending on the new behaviour. Reported-by: Sergey Larin Fixes: 3e5f06bed72f ("i2c: algo-bit: init the bus to a known state") Signed-off-by: Wolfram Sang Acked-by: Alex Deucher Tested-by: Sergey Larin Signed-off-by: Wolfram Sang Cc: stable@kernel.org --- drivers/i2c/algos/i2c-algo-bit.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'drivers/i2c/algos/i2c-algo-bit.c') diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index 4a34f311e1ff..0c0eb16d710f 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -647,11 +647,6 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, if (bit_adap->getscl == NULL) adap->quirks = &i2c_bit_quirk_no_clk_stretch; - /* Bring bus to a known state. Looks like STOP if bus is not free yet */ - setscl(bit_adap, 1); - udelay(bit_adap->udelay); - setsda(bit_adap, 1); - ret = add_adapter(adap); if (ret < 0) return ret; -- cgit v1.2.3 From 2173ed0adc7f0473e6b6ad636d8684a0d82da5e9 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Sat, 16 Jun 2018 22:37:57 +0900 Subject: i2c: algos: bit: mention our experience about initial states So, if somebody wants to re-implement this in the future, we pinpoint to a problem case. Signed-off-by: Wolfram Sang Acked-by: Alex Deucher Signed-off-by: Wolfram Sang --- drivers/i2c/algos/i2c-algo-bit.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/i2c/algos/i2c-algo-bit.c') diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index 0c0eb16d710f..6ec65adaba49 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -647,6 +647,11 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, if (bit_adap->getscl == NULL) adap->quirks = &i2c_bit_quirk_no_clk_stretch; + /* + * We tried forcing SCL/SDA to an initial state here. But that caused a + * regression, sadly. Check Bugzilla #200045 for details. + */ + ret = add_adapter(adap); if (ret < 0) return ret; -- cgit v1.2.3 From 1204d12a494cf5dff497859a5febf2ae30a28970 Mon Sep 17 00:00:00 2001 From: Jan Kundrát Date: Tue, 28 Aug 2018 10:07:40 +0200 Subject: i2c: algos: bit: make the error messages grepable MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Yep, I went looking for one of these, and I wasn't able to find it easily. That's worse than a line which is 82-chars long, IMHO. Signed-off-by: Jan Kundrát Signed-off-by: Wolfram Sang --- drivers/i2c/algos/i2c-algo-bit.c | 55 ++++++++++++++++++++++------------------ 1 file changed, 31 insertions(+), 24 deletions(-) (limited to 'drivers/i2c/algos/i2c-algo-bit.c') diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index 6ec65adaba49..c33dcfb87993 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -110,8 +110,8 @@ static int sclhi(struct i2c_algo_bit_data *adap) } #ifdef DEBUG if (jiffies != start && i2c_debug >= 3) - pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go " - "high\n", jiffies - start); + pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go high\n", + jiffies - start); #endif done: @@ -171,8 +171,9 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c) setsda(adap, sb); udelay((adap->udelay + 1) / 2); if (sclhi(adap) < 0) { /* timed out */ - bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, " - "timeout at bit #%d\n", (int)c, i); + bit_dbg(1, &i2c_adap->dev, + "i2c_outb: 0x%02x, timeout at bit #%d\n", + (int)c, i); return -ETIMEDOUT; } /* FIXME do arbitration here: @@ -185,8 +186,8 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c) } sdahi(adap); if (sclhi(adap) < 0) { /* timeout */ - bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, " - "timeout at ack\n", (int)c); + bit_dbg(1, &i2c_adap->dev, + "i2c_outb: 0x%02x, timeout at ack\n", (int)c); return -ETIMEDOUT; } @@ -215,8 +216,9 @@ static int i2c_inb(struct i2c_adapter *i2c_adap) sdahi(adap); for (i = 0; i < 8; i++) { if (sclhi(adap) < 0) { /* timeout */ - bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit " - "#%d\n", 7 - i); + bit_dbg(1, &i2c_adap->dev, + "i2c_inb: timeout at bit #%d\n", + 7 - i); return -ETIMEDOUT; } indata *= 2; @@ -265,8 +267,9 @@ static int test_bus(struct i2c_adapter *i2c_adap) goto bailout; } if (!scl) { - printk(KERN_WARNING "%s: SCL unexpected low " - "while pulling SDA low!\n", name); + printk(KERN_WARNING + "%s: SCL unexpected low while pulling SDA low!\n", + name); goto bailout; } @@ -278,8 +281,9 @@ static int test_bus(struct i2c_adapter *i2c_adap) goto bailout; } if (!scl) { - printk(KERN_WARNING "%s: SCL unexpected low " - "while pulling SDA high!\n", name); + printk(KERN_WARNING + "%s: SCL unexpected low while pulling SDA high!\n", + name); goto bailout; } @@ -291,8 +295,9 @@ static int test_bus(struct i2c_adapter *i2c_adap) goto bailout; } if (!sda) { - printk(KERN_WARNING "%s: SDA unexpected low " - "while pulling SCL low!\n", name); + printk(KERN_WARNING + "%s: SDA unexpected low while pulling SCL low!\n", + name); goto bailout; } @@ -304,8 +309,9 @@ static int test_bus(struct i2c_adapter *i2c_adap) goto bailout; } if (!sda) { - printk(KERN_WARNING "%s: SDA unexpected low " - "while pulling SCL high!\n", name); + printk(KERN_WARNING + "%s: SDA unexpected low while pulling SCL high!\n", + name); goto bailout; } @@ -352,8 +358,8 @@ static int try_address(struct i2c_adapter *i2c_adap, i2c_start(adap); } if (i && ret) - bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at " - "0x%02x: %s\n", i + 1, + bit_dbg(1, &i2c_adap->dev, + "Used %d tries to %s client at 0x%02x: %s\n", i + 1, addr & 1 ? "read from" : "write to", addr >> 1, ret == 1 ? "success" : "failed, timeout?"); return ret; @@ -442,8 +448,9 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) { if (!(flags & I2C_M_NO_RD_ACK)) acknak(i2c_adap, 0); - dev_err(&i2c_adap->dev, "readbytes: invalid " - "block length (%d)\n", inval); + dev_err(&i2c_adap->dev, + "readbytes: invalid block length (%d)\n", + inval); return -EPROTO; } /* The original count value accounts for the extra @@ -506,8 +513,8 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) return -ENXIO; } if (flags & I2C_M_RD) { - bit_dbg(3, &i2c_adap->dev, "emitting repeated " - "start condition\n"); + bit_dbg(3, &i2c_adap->dev, + "emitting repeated start condition\n"); i2c_repstart(adap); /* okay, now switch into reading mode */ addr |= 0x01; @@ -564,8 +571,8 @@ static int bit_xfer(struct i2c_adapter *i2c_adap, } ret = bit_doAddress(i2c_adap, pmsg); if ((ret != 0) && !nak_ok) { - bit_dbg(1, &i2c_adap->dev, "NAK from " - "device addr 0x%02x msg #%d\n", + bit_dbg(1, &i2c_adap->dev, + "NAK from device addr 0x%02x msg #%d\n", msgs[i].addr, i); goto bailout; } -- cgit v1.2.3