55a912f43e
Changelog: * https://cdn.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.18.22 * https://cdn.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.18.23 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de> SVN-Revision: 47334
84 lines
2.9 KiB
Diff
84 lines
2.9 KiB
Diff
From: Mark Brown <broonie@kernel.org>
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Date: Wed, 10 Dec 2014 13:46:33 +0000
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Subject: [PATCH] spi: Only idle the message pump in the worker kthread
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In order to avoid the situation where the kthread is waiting for another
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context to make the hardware idle let the message pump know if it's being
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called from the worker thread context and if it isn't then defer to the
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worker thread instead of idling the hardware immediately. This will ensure
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that if this situation happens we block rather than busy waiting.
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Signed-off-by: Mark Brown <broonie@kernel.org>
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---
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--- a/drivers/spi/spi.c
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+++ b/drivers/spi/spi.c
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@@ -875,8 +875,9 @@ void spi_finalize_current_transfer(struc
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EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
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/**
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- * spi_pump_messages - kthread work function which processes spi message queue
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- * @work: pointer to kthread work struct contained in the master struct
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+ * __spi_pump_messages - function which processes spi message queue
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+ * @master: master to process queue for
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+ * @in_kthread: true if we are in the context of the message pump thread
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*
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* This function checks if there is any spi message in the queue that
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* needs processing and if so call out to the driver to initialize hardware
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@@ -886,10 +887,8 @@ EXPORT_SYMBOL_GPL(spi_finalize_current_t
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* inside spi_sync(); the queue extraction handling at the top of the
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* function should deal with this safely.
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*/
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-static void spi_pump_messages(struct kthread_work *work)
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+static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
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{
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- struct spi_master *master =
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- container_of(work, struct spi_master, pump_messages);
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unsigned long flags;
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bool was_busy = false;
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int ret;
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@@ -916,6 +915,15 @@ static void spi_pump_messages(struct kth
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spin_unlock_irqrestore(&master->queue_lock, flags);
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return;
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}
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+
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+ /* Only do teardown in the thread */
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+ if (!in_kthread) {
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+ queue_kthread_work(&master->kworker,
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+ &master->pump_messages);
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+ spin_unlock_irqrestore(&master->queue_lock, flags);
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+ return;
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+ }
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+
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master->busy = false;
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master->idling = true;
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spin_unlock_irqrestore(&master->queue_lock, flags);
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@@ -1004,6 +1012,18 @@ static void spi_pump_messages(struct kth
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}
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}
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+/**
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+ * spi_pump_messages - kthread work function which processes spi message queue
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+ * @work: pointer to kthread work struct contained in the master struct
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+ */
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+static void spi_pump_messages(struct kthread_work *work)
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+{
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+ struct spi_master *master =
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+ container_of(work, struct spi_master, pump_messages);
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+
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+ __spi_pump_messages(master, true);
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+}
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+
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static int spi_init_queue(struct spi_master *master)
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{
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struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
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@@ -2165,7 +2185,7 @@ static int __spi_sync(struct spi_device
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* can.
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*/
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if (master->transfer == spi_queued_transfer)
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- spi_pump_messages(&master->pump_messages);
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+ __spi_pump_messages(master, false);
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wait_for_completion(&done);
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status = message->status;
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