[PATCH v7 4/4] CMDQ: suspend/resume protection

HS Liao
2016-05-23T12:25:40Z

Add suspend/resume protection mechanism to prevent active task(s) in
suspend.

Signed-off-by: HS Liao <hs.liao@mediatek.com>
---
drivers/soc/mediatek/mtk-cmdq.c | 174 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 166 insertions(+), 8 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-cmdq.c b/drivers/soc/mediatek/mtk-cmdq.c
index f8c5d02..1a51cfb 100644
--- a/drivers/soc/mediatek/mtk-cmdq.c
+++ b/drivers/soc/mediatek/mtk-cmdq.c
@@ -39,6 +39,7 @@
#define CMDQ_CLK_NAME "gce"

#define CMDQ_CURR_IRQ_STATUS 0x010
+#define CMDQ_CURR_LOADED_THR 0x018
#define CMDQ_THR_SLOT_CYCLES 0x030

#define CMDQ_THR_BASE 0x100
@@ -125,6 +126,7 @@ enum cmdq_code {

enum cmdq_task_state {
TASK_STATE_BUSY, /* task running on a thread */
+ TASK_STATE_KILLED, /* task process being killed */
TASK_STATE_ERROR, /* task execution error */
TASK_STATE_DONE, /* task finished */
};
@@ -161,8 +163,12 @@ struct cmdq {
u32 irq;
struct workqueue_struct *task_release_wq;
struct cmdq_thread thread[CMDQ_THR_MAX_COUNT];
- spinlock_t exec_lock; /* for exec task */
+ atomic_t thread_usage;
+ struct mutex task_mutex; /* for task */
+ spinlock_t exec_lock; /* for exec */
struct clk *clock;
+ bool suspending;
+ bool suspended;
};

struct cmdq_subsys {
@@ -196,15 +202,27 @@ static int cmdq_eng_get_thread(u64 flag)
return CMDQ_THR_DISP_MISC_IDX;
}

-static void cmdq_task_release(struct cmdq_task *task)
+static void cmdq_task_release_unlocked(struct cmdq_task *task)
{
struct cmdq *cmdq = task->cmdq;

+ /* This func should be inside cmdq->task_mutex mutex */
+ lockdep_assert_held(&cmdq->task_mutex);
+
dma_free_coherent(cmdq->dev, task->command_size, task->va_base,
task->mva_base);
kfree(task);
}

+static void cmdq_task_release(struct cmdq_task *task)
+{
+ struct cmdq *cmdq = task->cmdq;
+
+ mutex_lock(&cmdq->task_mutex);
+ cmdq_task_release_unlocked(task);
+ mutex_unlock(&cmdq->task_mutex);
+}
+
static struct cmdq_task *cmdq_task_acquire(struct cmdq_rec *rec,
struct cmdq_task_cb cb)
{
@@ -576,6 +594,12 @@ static int cmdq_task_wait_and_release(struct cmdq_task *task)
dev_dbg(dev, "timeout!\n");

spin_lock_irqsave(&cmdq->exec_lock, flags);
+
+ if (cmdq->suspending && task->task_state == TASK_STATE_KILLED) {
+ spin_unlock_irqrestore(&cmdq->exec_lock, flags);
+ return 0;
+ }
+
if (task->task_state != TASK_STATE_DONE)
err = cmdq_task_handle_error_result(task);
if (list_empty(&thread->task_busy_list))
@@ -584,7 +608,9 @@ static int cmdq_task_wait_and_release(struct cmdq_task *task)

/* release regardless of success or not */
clk_disable_unprepare(cmdq->clock);
- cmdq_task_release(task);
+ atomic_dec(&cmdq->thread_usage);
+ if (!(task->cmdq->suspending && task->task_state == TASK_STATE_KILLED))
+ cmdq_task_release(task);

return err;
}
@@ -597,12 +623,28 @@ static void cmdq_task_wait_release_work(struct work_struct *work_item)
cmdq_task_wait_and_release(task);
}

-static void cmdq_task_wait_release_schedule(struct cmdq_task *task)
+static void cmdq_task_wait_release_schedule(struct cmdq *cmdq,
+ struct cmdq_task *task)
{
- struct cmdq *cmdq = task->cmdq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&cmdq->exec_lock, flags);
+
+ if (cmdq->suspending || cmdq->suspended) {
+ /*
+ * This means system is suspened between
+ * cmdq_task_submit_async() and
+ * cmdq_task_wait_release_schedule(), so return immediately.
+ * This task should be forced to remove by suspend flow.
+ */
+ spin_unlock_irqrestore(&cmdq->exec_lock, flags);
+ return;
+ }

INIT_WORK(&task->release_work, cmdq_task_wait_release_work);
queue_work(cmdq->task_release_wq, &task->release_work);
+
+ spin_unlock_irqrestore(&cmdq->exec_lock, flags);
}

static int cmdq_rec_realloc_cmd_buffer(struct cmdq_rec *rec, size_t size)
@@ -766,18 +808,31 @@ static int _cmdq_rec_flush(struct cmdq_rec *rec, struct cmdq_task **task_out,
struct cmdq_thread *thread;
int err;

+ mutex_lock(&cmdq->task_mutex);
+ if (rec->cmdq->suspending || rec->cmdq->suspended) {
+ dev_err(rec->cmdq->dev,
+ "%s is called after suspending\n", __func__);
+ mutex_unlock(&cmdq->task_mutex);
+ return -EPERM;
+ }
+
err = cmdq_rec_finalize(rec);
- if (err < 0)
+ if (err < 0) {
+ mutex_unlock(&cmdq->task_mutex);
return err;
+ }

task_cb.cb = cb;
task_cb.data = data;
*task_out = cmdq_task_acquire(rec, task_cb);
- if (!(*task_out))
+ if (!(*task_out)) {
+ mutex_unlock(&cmdq->task_mutex);
return -EFAULT;
+ }

thread = &cmdq->thread[cmdq_eng_get_thread((*task_out)->engine_flag)];
cmdq_task_exec(*task_out, thread);
+ mutex_unlock(&cmdq->task_mutex);
return 0;
}

@@ -802,7 +857,13 @@ int cmdq_rec_flush_async(struct cmdq_rec *rec, cmdq_async_flush_cb cb,
err = _cmdq_rec_flush(rec, &task, cb, data);
if (err < 0)
return err;
- cmdq_task_wait_release_schedule(task);
+
+ /*
+ * Task could be released in suspend flow,
+ * so we have to pass cmdq as parameter.
+ */
+ cmdq_task_wait_release_schedule(rec->cmdq, task);
+
return 0;
}
EXPORT_SYMBOL(cmdq_rec_flush_async);
@@ -814,6 +875,95 @@ void cmdq_rec_destroy(struct cmdq_rec *rec)
}
EXPORT_SYMBOL(cmdq_rec_destroy);

+static int cmdq_suspend(struct device *dev)
+{
+ struct cmdq *cmdq = dev_get_drvdata(dev);
+ u32 exec_threads;
+ int ref_count;
+ unsigned long flags;
+ struct cmdq_thread *thread;
+ struct cmdq_task *task, *tmp;
+ int i;
+
+ /* lock to prevent new tasks */
+ mutex_lock(&cmdq->task_mutex);
+ cmdq->suspending = true;
+
+ exec_threads = readl(cmdq->base + CMDQ_CURR_LOADED_THR);
+ ref_count = atomic_read(&cmdq->thread_usage);
+ if (ref_count <= 0 && !(exec_threads & CMDQ_THR_EXECUTING))
+ goto exit;
+
+ dev_err(dev, "suspend: kill running, tasks.\n");
+ dev_err(dev, "threads: 0x%08x, ref:%d\n", exec_threads, ref_count);
+
+ /*
+ * We need to ensure the system is ready to suspend,
+ * so kill all running CMDQ tasks and release HW engines.
+ */
+
+ /* remove all active tasks from thread and disable thread */
+ for (i = 0; i < ARRAY_SIZE(cmdq->thread); i++) {
+ thread = &cmdq->thread[i];
+
+ if (list_empty(&thread->task_busy_list))
+ continue;
+
+ /* prevent clk disable in release flow */
+ clk_prepare_enable(cmdq->clock);
+ cmdq_thread_suspend(cmdq, thread);
+
+ list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
+ list_entry) {
+ bool already_done = false;
+
+ spin_lock_irqsave(&cmdq->exec_lock, flags);
+ if (task->task_state == TASK_STATE_BUSY) {
+ /* still wait_event */
+ list_del(&task->list_entry);
+ task->task_state = TASK_STATE_KILLED;
+ } else {
+ /* almost finish its work */
+ already_done = true;
+ }
+ spin_unlock_irqrestore(&cmdq->exec_lock, flags);
+
+ /*
+ * TASK_STATE_KILLED will unlock
+ * wait_event_timeout in cmdq_task_wait_and_release(),
+ * so flush_work to wait auto release flow.
+ *
+ * We don't know processes running order,
+ * so call cmdq_task_release_unlocked() here to
+ * prevent releasing task before flush_work, and
+ * also to prevent deadlock of task_mutex.
+ */
+ if (!already_done) {
+ flush_work(&task->release_work);
+ cmdq_task_release_unlocked(task);
+ }
+ }
+
+ cmdq_thread_resume(thread);
+ cmdq_thread_disable(cmdq, &cmdq->thread[i]);
+ clk_disable_unprepare(cmdq->clock);
+ }
+
+exit:
+ cmdq->suspended = true;
+ cmdq->suspending = false;
+ mutex_unlock(&cmdq->task_mutex);
+ return 0; /* ALWAYS allow suspend */
+}
+
+static int cmdq_resume(struct device *dev)
+{
+ struct cmdq *cmdq = dev_get_drvdata(dev);
+
+ cmdq->suspended = false;
+ return 0;
+}
+
static int cmdq_remove(struct platform_device *pdev)
{
struct cmdq *cmdq = platform_get_drvdata(pdev);
@@ -852,6 +1002,7 @@ static int cmdq_probe(struct platform_device *pdev)
dev_dbg(dev, "cmdq device: addr:0x%p, va:0x%p, irq:%d\n",
dev, cmdq->base, cmdq->irq);

+ mutex_init(&cmdq->task_mutex);
spin_lock_init(&cmdq->exec_lock);
cmdq->task_release_wq = alloc_ordered_workqueue(
"%s", WQ_MEM_RECLAIM | WQ_HIGHPRI,
@@ -879,6 +1030,7 @@ static int cmdq_probe(struct platform_device *pdev)
err = PTR_ERR(cmdq->clock);
goto fail;
}
+
return 0;

fail:
@@ -886,6 +1038,11 @@ fail:
return err;
}

+static const struct dev_pm_ops cmdq_pm_ops = {
+ .suspend = cmdq_suspend,
+ .resume = cmdq_resume,
+};
+
static const struct of_device_id cmdq_of_ids[] = {
{.compatible = "mediatek,mt8173-gce",},
{}
@@ -897,6 +1054,7 @@ static struct platform_driver cmdq_drv = {
.driver = {
.name = CMDQ_DRIVER_DEVICE_NAME,
.owner = THIS_MODULE,
+ .pm = &cmdq_pm_ops,
.of_match_table = cmdq_of_ids,
}
};
--
1.9.1