linux-kernel - Re: [PATCH v3 09/11] serial: 8250_lpss: move Quark code from PCI driver

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Date:	Wed, 04 May 2016 20:43:12 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Bryan O'Donoghue <pure.logic@...us-software.ie>,
	Andy Shevchenko <andy.shevchenko@...il.com>
Cc:	Peter Hurley <peter@...leysoftware.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	Vinod Koul <vinod.koul@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	dmaengine <dmaengine@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Puustinen, Ismo" <ismo.puustinen@...el.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v3 09/11] serial: 8250_lpss: move Quark code from PCI
 driver

On Wed, 2016-05-04 at 15:51 +0100, Bryan O'Donoghue wrote:
> On Wed, 2016-05-04 at 14:20 +0300, Andy Shevchenko wrote:
> 
> > 
> > > 
> > > To move away from a valid/standard PCI probe routine into a new
> > > special
> > > LPSS/PCI shim (which the hardware doesn't actually mandate) I do
> > > think
> > > you should to setup the dependency CONFIG_8250_PCI =>
> > > CONFIG_8250_LPSS.
> > No, this is what we try avoiding
> Fine.
> 
> Could you then select CONFIG_SERIAL_8250_LPSS when
> CONFIG_X86_INTEL_QUARK is true - since it will be a dependency.

Answered to this in the other email, but can repeat my question. Do you
propose a new behaviour? Otherwise how does it work right now?

> 
> > 
> > If user selects CONFIG_SERIAL_8250_PCI, the CONFIG_SERIAL_8250_LPSS
> > will
> > be selected as well since it has same dependencies.
> I still think the change is not an obvious one i.e. LPSS (as an ACPI
> enumeration concept)

LPSS is a hardware concept. It might be not exactly one island on the
SoC, but it pretty much includes all those serial bus controllers and
DMA.

>  is not a requirement to enumerate on Quark X1000.
> 
> So I understand why you want to separate out the code from 8250_pci -
> however I think the *minimum* here should be a descriptive comment in
> kconfig listing which PCI-enumerated SoCs now require the 8250_LPSS
> work-around if just selecting 8250_LPSS isn't possible.
> 
> So how about listing out those SoCs - something like
> 
> "Selecting this option will enable handling of the extra features 
>  present on the UART found on Intel Braswell SoC and various  other
>  Intel platforms."
> 
> =>
> 
> "Selecting this option will enable handling of the extra features 
>  present on the UART found on
>  - Intel Braswell SoC
>  - Intel Quark x1000 SoC
>  - etc
> "
> If you make those changes - please add.

That would work for me. Will update it in next version. I'm still give a
time to answer for the questions above. I want us to be on the same
page.

> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...us-software.ie>

Thanks for review!

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy