From 751faedf06e895a17e985a88ef5b6364ffd797ed Mon Sep 17 00:00:00 2001 From: Carl Philipp Klemm Date: Sun, 17 Jan 2021 22:48:53 +0100 Subject: power: supply: cpcap-charger: Add usleep to cpcap charger to avoid usb plug bounce Adds 80000 us sleep when the usb cable is plugged in to hopefully avoid bouncing contacts. Upon pluging in the usb cable vbus will bounce for some time, causing cpcap to dissconnect charging due to detecting an undervoltage condition. This is a scope of vbus on xt894 while quickly inserting the usb cable with firm force, probed at the far side of the usb socket and vbus loaded with approx 1k: http://uvos.xyz/maserati/usbplug.jpg. As can clearly be seen, vbus is all over the place for the first 15 ms or so with a small blip at ~40 ms this causes the cpcap to trip up and disable charging again. The delay helps cpcap_usb_detect avoid the worst of this. It is, however, still not ideal as strong vibrations can cause the issue to reapear any time during charging. I have however not been able to cause the device to stop charging due to this in practice as it is hard to vibrate the device such that the vbus pins start bouncing again but cpcap_usb_detect is not called again due to a detected disconnect/reconnect event. Signed-off-by: Carl Philipp Klemm Tested-by: Tony Lindgren Signed-off-by: Sebastian Reichel --- drivers/power/supply/cpcap-charger.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/power') diff --git a/drivers/power/supply/cpcap-charger.c b/drivers/power/supply/cpcap-charger.c index 3f06eb826ac2..2a8915c3e73e 100644 --- a/drivers/power/supply/cpcap-charger.c +++ b/drivers/power/supply/cpcap-charger.c @@ -668,6 +668,9 @@ static void cpcap_usb_detect(struct work_struct *work) return; } + /* Delay for 80ms to avoid vbus bouncing when usb cable is plugged in */ + usleep_range(80000, 120000); + /* Throttle chrgcurr2 interrupt for charger done and retry */ switch (ddata->status) { case POWER_SUPPLY_STATUS_CHARGING: -- cgit