From: Jiri Slaby Return ERR even if there are pending data, but hw is not running. Do not decrement count in poll, do it in ioctl, where data are actually read. Signed-off-by: Jiri Slaby Signed-off-by: Andrew Morton --- drivers/misc/phantom.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff -puN drivers/misc/phantom.c~misc-phantom-fix-poll drivers/misc/phantom.c --- a/drivers/misc/phantom.c~misc-phantom-fix-poll +++ a/drivers/misc/phantom.c @@ -169,6 +169,7 @@ static long phantom_ioctl(struct file *f for (i = 0; i < m; i++) if (rs.mask & BIT(i)) rs.values[i] = ioread32(dev->iaddr + i); + atomic_set(&dev->counter, 0); spin_unlock_irqrestore(&dev->regs_lock, flags); if (copy_to_user(argp, &rs, sizeof(rs))) @@ -254,11 +255,12 @@ static unsigned int phantom_poll(struct pr_debug("phantom_poll: %d\n", atomic_read(&dev->counter)); poll_wait(file, &dev->wait, wait); - if (atomic_read(&dev->counter)) { + + if (!(dev->status & PHB_RUNNING)) + mask = POLLERR; + else if (atomic_read(&dev->counter)) mask = POLLIN | POLLRDNORM; - atomic_dec(&dev->counter); - } else if ((dev->status & PHB_RUNNING) == 0) - mask = POLLIN | POLLRDNORM | POLLERR; + pr_debug("phantom_poll end: %x/%d\n", mask, atomic_read(&dev->counter)); return mask; _