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authorArnout Vandecappelle (Essensium/Mind) <arnout@mind.be>2014-08-22 17:30:56 +0200
committerLee Jones <lee.jones@linaro.org>2014-09-26 08:15:48 +0100
commitbe1c770028b832945680ebf5c0d49b831ba719d5 (patch)
treece5b123bff0c5b6d8f1f5541045c9225ddcba697 /drivers
parentdfa52c852dd3fcf3c0e696ab2d7df0bf91b2aed9 (diff)
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')
-rw-r--r--drivers/mfd/tps65910.c5
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);