[PATCH v14 4/4] CMDQ: save more energy in idle

[HS Liao]

Use clk_disable_unprepare instead of clk_disable to save more energy
when CMDQ is idle.

Signed-off-by: HS Liao <hs.l...@mediatek.com>
---
 drivers/mailbox/mtk-cmdq.c | 54 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 46 insertions(+), 8 deletions(-)

diff --git a/drivers/mailbox/mtk-cmdq.c b/drivers/mailbox/mtk-cmdq.c
index daf5561..0bf30cb 100644
--- a/drivers/mailbox/mtk-cmdq.c
+++ b/drivers/mailbox/mtk-cmdq.c
@@ -29,6 +29,7 @@
 #include <linux/spinlock.h>
 #include <linux/suspend.h>
 #include <linux/timer.h>
+#include <linux/workqueue.h>
 
 #define CMDQ_THR_MAX_COUNT             3 /* main, sub, general(misc) */
 #define CMDQ_INST_SIZE                 8 /* instruction is 64-bit */
@@ -130,10 +131,16 @@ struct cmdq_task {
        struct cmdq_task_cb     cb;
 };
 
+struct cmdq_clk_release {
+       struct cmdq             *cmdq;
+       struct work_struct      release_work;
+};
+
 struct cmdq {
        struct mbox_controller  mbox;
        void __iomem            *base;
        u32                     irq;
+       struct workqueue_struct *clk_release_wq;
        struct cmdq_thread      thread[CMDQ_THR_MAX_COUNT];
        struct mutex            task_mutex;
        struct clk              *clock;
@@ -279,11 +286,19 @@ static void cmdq_thread_wait_end(struct cmdq_thread 
*thread,
 static void cmdq_task_exec(struct cmdq_task *task, struct cmdq_thread *thread)
 {
        struct cmdq *cmdq = task->cmdq;
-       unsigned long curr_pa, end_pa;
+       unsigned long curr_pa, end_pa, flags;
 
        task->thread = thread;
        if (list_empty(&thread->task_busy_list)) {
-               WARN_ON(clk_enable(cmdq->clock) < 0);
+               /*
+                * Unlock for clk prepare (sleeping function).
+                * We are safe to do that since we have task_mutex and
+                * only flush will add task.
+                */
+               spin_unlock_irqrestore(&thread->chan->lock, flags);
+               WARN_ON(clk_prepare_enable(cmdq->clock) < 0);
+               spin_lock_irqsave(&thread->chan->lock, flags);
+
                WARN_ON(cmdq_thread_reset(cmdq, thread) < 0);
 
                writel(task->pa_base, thread->base + CMDQ_THR_CURR_ADDR);
@@ -365,6 +380,26 @@ static void cmdq_task_handle_error(struct cmdq_task *task)
        cmdq_thread_resume(thread);
 }
 
+static void cmdq_clk_release_work(struct work_struct *work_item)
+{
+       struct cmdq_clk_release *clk_release = container_of(work_item,
+                       struct cmdq_clk_release, release_work);
+       struct cmdq *cmdq = clk_release->cmdq;
+
+       clk_disable_unprepare(cmdq->clock);
+       kfree(clk_release);
+}
+
+static void cmdq_clk_release_schedule(struct cmdq *cmdq)
+{
+       struct cmdq_clk_release *clk_release;
+
+       clk_release = kmalloc(sizeof(*clk_release), GFP_ATOMIC);
+       clk_release->cmdq = cmdq;
+       INIT_WORK(&clk_release->release_work, cmdq_clk_release_work);
+       queue_work(cmdq->clk_release_wq, &clk_release->release_work);
+}
+
 static void cmdq_thread_irq_handler(struct cmdq *cmdq,
                                    struct cmdq_thread *thread)
 {
@@ -414,7 +449,7 @@ static void cmdq_thread_irq_handler(struct cmdq *cmdq,
 
        if (list_empty(&thread->task_busy_list)) {
                cmdq_thread_disable(cmdq, thread);
-               clk_disable(cmdq->clock);
+               cmdq_clk_release_schedule(cmdq);
        } else {
                mod_timer(&thread->timeout,
                          jiffies + msecs_to_jiffies(CMDQ_TIMEOUT_MS));
@@ -473,7 +508,7 @@ static void cmdq_thread_handle_timeout(unsigned long data)
 
        cmdq_thread_resume(thread);
        cmdq_thread_disable(cmdq, thread);
-       clk_disable(cmdq->clock);
+       cmdq_clk_release_schedule(cmdq);
        spin_unlock_irqrestore(&thread->chan->lock, flags);
 }
 
@@ -761,7 +796,7 @@ static int cmdq_suspend(struct device *dev)
                msleep(20);
        }
 
-       clk_unprepare(cmdq->clock);
+       flush_workqueue(cmdq->clk_release_wq);
        return 0;
 }
 
@@ -769,7 +804,6 @@ static int cmdq_resume(struct device *dev)
 {
        struct cmdq *cmdq = dev_get_drvdata(dev);
 
-       WARN_ON(clk_prepare(cmdq->clock) < 0);
        cmdq->suspended = false;
        return 0;
 }
@@ -778,8 +812,8 @@ static int cmdq_remove(struct platform_device *pdev)
 {
        struct cmdq *cmdq = platform_get_drvdata(pdev);
 
+       destroy_workqueue(cmdq->clk_release_wq);
        mbox_controller_unregister(&cmdq->mbox);
-       clk_unprepare(cmdq->clock);
        return 0;
 }
 
@@ -898,8 +932,12 @@ static int cmdq_probe(struct platform_device *pdev)
                return err;
        }
 
+       cmdq->clk_release_wq = alloc_ordered_workqueue(
+                       "%s", WQ_MEM_RECLAIM | WQ_HIGHPRI,
+                       "cmdq_clk_release");
+
        platform_set_drvdata(pdev, cmdq);
-       WARN_ON(clk_prepare(cmdq->clock) < 0);
+
        return 0;
 }
 
-- 
1.9.1