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 )=-
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