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- From: Mark Brown <broonie@kernel.org>
- Date: Wed, 10 Dec 2014 13:46:33 +0000
- Subject: [PATCH] spi: Only idle the message pump in the worker kthread
- In order to avoid the situation where the kthread is waiting for another
- context to make the hardware idle let the message pump know if it's being
- called from the worker thread context and if it isn't then defer to the
- worker thread instead of idling the hardware immediately. This will ensure
- that if this situation happens we block rather than busy waiting.
- Signed-off-by: Mark Brown <broonie@kernel.org>
- ---
- --- a/drivers/spi/spi.c
- +++ b/drivers/spi/spi.c
- @@ -875,8 +875,9 @@ void spi_finalize_current_transfer(struc
- EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
-
- /**
- - * spi_pump_messages - kthread work function which processes spi message queue
- - * @work: pointer to kthread work struct contained in the master struct
- + * __spi_pump_messages - function which processes spi message queue
- + * @master: master to process queue for
- + * @in_kthread: true if we are in the context of the message pump thread
- *
- * This function checks if there is any spi message in the queue that
- * needs processing and if so call out to the driver to initialize hardware
- @@ -886,10 +887,8 @@ EXPORT_SYMBOL_GPL(spi_finalize_current_t
- * inside spi_sync(); the queue extraction handling at the top of the
- * function should deal with this safely.
- */
- -static void spi_pump_messages(struct kthread_work *work)
- +static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
- {
- - struct spi_master *master =
- - container_of(work, struct spi_master, pump_messages);
- unsigned long flags;
- bool was_busy = false;
- int ret;
- @@ -916,6 +915,15 @@ static void spi_pump_messages(struct kth
- spin_unlock_irqrestore(&master->queue_lock, flags);
- return;
- }
- +
- + /* Only do teardown in the thread */
- + if (!in_kthread) {
- + queue_kthread_work(&master->kworker,
- + &master->pump_messages);
- + spin_unlock_irqrestore(&master->queue_lock, flags);
- + return;
- + }
- +
- master->busy = false;
- master->idling = true;
- spin_unlock_irqrestore(&master->queue_lock, flags);
- @@ -1004,6 +1012,18 @@ static void spi_pump_messages(struct kth
- }
- }
-
- +/**
- + * spi_pump_messages - kthread work function which processes spi message queue
- + * @work: pointer to kthread work struct contained in the master struct
- + */
- +static void spi_pump_messages(struct kthread_work *work)
- +{
- + struct spi_master *master =
- + container_of(work, struct spi_master, pump_messages);
- +
- + __spi_pump_messages(master, true);
- +}
- +
- static int spi_init_queue(struct spi_master *master)
- {
- struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
- @@ -2165,7 +2185,7 @@ static int __spi_sync(struct spi_device
- * can.
- */
- if (master->transfer == spi_queued_transfer)
- - spi_pump_messages(&master->pump_messages);
- + __spi_pump_messages(master, false);
-
- wait_for_completion(&done);
- status = message->status;
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