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| author | Caveh Jalali <caveh@chromium.org> | 2021-07-20 22:43:34 -0700 |
|---|---|---|
| committer | Commit Bot <commit-bot@chromium.org> | 2021-07-22 04:11:06 +0000 |
| commit | 1cac4e5adeb5e64dc1e2856561e1dfdc06e7776e (patch) | |
| tree | a0e6a6197fa35685d74858d17753dcee26232dfc | |
| parent | 3e1f91586faa6dd94dca5d3a1fc72ec117c9296b (diff) | |
| download | chrome-ec-1cac4e5adeb5e64dc1e2856561e1dfdc06e7776e.tar.gz | |
ppc/nx20p348x: Disable VBUS discharge in sink mode
This explicitly disables VBUS discharge when entering sink
mode. According to the vendor, keeping VBUS discharge enabled can cause
some noise and that explains some of the instability we had observed
when charging from another chromebook and 5V3A charger.
BRANCH=none
BUG=b:193211352
TEST=charging from another chromebook is reliable now
Signed-off-by: Caveh Jalali <caveh@chromium.org>
Change-Id: I117dd3f7f9efddce00f903c2b290fa85c6052c5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3044411
Reviewed-by: Denis Brockus <dbrockus@chromium.org>
Commit-Queue: Denis Brockus <dbrockus@chromium.org>
| -rw-r--r-- | driver/ppc/nx20p348x.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/driver/ppc/nx20p348x.c b/driver/ppc/nx20p348x.c index 0de40c153b..bb6236c143 100644 --- a/driver/ppc/nx20p348x.c +++ b/driver/ppc/nx20p348x.c @@ -110,6 +110,7 @@ static int nx20p348x_set_vbus_source_current_limit(int port, static int nx20p348x_discharge_vbus(int port, int enable) { int regval; + int newval; int status; status = read_reg(port, NX20P348X_DEVICE_CONTROL_REG, ®val); @@ -117,13 +118,16 @@ static int nx20p348x_discharge_vbus(int port, int enable) return status; if (enable) - regval |= NX20P348X_CTRL_VBUSDIS_EN; + newval = regval | NX20P348X_CTRL_VBUSDIS_EN; else - regval &= ~NX20P348X_CTRL_VBUSDIS_EN; + newval = regval & ~NX20P348X_CTRL_VBUSDIS_EN; - status = write_reg(port, NX20P348X_DEVICE_CONTROL_REG, regval); + if (newval == regval) + return EC_SUCCESS; + + status = write_reg(port, NX20P348X_DEVICE_CONTROL_REG, newval); if (status) { - CPRINTS("Failed to %s vbus discharge", + CPRINTS("Failed to %s VBUS discharge", enable ? "enable" : "disable"); return status; } @@ -137,6 +141,15 @@ __maybe_unused static int nx20p3481_vbus_sink_enable(int port, int enable) int rv; int control = enable ? NX20P3481_SWITCH_CONTROL_HVSNK : 0; + if (enable) { + /* + * VBUS Discharge must be off in sink mode. + */ + rv = nx20p348x_discharge_vbus(port, 0); + if (rv) + return rv; + } + rv = write_reg(port, NX20P348X_SWITCH_CONTROL_REG, control); if (rv) return rv; @@ -202,6 +215,15 @@ __maybe_unused static int nx20p3483_vbus_sink_enable(int port, int enable) enable = !!enable; + if (enable) { + /* + * VBUS Discharge must be off in sink mode. + */ + rv = nx20p348x_discharge_vbus(port, 0); + if (rv) + return rv; + } + /* * We cannot use an EC GPIO for EN_SNK since an EC reset * will float the GPIO thus browning out the board (without |