linux-kernel - Re: [RESEND PATCH v3 2/5] charger: tps65090: Allow charger module to be used when no irq

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Date:	Tue, 29 Apr 2014 09:39:46 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Anton Vorontsov <anton@...msg.org>
Cc:	Olof Johansson <olof@...om.net>,
	Sachin Kamat <sachin.kamat@...aro.org>,
	AJAY KUMAR RAMAKRISHNA SHYMALAMMA <ajaykumar.rs@...sung.com>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"broonie@...nel.org" <broonie@...nel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Doug Anderson <dianders@...omium.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v3 2/5] charger: tps65090: Allow charger module to
 be used when no irq

Anton,

On Wed, Apr 23, 2014 at 8:56 AM, Doug Anderson <dianders@...omium.org> wrote:
> On the ARM Chromebook tps65090 has two masters: the AP (the main
> processor running linux) and the EC (the embedded controller).  The AP
> is allowed to mess with FETs but the EC is in charge of charge control.
>
> The tps65090 interupt line is routed to both the AP and the EC, which
> can cause quite a headache.  Having two people adjusting masks and
> acking interrupts is a recipe for disaster.
>
> In the shipping kernel we had a hack to have the AP pay attention to
> the IRQ but not to ack it.  It also wasn't supposed to configure the
> IRQ in any way.  That hack allowed us to detect when the device was
> charging without messing with the EC's state.
>
> The current tps65090 infrastructure makes the above difficult, and it
> was a bit of a hack to begin with.  Rather than uglify the driver to
> support it, just extend the driver's existing notion of "no irq" to
> the charger.  This makes the charger code poll every 2 seconds for AC
> detect, which is sufficient.
>
> For proper functioning, requires (mfd: tps65090: Don't tell child
> devices we have an IRQ if we don't).  If we don't have that patch
> we'll simply fail to probe on devices without an interrupt (just like
> we did before this patch).
>
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> ---
> Changes in v3: None
> Changes in v2:
> - Split noirq (polling mode) changes into MFD and charger
>
>  drivers/power/tps65090-charger.c | 76 +++++++++++++++++++++++++++++++---------
>  1 file changed, 59 insertions(+), 17 deletions(-)

All the rest of this series has been acked and applied.  Do you have
time to review this patch?

Thanks!  :)

-Doug
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