diff options
Diffstat (limited to 'target/linux/generic/patches-3.18/092-03-spi-Only-idle-the-message-pump-in-the-worker-kthread.patch')
| -rw-r--r-- | target/linux/generic/patches-3.18/092-03-spi-Only-idle-the-message-pump-in-the-worker-kthread.patch | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/target/linux/generic/patches-3.18/092-03-spi-Only-idle-the-message-pump-in-the-worker-kthread.patch b/target/linux/generic/patches-3.18/092-03-spi-Only-idle-the-message-pump-in-the-worker-kthread.patch new file mode 100644 index 0000000..a5d85be --- /dev/null +++ b/target/linux/generic/patches-3.18/092-03-spi-Only-idle-the-message-pump-in-the-worker-kthread.patch @@ -0,0 +1,83 @@ +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; |