linux-kernel - Re: cx23885-input.c does in fact use a workqueue....

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Date:	Sun, 13 Feb 2011 20:33:55 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Andy Walls <awalls@...metrocast.net>
Cc:	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org, stoth@...nellabs.com
Subject: Re: cx23885-input.c does in fact use a workqueue....

On Sun, Feb 13, 2011 at 08:35:22PM -0500, Andy Walls wrote:
> Tejun,
> 
> I just noticed this commit:
> 
> commit 8c71778cbf2c8beaefaa2dee5478aa0622d96682
> Author: Tejun Heo <tj@...nel.org>
> Date:   Fri Dec 24 16:14:20 2010 +0100
> 
>     media/video: don't use flush_scheduled_work()
>     
>     This patch converts the remaining users of flush_scheduled_work() in
>     media/video.
>     
>     * bttv-input.c and cx23885-input.c don't use workqueue at all.  No
>       need to flush.
> [...]
> 
> 
> The cx23885 driver does in fact schedule work for IR input handling:
> 
> Here's where it is scheduled for CX23888 chips:
> 
> http://git.linuxtv.org/media_tree.git?a=blob;f=drivers/media/video/cx23885/cx23885-ir.c;h=7125247dd25558678c823ee3262675570c9aa630;hb=HEAD#l76
> 
> Here's where it is scheduled for CX23885 chips:
> 
> http://git.linuxtv.org/media_tree.git?a=blob;f=drivers/media/video/cx23885/cx23885-core.c;h=359882419b7f588b7c698dbcfb6a39ddb1603301;hb=HEAD#l1861
> 
> 
> The two different chips are handled slightly differently because
> 
> a. the CX23888 IR unit is accessable via a PCI register block.  The IR
> IRQ can be acknowledged with direct PCI register accesses in an
> interrupt context, and the IR pulse FIFO serviced later in a workqueue
> context.
> 
> b. the CX23885 IR unit is accessed over an I2C bus.  The CX23885 A/V IRQ
> has to be masked in an interrupt context (with PCI registers accesses).
> Then the CX23885 A/V unit's IR IRQ is ack'ed over I2C in a workqueue
> context and the IR pulse FIFO is also serviced over I2C in a workqueue
> context.
> 
> 
> So what should be done about the flush_scheduled_work()?  I think it
> belongs there.
> 

Convert to using threaded irq?

-- 
Dmitry
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