linux-kernel - Re: [PATCH] mfd: add bq2415x charger driver

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Message-ID: <20111206021749.GA7202@earth.universe>
Date:	Tue, 6 Dec 2011 03:17:49 +0100
From:	Sebastian Reichel <sre@...ian.org>
To:	Felipe Contreras <felipe.contreras@...ia.com>
Cc:	linux-main <linux-kernel@...r.kernel.org>,
	linux-omap <linux-omap@...r.kernel.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Pali Rohár <pali.rohar@...il.com>,
	Aliaksei Katovich <aliaksei.katovich@...ia.com>,
	Vladimir Zapolskiy <vz@...ia.com>,
	Felipe Contreras <felipe.contreras@...il.com>
Subject: Re: [PATCH] mfd: add bq2415x charger driver

Hi,

Good to hear somebody is working on this :) I planned to do this
myself, but didn't find any time for it. Here are some comments
from me:

[...]

> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig

I would expect the driver in drivers/power. But maybe MFD is
better, since the chip can also be used to power USB host?

[...]

> +#define BQ2415X_VOLTAGE_SCALE 20000

If I remember correctly (I read the specs some time ago), this can
be configured via external resistor. So this is board specific?

[...]

> +	bq2415x_i2c_write(cli, BQ2415X_CHG_CTL, 0x42);
> +	bq2415x_set_voltage(cli, 0, 4200000);
> +	bq2415x_set_current_limit(cli, 1800000, 1800000);

So it always charges with 1.8A? Shouldn't this be dependent on the
input source (e.g. 500mA from USB)? Also what's if no charger is
connected at all?

Apart from this I think those values should be exposed to sysfs
via /sys/class/power_supply.

-- Sebastian

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