linux-kernel - Re: [RFC v2] regmap: regmap-irq: Add main status register support

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Message-ID: <20181218085803.GD2477@localhost.localdomain>
Date:   Tue, 18 Dec 2018 10:58:03 +0200
From:   Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     mazziesaccount@...il.com, gregkh@...uxfoundation.org,
        rafael@...nel.org, linux-kernel@...r.kernel.org,
        heikki.haikola@...rohmeurope.com, mikko.mutanen@...rohmeurope.com
Subject: Re: [RFC v2] regmap: regmap-irq: Add main status register support

On Mon, Dec 17, 2018 at 05:32:44PM +0000, Mark Brown wrote:
> On Fri, Dec 14, 2018 at 04:08:12PM +0200, Matti Vaittinen wrote:
> 
> > This is draft for approach proposed by Mark here:
> > http://lkml.iu.edu/hypermail/linux/kernel/1812.1/07117.html
> 
> > Pretty untested and diff is done against tree where the level active IRQ
> > support for regmap-irq was added. So please consider this just as a RFC
> > introducing the concept. I will format correct and better tested patch if
> > this is the preferred way to go.
> 
> Hrm, so the parsing code is indeed quite complicated.  I suspect it
> could be simplified if instead of trying to allocate just what's used it
> was a bit more wasteful and allocated the biggest arrays we might need
> but I'm not sure how much that'd really help so yeah, doing it the other
> way around might be better.

It might get a little bit simpler but not much I think. And the driver
interface could be a little bit simpler if we drop the support for
giving the "main bit mapping" as an array and only support giving the
main bits in the struct regmap_irqs. Then the num_main_status_bits,
num_main_regs and sub_reg_offsets could be made internal to regmap-irq.

OTOH dropping num_main_regs would add up one more thing requiring
dynamic allocation as we could not compute the number of main register
bits in advance.

I will proceed with the RFC v1 approach. Nothing prevents us from
implementing the v2 later if there is use-cases for that. But it will
take a while before I get this thing tested and user for it.
Additionally I guess we do need a bui-in from Lee as most of this kind
of devices with many sub blocks are likely to be represented as MFD
devices. I guess I should have included him in the recipient list for
the RFCs :/

Thanks for all the support this far!

Br,
	Matti Vaittinen

-- 
Matti Vaittinen
ROHM Semiconductors

~~~ "I don't think so," said Rene Descartes.  Just then, he vanished ~~~