>On Thursday, January 16, 2014 5:31 AM, Ian Abbott <abbotti@xxxxxxxxx> wrote:
>On 2014-01-15 19:22, Chase Southwood wrote:
>> This patch for ni_mio_common.c changes out a while loop for a timeout,
>> which is preferred.
>>
>> Signed-off-by: Chase Southwood <chase.southwood@xxxxxxxxx>
>> ---
>>
>> Hartley,
>> I sincerely apologize for the obvious mistake, I thought I had built it
>> but clearly I made a mistake somewhere, as your observation is exactly
>> correct. It is now fixed.
>>
>> Thanks,
>> Chase Southwood
>>
>> 2: Changed from simple clean-up to swapping a timeout in for a while loop.
>>
>> 3: Removed extra counter variable, and added error checking.
>>
>> 4: No longer using counter variable, using jiffies instead.
>>
>> 5: udelay for 10u, instead of 1u.
>>
>> 6: Scrap udelay entirely, in favor of cpu_relax. Include asm/processor.h
>> in order to use cpu_relax.
>>
>> 7: Fix typo (msec vs msecs).
>>
>> drivers/staging/comedi/drivers/ni_mio_common.c | 12 +++++++++++-
>> 1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c >b/drivers/staging/comedi/drivers/ni_mio_common.c
>> index 457b884..ab7a74c 100644
>> --- a/drivers/staging/comedi/drivers/ni_mio_common.c
>> +++ b/drivers/staging/comedi/drivers/ni_mio_common.c
>> @@ -55,6 +55,7 @@
>> #include <linux/interrupt.h>
>> #include <linux/sched.h>
>> #include <linux/delay.h>
>> +#include <asm/processor.h>
>> #include "8255.h"
>> #include "mite.h"
>> #include "comedi_fc.h"
>> @@ -687,12 +688,21 @@ static void ni_clear_ai_fifo(struct comedi_device *dev)
>> {
>> const struct ni_board_struct *board = comedi_board(dev);
>> struct ni_private *devpriv = dev->private;
>> + unsigned long timeout;
>>
>> if (board->reg_type == ni_reg_6143) {
>> /* Flush the 6143 data FIFO */
>> ni_writel(0x10, AIFIFO_Control_6143); /* Flush fifo */
>> ni_writel(0x00, AIFIFO_Control_6143); /* Flush fifo */
>> - while (ni_readl(AIFIFO_Status_6143) & 0x10) ; /* Wait for complete */
>> + /* Wait for complete */
>> + timeout = jiffies + msecs_to_jiffies(500);
>> + while (ni_readl(AIFIFO_Status_6143) & 0x10) {
>> + if (time_after(jiffies, timeout)) {
>> + comedi_error(dev, "FIFO flush timeout.");
>> + break;
>> + }
>> + cpu_relax();
>> + }
>> } else {
>> devpriv->stc_writew(dev, 1, ADC_FIFO_Clear);
>> if (board->reg_type == ni_reg_625x) {
>>
>Sorry this is your worst nightmare, Chase. Your patch is great and has
>been modified in all the ways various people have suggested, but I don't
>think it is suitable.
>
>After examining the code, it turns out ni_clear_ai_fifo() is sometimes
>called from an interrupt service routine and I don't think you can wait
>for jiffies to change in that case. I think we need to go back to your
>PATCH v2 and fix up the checkpatch.pl warning that Greg mentioned.
>
>Sorry about that.
>
>--
>-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
>-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
It's absolutely no problem. I'll get v2 cleaned up and sent out right away!
Thanks,
Chase Southwood
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