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

From: Tejun Heo
Date: Mon Feb 14 2011 - 06:03:49 EST


Hello,

On Sun, Feb 13, 2011 at 08:33:55PM -0800, Dmitry Torokhov wrote:
> > 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

Ah, sorry about missing those.

> > 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?

Or

1. Just flush the work items explicitly using flush_work_sync().

2. Create a dedicated workqueue to serve as flushing domain.

The first would look like the following. Does this look correct?

Thanks.

diff --git a/drivers/media/video/cx23885/cx23885-input.c b/drivers/media/video/cx23885/cx23885-input.c
index 199b996..e27cedb 100644
--- a/drivers/media/video/cx23885/cx23885-input.c
+++ b/drivers/media/video/cx23885/cx23885-input.c
@@ -229,6 +229,9 @@ static void cx23885_input_ir_stop(struct cx23885_dev *dev)
v4l2_subdev_call(dev->sd_ir, ir, rx_s_parameters, &params);
v4l2_subdev_call(dev->sd_ir, ir, rx_g_parameters, &params);
}
+ flush_work_sync(&dev->cx25840_work);
+ flush_work_sync(&dev->ir_rx_work);
+ flush_work_sync(&dev->ir_tx_work);
}

static void cx23885_input_ir_close(struct rc_dev *rc)

--
tejun
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