From mboxrd@z Thu Jan  1 00:00:00 1970
From: archit taneja <archit@ti.com>
Subject: Re: OMAP: DSS2: Common IRQ handler for all OMAPs
Date: Tue, 15 Feb 2011 14:17:56 +0530
Message-ID: <4D5A3DBC.9070506@ti.com>
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To: "Valkeinen, Tomi" <tomi.valkeinen@ti.com>
Cc: "Balbi, Felipe" <balbi@ti.com>, "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>

Hi,

On Tuesday 15 February 2011 02:07 PM, Valkeinen, Tomi wrote:
> On Tue, 2011-02-15 at 02:30 -0600, Taneja, Archit wrote:
>> Hi,
>>
>> On Tuesday 15 February 2011 12:57 PM, Valkeinen, Tomi wrote:
>>
>> <snip>
>>
>>> I meant something like this:
>>>
>>> dispc.c:
>>>
>>> dispc_init()
>>> {
>>> 	/* did we have a pdev for dispc? if not, this needs to be dss.pdev */
>>> 	request_irq(platform_get_irq(dispc.pdev, 0), irq_handler, IRQF_SHARED, "dispc irq", foo);
>>> }
>>>
>>> irq_handler()
>>> {
>>> 	if (irq_can_be_shared) {
>>> 		check if the irq is for us. exit if not;
>>> 	}
>>>
>>> 	handle;
>>> }
>>>
>>> dsi.c:
>>>
>>> dsi_init()
>>> {
>>> 	request_irq(platform_get_irq(dsi.pdev, 0), irq_handler, IRQF_SHARED, "dsi irq", foo);
>>> }
>>>
>>> irq_handler()
>>> {
>>> 	if (irq_can_be_shared) {
>>> 		check if the irq is for us. exit if not;
>>> 	}
>>>
>>> 	handle;
>>> }
>>>
>>
>> This approach looks clean, but isn't IRQF_SHARED used the other way
>> around. One irq line and multiple handlers?
>
> That is the case here, isn't it (on omap3)? One interrupt line (the DSS
> irq, the same returned both from dsi.pdev and dispc.pdev), and two
> handlers, one in dispc and one in dsi? Or what do you mean?

Okay, so for OMAP3 we should populate dsi.pdev and dispc.pdev in such a 
way that they return the single irq line number for DSS. And for OMAP4,
the separate line numbers will go for the modules anyway.

How do differentiate with the common handler now? It will be dirty if we 
have checks on the irq_line. Could we pass the pdev as the arg to 
differentiate the source?

>
> On omap2 there's no dsi code ran, so dispc is the only one requesting
> the irq, and thus IRQF_SHARED is extra. In omap4 there are separate irq
> lines (dsi.pdev and dispc.pdev return different irqs), and so
> IRQF_SHARED is again extra. But I don't see any harm in IRQF_SHARED even
> in omap2/4.
>
>   Tomi
>
>

Regards,
Archit