linux-kernel - Re: [PATCH 4.19 20/54] power: supply: axp288_charger: Add special handling for HP Pavilion x2 10

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Date:   Sun, 12 Apr 2020 22:46:07 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Hans de Goede <hdegoede@...hat.com>,
        Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: Re: [PATCH 4.19 20/54] power: supply: axp288_charger: Add special
 handling for HP Pavilion x2 10

On Sat 2020-04-11 14:09:02, Greg Kroah-Hartman wrote:
> From: Hans de Goede <hdegoede@...hat.com>
> 
> commit 9c80662a74cd2a5d1113f5c69d027face963a556 upstream.
> 
> Some HP Pavilion x2 10 models use an AXP288 for charging and fuel-gauge.
> We use a native power_supply / PMIC driver in this case, because on most
> models with an AXP288 the ACPI AC / Battery code is either completely
> missing or relies on custom / proprietary ACPI OpRegions which Linux
> does not implement.
> 
> The native drivers mostly work fine, but there are 2 problems:
> 
> 1. These model uses a Type-C connector for charging which the AXP288 does
> not support. As long as a Type-A charger (which uses the USB data pins for
> charger type detection) is used everything is fine. But if a Type-C
> charger is used (such as the charger shipped with the device) then the
> charger is not recognized.
> 
> So we end up slowly discharging the device even though a charger is
> connected, because we are limiting the current from the charger to 500mA.
> To make things worse this happens with the device's official charger.
> 
> Looking at the ACPI tables HP has "solved" the problem of the AXP288 not
> being able to recognize Type-C chargers by simply always programming the
> input-current-limit at 3000mA and relying on a Vhold setting of 4.7V
> (normally 4.4V) to limit the current intake if the charger cannot handle
> this.

Hmm.. Drawing 3A from port designed for .5A... is not that a bit
dangerous? It is certainly against the specs.

I believe it will work okay 90% of time, but maybe something overheats
or some fuse trips in the remaining cases. I believe I've seen fuse
triping on USB port of my home router..

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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