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

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Date:	Sun, 13 Feb 2011 20:35:22 -0500
From:	Andy Walls <awalls@...metrocast.net>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	stoth@...nellabs.com
Subject: cx23885-input.c does in fact use a workqueue....

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.

Regards,
Andy

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