linux-kernel - Re: [PATCH v2 0/3] input: rmi4: Regulator supply support

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Date:	Tue, 10 May 2016 08:49:04 -0700
From:	Bjorn Andersson <bjorn.andersson@...aro.org>
To:	Andrew Duggan <aduggan@...aptics.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Christopher Heiny <cheiny@...aptics.com>,
	linux-input@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: Re: [PATCH v2 0/3] input: rmi4: Regulator supply support

On Mon 09 May 17:36 PDT 2016, Andrew Duggan wrote:

> Hi Bjorn,
> 
> On 05/06/2016 09:40 PM, Bjorn Andersson wrote:
> >The first version of the regulator support patch suffered from being
> >implemented in the transport driver, as a work around for resource availability
> >racing (EPROBE_DEFER of the core driver) with the interrupt handler.
> >
> >After reconsidering the solutions discussed following that I concluded that the
> >interrupt management is not really part of the transport, neither conceptually
> >or electrically. I therefor here suggest (patch 1/3) to move the interrupt
> >registration and handling to the core rmi driver.
> 
> My concern with moving interrupt processing to the core is that not all
> transports report attn to the rmi core using an irq. The HID and SMBus
> transports which are currently in development, reside a little higher in the
> stack and attention is reported using different mechanisms. We moved
> interrupt handling to the transport drivers so that they could handle the
> differences in how attn is reported.
> 

I suspected that to be the case.

> This message has some of the previous discussion regarding interrupt
> processing:
> https://lkml.org/lkml/2015/11/28/123
> 
> Similarly, not all transports will need support for regulators. Implementing
> both in the transport drivers avoids the EPROBE_DEFER racing and avoids
> adding checks in the core to see if it needs to handle interrupts and manage
> regulators.
> 

So either we duplicate the regulator support in spi/i2c or we make them
optional in the core driver. Sounds like you prefer the prior, i.e. v1
of my patch.

Regards,
Bjorn