Messages in this thread |  | | From | Chen-Yu Tsai <> | Date | Mon, 6 Jan 2020 12:27:01 +0800 | Subject | Re: [linux-sunxi] [PATCH v2 9/9] power: supply: axp20x_usb_power: Only poll while offline |
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On Sun, Jan 5, 2020 at 9:24 AM Samuel Holland <samuel@sholland.org> wrote: > > Investigation on the AXP803 shows that VBUS_PLUGIN/VBUS_REMOVAL IRQs are > triggered on the rising/falling edge of AXP20X_PWR_STATUS_VBUS_USED. The > reason IRQs do not arrive while N_VBUSEN/DRIVEVBUS is high is because > AXP20X_PWR_STATUS_VBUS_USED also never goes high. > > This also means that if VBUS is online, a VBUS_REMOVAL IRQ is received > immediately on setting N_VBUSEN/DRIVEVBUS high (and VBUS_PLUGIN shortly > after it is set back low). This was also verified to be the case when > manually offlining VBUS through AXP20X_VBUS_PATH_SELECT. > > As long as VBUS is online, a present->absent transition necessarily > implies an online->offline transition. Since will cause an IRQ, there is > no need to poll while VBUS is online. > > To ensure the driver's view of VBUS online status remains accurate, > unconditionally poll once when receiving an IRQ and when resuming. If > VBUS is still online at that time, polling will cease until the next > VBUS_REMOVAL IRQ. > > Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
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