Commit be1c770028b832945680ebf5c0d49b831ba719d5
Committed by
Lee Jones
Lee Jones
1 parent
dfa52c852d
Exists in
ti-lsk-linux-4.1.y
and in
10 other branches
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>
Showing 1 changed file with 5 additions and 0 deletions Side-by-side Diff
drivers/mfd/tps65910.c
| ... | ... | @@ -486,6 +486,11 @@ |
| 486 | 486 | tps65910->i2c_client = i2c; |
| 487 | 487 | tps65910->id = chip_id; |
| 488 | 488 | |
| 489 | + /* Work around silicon erratum SWCZ010: the tps65910 may miss the | |
| 490 | + * first I2C transfer. So issue a dummy transfer before the first | |
| 491 | + * real transfer. | |
| 492 | + */ | |
| 493 | + i2c_master_send(i2c, "", 1); | |
| 489 | 494 | tps65910->regmap = devm_regmap_init_i2c(i2c, &tps65910_regmap_config); |
| 490 | 495 | if (IS_ERR(tps65910->regmap)) { |
| 491 | 496 | ret = PTR_ERR(tps65910->regmap); |