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Subject[RFC v4 4/4] CMDQ: suspend/resume protection
Date
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 | 289 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 282 insertions(+), 7 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-cmdq.c b/drivers/soc/mediatek/mtk-cmdq.c
index 2224459..63adb7c 100644
--- a/drivers/soc/mediatek/mtk-cmdq.c
+++ b/drivers/soc/mediatek/mtk-cmdq.c
@@ -51,6 +51,7 @@
#define CMDQ_CLK_NAME "gce"

#define CMDQ_CURR_IRQ_STATUS_OFFSET 0x010
+#define CMDQ_CURR_LOADED_THR_OFFSET 0x018
#define CMDQ_THR_SLOT_CYCLES_OFFSET 0x030

#define CMDQ_THR_BASE 0x100
@@ -150,6 +151,7 @@ enum cmdq_code {
enum cmdq_task_state {
TASK_STATE_IDLE, /* free task */
TASK_STATE_BUSY, /* task running on a thread */
+ TASK_STATE_KILLED, /* task process being killed */
TASK_STATE_ERROR, /* task execution error */
TASK_STATE_START_ERROR, /* fail to start task execution */
TASK_STATE_DONE, /* task finished */
@@ -198,6 +200,8 @@ struct cmdq_thread {

struct cmdq {
struct device *dev;
+ struct notifier_block pm_notifier;
+
void __iomem *base;
u32 irq;

@@ -220,8 +224,14 @@ struct cmdq {

/* mutex, spinlock, flag */
struct mutex task_mutex; /* for task list */
+ spinlock_t thread_lock; /* for cmdq hardware thread */
+ atomic_t thread_usage;
spinlock_t exec_lock; /* for exec task */

+ /* suspend */
+ atomic_t suspending;
+ bool suspended;
+
/* wait thread acquiring */
wait_queue_head_t thread_dispatch_queue;

@@ -377,14 +387,22 @@ static struct cmdq_task *cmdq_task_create(struct cmdq *cmdq)
return task;
}

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

- mutex_lock(&task->cmdq->task_mutex);
+ /* This func should be inside cmdq->task_mutex mutex */
+ lockdep_assert_held(&cmdq->task_mutex);
+
cmdq_task_free_command_buffer(task);
list_del(&task->list_entry);
kmem_cache_free(cmdq->task_cache, task);
+}
+
+static void cmdq_task_release_internal(struct cmdq_task *task)
+{
+ mutex_lock(&task->cmdq->task_mutex);
+ cmdq_task_release_unlocked(task);
mutex_unlock(&task->cmdq->task_mutex);
}

@@ -503,6 +521,7 @@ static struct cmdq_thread *cmdq_thread_get(struct cmdq *cmdq, u64 flag)
return NULL;

cmdq_clk_enable(cmdq);
+ atomic_inc(&cmdq->thread_usage);
return thread;
}

@@ -512,6 +531,7 @@ static void cmdq_thread_put(struct cmdq *cmdq, struct cmdq_thread *thread)
return;

cmdq_clk_disable(cmdq);
+ atomic_dec(&cmdq->thread_usage);
}

static int cmdq_thread_suspend(struct cmdq *cmdq, struct cmdq_thread *thread)
@@ -613,6 +633,80 @@ static int cmdq_thread_remove_task_by_index(struct cmdq_thread *thread,
return 0;
}

+static int cmdq_thread_force_remove_task(struct cmdq_task *task)
+{
+ struct cmdq *cmdq = task->cmdq;
+ struct cmdq_thread *thread = task->thread;
+ int status;
+ int cookie;
+ struct cmdq_task *exec_task;
+
+ status = cmdq_thread_suspend(cmdq, thread);
+
+ cmdq_thread_writel(thread, CMDQ_THR_NO_TIMEOUT,
+ CMDQ_THR_INST_CYCLES_OFFSET);
+
+ /* The cookie of the task currently being processed */
+ cookie = cmdq_thread_get_cookie(thread) + 1;
+
+ exec_task = thread->cur_task[cookie % CMDQ_MAX_TASK_IN_THREAD];
+ if (exec_task == task) {
+ dma_addr_t eoc_pa = task->mva_base + task->command_size - 16;
+
+ /* The task is executed now, set the PC to EOC for bypass */
+ cmdq_thread_writel(thread, eoc_pa, CMDQ_THR_CURR_ADDR_OFFSET);
+
+ thread->cur_task[cookie % CMDQ_MAX_TASK_IN_THREAD] = NULL;
+ task->task_state = TASK_STATE_KILLED;
+ } else {
+ int i, j;
+ u32 *task_base, *exec_task_base;
+
+ j = thread->task_count;
+ for (i = cookie; j > 0; j--, i++) {
+ i %= CMDQ_MAX_TASK_IN_THREAD;
+
+ exec_task = thread->cur_task[i];
+ if (!exec_task)
+ continue;
+
+ task_base = task->va_base;
+ exec_task_base = exec_task->va_base;
+ if ((exec_task_base[exec_task->num_cmd - 1] ==
+ CMDQ_JUMP_BY_OFFSET) &&
+ (exec_task_base[exec_task->num_cmd - 2] ==
+ CMDQ_JUMP_TO_BEGIN)) {
+ /* reached the last task */
+ break;
+ }
+
+ if (exec_task_base[exec_task->num_cmd - 2] ==
+ task->mva_base) {
+ /* fake EOC command */
+ exec_task_base[exec_task->num_cmd - 2] =
+ CMDQ_EOC_IRQ_EN;
+ exec_task_base[exec_task->num_cmd - 1] =
+ CMDQ_CODE_EOC << CMDQ_OP_CODE_SHIFT;
+
+ /* bypass the task */
+ exec_task_base[exec_task->num_cmd] =
+ task_base[task->num_cmd - 2];
+ exec_task_base[exec_task->num_cmd + 1] =
+ task_base[task->num_cmd - 1];
+
+ i = (i + 1) % CMDQ_MAX_TASK_IN_THREAD;
+
+ thread->cur_task[i] = NULL;
+ task->task_state = TASK_STATE_KILLED;
+ status = 0;
+ break;
+ }
+ }
+ }
+
+ return status;
+}
+
static struct cmdq_task *cmdq_thread_search_task_by_pc(
const struct cmdq_thread *thread, u32 pc)
{
@@ -958,6 +1052,25 @@ static void cmdq_handle_irq(struct cmdq *cmdq, int tid)
spin_unlock_irqrestore(&cmdq->exec_lock, flags);
}

+static int cmdq_resumed_notifier(struct cmdq *cmdq)
+{
+ unsigned long flags = 0L;
+
+ spin_lock_irqsave(&cmdq->thread_lock, flags);
+ cmdq->suspended = false;
+
+ /*
+ * during suspended, there may be queued tasks.
+ * we should process them if any.
+ */
+ queue_work(cmdq->task_consume_wq,
+ &cmdq->task_consume_wait_queue_item);
+
+ spin_unlock_irqrestore(&cmdq->thread_lock, flags);
+
+ return 0;
+}
+
static void cmdq_consume_waiting_list(struct work_struct *work)
{
struct cmdq *cmdq = container_of(work, struct cmdq,
@@ -965,6 +1078,13 @@ static void cmdq_consume_waiting_list(struct work_struct *work)
struct device *dev = cmdq->dev;
struct cmdq_task *task, *tmp;

+ /*
+ * when we're suspended,
+ * do not execute any tasks. delay & hold them.
+ */
+ if (cmdq->suspended)
+ return;
+
mutex_lock(&cmdq->task_mutex);

if (list_empty(&cmdq->task_wait_list)) {
@@ -1146,6 +1266,13 @@ static int cmdq_task_wait_result(struct cmdq_task *task)
*/
spin_lock_irqsave(&cmdq->exec_lock, flags);

+ /* suspend, so just return */
+ if (atomic_read(&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);

@@ -1223,7 +1350,8 @@ static int cmdq_task_wait_and_release(struct cmdq_task *task)

/* release regardless of success or not */
cmdq_thread_put(task->cmdq, task->thread);
- cmdq_task_release_internal(task);
+ if (!atomic_read(&task->cmdq->suspending))
+ cmdq_task_release_internal(task);

return err;
}
@@ -1281,7 +1409,7 @@ static int cmdq_task_submit(struct cmdq_command *command)
return err;
}

-static int cmdq_remove(struct platform_device *pdev)
+static void cmdq_deinitialize(struct platform_device *pdev)
{
struct cmdq *cmdq = platform_get_drvdata(pdev);
int i;
@@ -1313,8 +1441,6 @@ static int cmdq_remove(struct platform_device *pdev)

kmem_cache_destroy(cmdq->task_cache);
cmdq->task_cache = NULL;
-
- return 0;
}

static irqreturn_t cmdq_irq_handler(int irq, void *dev)
@@ -1346,6 +1472,7 @@ static int cmdq_initialize(struct cmdq *cmdq)

/* initial mutex, spinlock */
mutex_init(&cmdq->task_mutex);
+ spin_lock_init(&cmdq->thread_lock);
spin_lock_init(&cmdq->exec_lock);

/* initial wait queue for thread acquiring */
@@ -1646,6 +1773,126 @@ void cmdq_rec_destroy(struct cmdq_rec *rec)
}
EXPORT_SYMBOL(cmdq_rec_destroy);

+static int cmdq_pm_notifier_cb(struct notifier_block *nb, unsigned long event,
+ void *ptr)
+{
+ struct cmdq *cmdq = container_of(nb, struct cmdq, pm_notifier);
+
+ switch (event) {
+ case PM_SUSPEND_PREPARE:
+ /*
+ * Going to suspend the system
+ * The next stage is freeze process.
+ * We will queue all request in suspend callback,
+ * so don't care this stage
+ */
+ return NOTIFY_DONE;
+ case PM_POST_SUSPEND:
+ /*
+ * processes had resumed in previous stage
+ * (system resume callback)
+ * resume CMDQ driver to execute.
+ */
+ cmdq_resumed_notifier(cmdq);
+ return NOTIFY_OK;
+ default:
+ return NOTIFY_DONE;
+ }
+ return NOTIFY_DONE;
+}
+
+static int cmdq_suspend(struct device *dev)
+{
+ struct cmdq *cmdq = dev_get_drvdata(dev);
+ u32 exec_threads = readl(cmdq->base + CMDQ_CURR_LOADED_THR_OFFSET);
+ int ref_count;
+ unsigned long flags;
+
+ /*
+ * lock to prevent cmdq_core_consume_waiting_list() and
+ * cmdq_core_acquire_task(), i.e. no new active tasks
+ */
+ mutex_lock(&cmdq->task_mutex);
+
+ ref_count = atomic_read(&cmdq->thread_usage);
+ atomic_set(&cmdq->suspending, 1);
+
+ if (ref_count > 0 || exec_threads & CMDQ_THR_EXECUTING) {
+ struct cmdq_task *task, *tmp;
+ int i;
+
+ dev_err(dev, "suspend: other running, kill tasks.\n");
+ dev_err(dev, "threads:0x%08x, ref:%d, AL empty:%d, base:0x%p\n",
+ exec_threads, ref_count,
+ list_empty(&cmdq->task_active_list), cmdq->base);
+
+ /*
+ * We need to ensure the system is ready to suspend,
+ * so kill all running CMDQ tasks and release HW engines.
+ */
+
+ /* remove all active task from thread */
+ list_for_each_entry_safe(task, tmp, &cmdq->task_active_list,
+ list_entry) {
+ bool already_done = false;
+
+ if (!task->thread)
+ continue;
+
+ spin_lock_irqsave(&cmdq->exec_lock, flags);
+ if (task->task_state == TASK_STATE_BUSY) {
+ /* still wait_event */
+ cmdq_thread_force_remove_task(task);
+ 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_done(),
+ * 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->auto_release_work);
+ cmdq_task_release_unlocked(task);
+ }
+ }
+ dev_err(dev, "suspend: AL empty:%d\n",
+ list_empty(&cmdq->task_active_list));
+
+ /* disable all HW thread */
+ dev_err(dev, "suspend: disable all HW threads\n");
+ for (i = 0; i < CMDQ_MAX_THREAD_COUNT; i++)
+ cmdq_thread_disable(cmdq, &cmdq->thread[i]);
+
+ /* reset all cmdq_thread */
+ memset(&cmdq->thread[0], 0, sizeof(cmdq->thread));
+ }
+
+ spin_lock_irqsave(&cmdq->thread_lock, flags);
+ cmdq->suspended = true;
+ spin_unlock_irqrestore(&cmdq->thread_lock, flags);
+ atomic_set(&cmdq->suspending, 0);
+
+ mutex_unlock(&cmdq->task_mutex);
+
+ /* ALWAYS allow suspend */
+ return 0;
+}
+
+static int cmdq_resume(struct device *dev)
+{
+ return 0;
+}
+
static int cmdq_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -1697,13 +1944,40 @@ static int cmdq_probe(struct platform_device *pdev)
goto fail;
}

+ /* hibernation and suspend events */
+ cmdq->pm_notifier.notifier_call = cmdq_pm_notifier_cb;
+ cmdq->pm_notifier.priority = 5;
+ err = register_pm_notifier(&cmdq->pm_notifier);
+ if (err) {
+ dev_err(dev, "failed to register cmdq pm notifier\n");
+ goto fail;
+ }
+
return 0;

fail:
- cmdq_remove(pdev);
+ cmdq_deinitialize(pdev);
return err;
}

+static int cmdq_remove(struct platform_device *pdev)
+{
+ struct cmdq *cmdq = platform_get_drvdata(pdev);
+ int status;
+
+ status = unregister_pm_notifier(&cmdq->pm_notifier);
+ if (status)
+ dev_err(&pdev->dev, "unregister pm notifier failed\n");
+
+ cmdq_deinitialize(pdev);
+ return 0;
+}
+
+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",},
{}
@@ -1715,6 +1989,7 @@ 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,
}
};
--
1.7.9.5
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