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| author | Alec Berg <alecaberg@chromium.org> | 2015-06-12 15:09:22 -0700 |
|---|---|---|
| committer | ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> | 2015-06-13 02:53:18 +0000 |
| commit | 31171730a82ff379389f46147e8194e92a6f5369 (patch) | |
| tree | bf4a7c7e025f8799f4e0ca293a9551c813876b3e | |
| parent | 1599e7a6f1734b457e8f35c287c90182189a7461 (diff) | |
| download | chrome-ec-31171730a82ff379389f46147e8194e92a6f5369.tar.gz | |
tcpc: Avoid missampling CC line immediately after transmit
Change TCPC to not sample CC ADC channels immediately after transmit
because we are likely to get a response immediately after transmit
and this could cause us to sample while traffic is on the line and
cause us to record the wrong voltage.
BUG=none
BRANCH=smaug
TEST=test on glados. put a print when TCPM is notified of CC voltage
change. without this CL, we occasionally get a false CC voltage
change. with this change, CC status stays consistent.
Change-Id: I9199a0ed98632b1f26b2b5b98f34928e4de328bf
Signed-off-by: Alec Berg <alecaberg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/277296
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
| -rw-r--r-- | common/usb_pd_tcpc.c | 35 |
1 files changed, 19 insertions, 16 deletions
diff --git a/common/usb_pd_tcpc.c b/common/usb_pd_tcpc.c index fa740ba4c4..09eeddae25 100644 --- a/common/usb_pd_tcpc.c +++ b/common/usb_pd_tcpc.c @@ -757,22 +757,25 @@ int tcpc_run(int port, int evt) else alert(port, TCPC_REG_ALERT1, TCPC_REG_ALERT1_TX_DISCARDED); - } - - /* CC pull changed, wait 1ms for CC voltage to stabilize */ - if (evt & PD_EVENT_CC) - usleep(MSEC); - - /* check CC lines */ - for (i = 0; i < 2; i++) { - /* read CC voltage */ - cc = pd_adc_read(port, i); - - /* convert voltage to status, and check status change */ - cc = cc_voltage_to_status(port, cc); - if (pd[port].cc_status[i] != cc) { - pd[port].cc_status[i] = cc; - alert(port, TCPC_REG_ALERT1, TCPC_REG_ALERT1_CC_STATUS); + } else { + /* If we have nothing to transmit, then sample CC lines */ + + /* CC pull changed, wait 1ms for CC voltage to stabilize */ + if (evt & PD_EVENT_CC) + usleep(MSEC); + + /* check CC lines */ + for (i = 0; i < 2; i++) { + /* read CC voltage */ + cc = pd_adc_read(port, i); + + /* convert voltage to status, and check status change */ + cc = cc_voltage_to_status(port, cc); + if (pd[port].cc_status[i] != cc) { + pd[port].cc_status[i] = cc; + alert(port, TCPC_REG_ALERT1, + TCPC_REG_ALERT1_CC_STATUS); + } } } |