----- Original Message -----
From: "Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx>
To: "Madhusudhan Chikkature" <madhu.cr@xxxxxx>
Cc: <gadiyar@xxxxxx>; <johnpol@xxxxxxxxxxx>; <linux-kernel@xxxxxxxxxxxxxxx>; <linux-omap@xxxxxxxxxxxxxxx>
Sent: Monday, October 13, 2008 9:23 PM
Subject: Re: [PATCH 1/5] HDQ Driver for OMAP2430/3430
>> On Mon, 13 Oct 2008 18:55:43 +0530 "Madhusudhan Chikkature" <madhu.cr@xxxxxx> wrote:
>>
>> ----- Original Message -----
>> From: "Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx>
>> To: "Gadiyar, Anand" <gadiyar@xxxxxx>
>> Cc: <johnpol@xxxxxxxxxxx>; <linux-kernel@xxxxxxxxxxxxxxx>; <linux-omap@xxxxxxxxxxxxxxx>; <madhu.cr@xxxxxx>
>> Sent: Saturday, October 11, 2008 2:08 AM
>> Subject: Re: [PATCH 1/5] HDQ Driver for OMAP2430/3430
>>
>>
>> >> + /* set the GO bit */
>> >> + hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, OMAP_HDQ_CTRL_STATUS_GO,
>> >> + OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO);
>> >> + /* wait for the TXCOMPLETE bit */
>> >> + ret = wait_event_interruptible_timeout(hdq_wait_queue,
>> >> + hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
>> >> + if (ret < 0) {
>> >> + dev_dbg(hdq_data->dev, "wait interrupted");
>> >> + return -EINTR;
>> >> + }
>> >
>> > Is this desirable? The user hits ^C and the driver bails out?
>> >
>> > I assume so, but was this tested?
>>
>> Andrew, What is the test scenario you mean here? A user hitting ^C when the driver is waiting for the TXCOMPLETE bit?
>
> Yes.
>
Yes. It is desired to return an error if the condition in the wait is not met. I need to change the check for return value to check for zero and neg value.
I spent some time to test this perticular scenario.I could not really see any impact of hitting ^C when an application is
transfering data in the background. When the h/w is programmed to transfer data and the driver issues a wait, I see that
TXCOMPLETE interrupt comes immediately and wakes up as expected.
So guess I am unable to hit ^C exactly when the driver is waiting in wait_event_interruptible_timeout(before the condition
is met) for it to catch the signal. Is it generally suggested to use wait_event_timeout so that ^C signal is not caught?
Regards,
Madhu
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