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i2c: bcm2835: add I2C_AQ_NO_CLK_STRETCH

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As reported in the links given below. the BCM2835 has a hardware bug in
its i2c module which prevents a correct clock stretching. This patch
adds the I2C_AQ_NO_CLK_STRETCH quirk flag to i2c-bcm2835.

Signed-off-by: Nicola Corna <nicola@corna.info>
[wsa: put the links into the code as comments]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Nicola Corna 2015-10-29 12:34:25 +01:00 committed by Wolfram Sang
parent a94d306b71
commit 4dbfb5f440
1 changed files with 10 additions and 0 deletions
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10
drivers/i2c/busses/i2c-bcm2835.c
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@ -222,6 +222,15 @@ static const struct i2c_algorithm bcm2835_i2c_algo = {
.functionality = bcm2835_i2c_func,
};
/*
* This HW was reported to have problems with clock stretching:
* http://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
* https://www.raspberrypi.org/forums/viewtopic.php?p=146272
*/
static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
.flags = I2C_AQ_NO_CLK_STRETCH,
};
static int bcm2835_i2c_probe(struct platform_device *pdev)
{
struct bcm2835_i2c_dev *i2c_dev;
@ -293,6 +302,7 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
adap->algo = &bcm2835_i2c_algo;
adap->dev.parent = &pdev->dev;
adap->dev.of_node = pdev->dev.of_node;
adap->quirks = &bcm2835_i2c_quirks;
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);