target/linux/generic/patches-3.18/092-01-spi-Check-to-see-if-the-device-is-processing-a-messa.patch

   1 From: Mark Brown <broonie@kernel.org>
   2 Date: Tue, 9 Dec 2014 19:46:56 +0000
   3 Subject: [PATCH] spi: Check to see if the device is processing a message
   4  before we idle
   5
   6 cur_msg is updated under the queue lock and holds the message we are
   7 currently processing. Since currently we only ever do removals in the
   8 pump kthread it doesn't matter in what order we do things but we want
   9 to be able to push things out from the submitting thread so pull the
  10 check to see if we're currently handling a message before we check to
  11 see if the queue is idle.
  12
  13 Signed-off-by: Mark Brown <broonie@kernel.org>
  14 ---
  15
  16 --- a/drivers/spi/spi.c
  17 +++ b/drivers/spi/spi.c
  18 @@ -891,8 +891,16 @@ static void spi_pump_messages(struct kth
  19         bool was_busy = false;
  20         int ret;
  21
  22 -       /* Lock queue and check for queue work */
  23 +       /* Lock queue */
  24         spin_lock_irqsave(&master->queue_lock, flags);
  25 +
  26 +       /* Make sure we are not already running a message */
  27 +       if (master->cur_msg) {
  28 +               spin_unlock_irqrestore(&master->queue_lock, flags);
  29 +               return;
  30 +       }
  31 +
  32 +       /* Check if the queue is idle */
  33         if (list_empty(&master->queue) || !master->running) {
  34                 if (!master->busy) {
  35                         spin_unlock_irqrestore(&master->queue_lock, flags);
  36 @@ -916,11 +924,6 @@ static void spi_pump_messages(struct kth
  37                 return;
  38         }
  39
  40 -       /* Make sure we are not already running a message */
  41 -       if (master->cur_msg) {
  42 -               spin_unlock_irqrestore(&master->queue_lock, flags);
  43 -               return;
  44 -       }
  45         /* Extract head of queue */
  46         master->cur_msg =
  47                 list_first_entry(&master->queue, struct spi_message, queue);