linux-kernel - Re: [PATCH 1/3] misc: Add crossbar driver

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Message-ID: <51F0223E.4050008@ti.com>
Date:	Wed, 24 Jul 2013 13:51:42 -0500
From:	Nishanth Menon <nm@...com>
To:	Sricharan R <r.sricharan@...com>
CC:	Santosh Shilimkar <santosh.shilimkar@...com>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux-OMAP <linux-omap@...r.kernel.org>,
	ext Tony Lindgren <tony@...mide.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Rajendra Nayak <rnayak@...com>, Felipe Balbi <balbi@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH 1/3] misc: Add crossbar driver

On 07/24/2013 01:43 PM, Sricharan R wrote:
> On Wednesday 24 July 2013 10:17 PM, Nishanth Menon wrote:
>> On 07/24/2013 11:38 AM, Santosh Shilimkar wrote:
>>> On Wednesday 24 July 2013 12:08 PM, Nishanth Menon wrote:
>>>> That said, maybe a intermediate pinctrl approach might be more pragmatic and less theoretically flexible.
>>>> an option might be to "statically allocate" default number of interrupts to a domain - example:
>>>> * GIC IRQ 72->78 allotted to UARTs
>>>> * pinctrl mapping provided for those but only 6 can be used (rest are marked status="disabled" as default) at any given time (choice of pinctrl option determines GIC interrupt line to use)
>>>> * All modules will have a pinctrl definition to have a mapping - to avoid bootloader overriding default cross bar setting in ways un-expected by kernel.
>>>>
>>>> Does that sound fair trade off?
>>> This sounds better. That way we can get all the devices in the DT at least.
>>
>> Fair enough - if Linus and Tony are still ok with this approach to the problem, seeing a patch series with the effect would be beneficial.
>>
>   Ok, i will use this idea of certain number interrupts to groups.
> Yes on DRA7XX, we have about 160 gic lines and 320 irq crossbar device inputs contending for it.
> 1:2 and fully arbitrary.  But will we be really exhausting them ?
>
Depends on how we allocate :). The default arbitary allocation can be 
made more logical in your series ofcourse :).


-- 
Regards,
Nishanth Menon
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