From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: [PATCH v6] power: supply: bq24190_charger: Add disable-reset device-property Date: Fri, 14 Apr 2017 18:52:33 +0200 Message-ID: <20170414165233.4532-1-hdegoede@redhat.com> Return-path: Received: from mx1.redhat.com ([209.132.183.28]:36426 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271AbdDNQwh (ORCPT ); Fri, 14 Apr 2017 12:52:37 -0400 Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Sebastian Reichel Cc: Hans de Goede , Liam Breck , Tony Lindgren , linux-pm@vger.kernel.org, Liam Breck Allow platform-code to disable the reset on probe and suspend/resume by setting a "disable-reset" boolean device property on the device. There are several reasons why the platform-code may want to disable the reset on probe and suspend/resume: 1) Resetting the charger should never be necessary it should always have sane values programmed. If it is running with invalid values while we are not running (system turned off or suspended) there is a big problem as that may lead to overcharging the battery. 2) The reset in suspend() is meant to put the charger back into default mode, but this is not necessary and not a good idea. If the charger has been programmed with a higher max charge_current / charge_voltage then putting it back in default-mode will reset those to the safe power-on defaults, leading to slower charging, or charging to a lower voltage (and thus not using the full capacity) while suspended which is undesirable. Reprogramming the max charge_current / charge_voltage after the reset will not help here as that will put the charger back in host mode and start the i2c watchdog if the host then does not do anything for 40s (iow if we're suspended for more then 40s) the watchdog expires resetting the device to default-mode, including resetting all the registers to there safe power-on defaults. So the only way to keep using custom charge settings while suspending is to keep the charger in its normal running state with the i2c watchdog disabled. This is fine as the charger will still automatically switch from constant current to constant voltage and stop charging when the battery is full. 3) Besides never being necessary resetting the charger also causes problems on systems where the charge voltage limit is set higher then the reset value, if this is the case and the charger is reset while charging and the battery voltage is between the 2 voltages, then about half the time the charger gets confused and claims to be charging (REG08 contains 0x64) but in reality the charger has decoupled itself from VBUS (Q1 off) and is drawing 0A from VBUS, leaving the system running from the battery. This last problem is happening on a GPD-win mini PC with a bq24292i charger chip combined with a max17047 fuel-gauge and a LiHV battery. I've checked and TI does not list any errata for the bq24292i which could explain this (there are no errata at all). Cc: Liam Breck Cc: Tony Lindgren Signed-off-by: Hans de Goede --- Changes in v2: -This is a new patch in v2 of this patch-set Changes in v3: -Disable the reset code by default, but leave it around guarded by a check for a reset-on-probe device-property Changes in v4: -Rebase on top of current power-supply/next Changes in v5: -Updated commit msg to describe the hw on which I'm seeing the charger getting stuck while reset during charging and Vbat is above the reset charge volt limit Changes in v6: -Keep the reset enabled by default, allow disabling it by setting a "disable-reset" boolean device property on the device --- drivers/power/supply/bq24190_charger.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/power/supply/bq24190_charger.c b/drivers/power/supply/bq24190_charger.c index bd9e5c3..2d379a2 100644 --- a/drivers/power/supply/bq24190_charger.c +++ b/drivers/power/supply/bq24190_charger.c @@ -533,6 +533,9 @@ static int bq24190_register_reset(struct bq24190_dev_info *bdi) int ret, limit = 100; u8 v; + if (device_property_read_bool(bdi->dev, "disable-reset")) + return 0; + /* Reset the registers */ ret = bq24190_write_mask(bdi, BQ24190_REG_POC, BQ24190_REG_POC_RESET_MASK, -- 2.9.3