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| author | Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> | 2014-08-22 17:30:56 +0200 |
|---|---|---|
| committer | Lee Jones <lee.jones@linaro.org> | 2014-09-26 08:15:48 +0100 |
| commit | be1c770028b832945680ebf5c0d49b831ba719d5 (patch) | |
| tree | ce5b123bff0c5b6d8f1f5541045c9225ddcba697 /drivers/mfd | |
| parent | dfa52c852dd3fcf3c0e696ab2d7df0bf91b2aed9 (diff) | |
| download | linux-rt-be1c770028b832945680ebf5c0d49b831ba719d5.tar.gz | |
mfd: tps65910: Work around silicon erratum SWCZ010
http://www.ti.com/lit/pdf/SWCZ010:
Glitch on SDA-SCL not managed correctly by the I2C IP
Impact:
The standard specifies that the I2C transfer should restart on a start
event in all cases. The current design does not support two consecutive
Start conditions. This can cause the first real access after such a
glitch to be corrupted.
Description:
An unexpected glitch on SDA and SCL can generate a wrong start event.
In the current design, the SCL line must toggle two times to detect a
new start event and completely restart the I2C access; hence the real
start event is not detected in the case of a single SCL toggle.
Workaround:
Repeat I2C access.
A simpler workaround is to make a dummy transfer just before the first
access to the tps65910 chip. This can be done unconditionally.
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'drivers/mfd')
| -rw-r--r-- | drivers/mfd/tps65910.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/mfd/tps65910.c b/drivers/mfd/tps65910.c index f243e75d28f3..7612d89850dd 100644 --- a/drivers/mfd/tps65910.c +++ b/drivers/mfd/tps65910.c @@ -486,6 +486,11 @@ static int tps65910_i2c_probe(struct i2c_client *i2c, tps65910->i2c_client = i2c; tps65910->id = chip_id; + /* Work around silicon erratum SWCZ010: the tps65910 may miss the + * first I2C transfer. So issue a dummy transfer before the first + * real transfer. + */ + i2c_master_send(i2c, "", 1); tps65910->regmap = devm_regmap_init_i2c(i2c, &tps65910_regmap_config); if (IS_ERR(tps65910->regmap)) { ret = PTR_ERR(tps65910->regmap); |