[PATCH 1/2] mailbox: mtk-cmdq: Change GCE hardware timeout to software timeout
Jason-JH.Lin
jason-jh.lin at mediatek.com
Wed Jan 10 07:51:47 PST 2024
GCE axi_clock 156MHz, 1 tick cycle = 6.41ns.
The register CMDQ_INSTN_TIMEOUT_CYCLES is a GCE hardware configuration
for instruction timeout cycles. It's the cycles to issue instruction
timeout interrupt for wait and poll instructions.
This timeout setting is coarse-grain and has 100% uncertainty,
which means that if it is set to 16 cycles, the timeout will be reduced
from 16 * 2 = 32 cycles to 16 cycles.
If it is set to 64 cycles, the timeout will be reduced from 64 * 2 = 128
cycles to 64 cycles.
Current CMDQ_INSTN_TIMEOUT_CYCLES is set to 22, it means instruction
timeout is reduced from 2^22 * 2 * 6.41ns = 53.8ms to 26.9ms.
Since the max value of CMDQ_INSTN_TIMEOUT_CYCLES is 27, it means the max
instruction timeout is reduced from 2^27 * 2 * 6.41ns = 1720ms to 860ms.
It's not enough for the use case of ISP driver below:
GCE Thread A: wait for SOF and set event 1.
GCE Thread B: wait for event 1 and set event 2.
GCE Thread C: wait for event 2 and set event 3.
GCE Thread D: wait for event 3 and set event 4.
GCE Thread E: wait for event 4 and set EOF.
If all GCE Threads start at the same time, the latest GCE Thread E will
wait for event more than 2 seconds.
Therefore, we changed the hardware timeout to software timeout, making it
longer, more certain, and making it configurable by CMDQ client drivers.
Signed-off-by: Jason-JH.Lin <jason-jh.lin at mediatek.com>
---
drivers/mailbox/mtk-cmdq-mailbox.c | 172 +++++++++++++++++++++++
include/linux/mailbox/mtk-cmdq-mailbox.h | 3 +
2 files changed, 175 insertions(+)
diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
index de862e9137d5..89567f837513 100644
--- a/drivers/mailbox/mtk-cmdq-mailbox.c
+++ b/drivers/mailbox/mtk-cmdq-mailbox.c
@@ -12,6 +12,9 @@
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
+#include <linux/sched/clock.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/mailbox_controller.h>
@@ -64,6 +67,11 @@ struct cmdq_thread {
void __iomem *base;
struct list_head task_busy_list;
u32 priority;
+ u32 idx;
+ struct timer_list timeout;
+ u32 timeout_ms;
+ struct work_struct timeout_work;
+ u64 timer_mod;
};
struct cmdq_task {
@@ -83,6 +91,7 @@ struct cmdq {
struct cmdq_thread *thread;
struct clk_bulk_data clocks[CMDQ_GCE_NUM_MAX];
bool suspended;
+ struct workqueue_struct *timeout_wq;
};
struct gce_plat {
@@ -288,6 +297,158 @@ static void cmdq_thread_irq_handler(struct cmdq *cmdq,
if (list_empty(&thread->task_busy_list))
cmdq_thread_disable(cmdq, thread);
+
+ if (!task) {
+ cmdq_thread_disable(cmdq, thread);
+ pr_debug("empty task thread:%u", thread->idx);
+ } else {
+ mod_timer(&thread->timeout, jiffies +
+ msecs_to_jiffies(thread->timeout_ms));
+ thread->timer_mod = sched_clock();
+ pr_debug("mod_timer pkt:0x%p timeout:%u thread:%u",
+ task->pkt, thread->timeout_ms, thread->idx);
+ }
+}
+
+static bool cmdq_thread_timeout_exceed(struct cmdq_thread *thread)
+{
+ u64 duration;
+
+ /*
+ * If the first execution time stamp is smaller than timeout value,
+ * it is the last round of timeout. Skip it.
+ */
+ duration = div_s64(sched_clock() - thread->timer_mod, 1000000);
+ if (duration < thread->timeout_ms) {
+ mod_timer(&thread->timeout, jiffies +
+ msecs_to_jiffies(thread->timeout_ms - duration));
+ thread->timer_mod = sched_clock();
+ pr_debug("thread:%u mod time:%llu dur:%llu timeout not exceed",
+ thread->idx, thread->timer_mod, duration);
+ return false;
+ }
+
+ return true;
+}
+
+static void cmdq_thread_handle_timeout_work(struct work_struct *work_item)
+{
+ struct cmdq_thread *thread = container_of(work_item,
+ struct cmdq_thread, timeout_work);
+ struct cmdq *cmdq = container_of(thread->chan->mbox, struct cmdq, mbox);
+ struct cmdq_task *task, *tmp, *timeout_task = NULL;
+ unsigned long flags;
+ dma_addr_t pa_curr;
+ struct list_head removes;
+
+ INIT_LIST_HEAD(&removes);
+
+ spin_lock_irqsave(&thread->chan->lock, flags);
+
+ if (list_empty(&thread->task_busy_list)) {
+ spin_unlock_irqrestore(&thread->chan->lock, flags);
+ return;
+ }
+
+ /* Check before suspending thread to prevent performance penalty. */
+ if (!cmdq_thread_timeout_exceed(thread)) {
+ spin_unlock_irqrestore(&thread->chan->lock, flags);
+ return;
+ }
+
+ WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
+
+ /*
+ * Although IRQ is disabled, GCE continues to execute.
+ * It may have pending IRQ before GCE thread is suspended,
+ * so check this condition again.
+ */
+ cmdq_thread_irq_handler(cmdq, thread);
+
+ if (list_empty(&thread->task_busy_list)) {
+ pr_err("thread:%u empty after irq handle in timeout", thread->idx);
+ goto unlock_free_done;
+ }
+
+ /* After IRQ, the first task may change. */
+ if (!cmdq_thread_timeout_exceed(thread)) {
+ cmdq_thread_resume(thread);
+ goto unlock_free_done;
+ }
+
+ pr_err("timeout for thread:0x%p idx:%u", thread->base, thread->idx);
+
+ pa_curr = readl(thread->base + CMDQ_THR_CURR_ADDR) << cmdq->pdata->shift;
+ list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
+ list_entry) {
+ u32 task_end_pa = task->pa_base + task->pkt->cmd_buf_size;
+
+ if (pa_curr >= task->pa_base && pa_curr < task_end_pa) {
+ timeout_task = task;
+ break;
+ }
+
+ pr_info("ending not curr in timeout pkt:0x%p curr_pa:%pa", task->pkt, &pa_curr);
+ cmdq_task_exec_done(task, 0);
+ kfree(task);
+ }
+
+ if (timeout_task) {
+ spin_unlock_irqrestore(&thread->chan->lock, flags);
+
+ cmdq_task_exec_done(timeout_task, -ETIMEDOUT);
+
+ spin_lock_irqsave(&thread->chan->lock, flags);
+
+ task = list_first_entry_or_null(&thread->task_busy_list,
+ struct cmdq_task, list_entry);
+ if (timeout_task == task) {
+ cmdq_task_exec_done(task, -ETIMEDOUT);
+ kfree(task);
+ } else {
+ pr_err("task list changed");
+ }
+ }
+
+ task = list_first_entry_or_null(&thread->task_busy_list,
+ struct cmdq_task, list_entry);
+ if (task) {
+ mod_timer(&thread->timeout, jiffies +
+ msecs_to_jiffies(thread->timeout_ms));
+ thread->timer_mod = sched_clock();
+ cmdq_thread_reset(cmdq, thread);
+ cmdq_thread_resume(thread);
+ } else {
+ cmdq_thread_resume(thread);
+ cmdq_thread_disable(cmdq, thread);
+ pm_runtime_mark_last_busy(cmdq->mbox.dev);
+ }
+
+unlock_free_done:
+ spin_unlock_irqrestore(&thread->chan->lock, flags);
+
+ list_for_each_entry_safe(task, tmp, &removes, list_entry) {
+ list_del(&task->list_entry);
+ kfree(task);
+ }
+}
+
+static void cmdq_thread_handle_timeout(struct timer_list *t)
+{
+ struct cmdq_thread *thread = from_timer(thread, t, timeout);
+ struct cmdq *cmdq = container_of(thread->chan->mbox, struct cmdq, mbox);
+ unsigned long flags;
+ bool empty;
+
+ spin_lock_irqsave(&thread->chan->lock, flags);
+ empty = list_empty(&thread->task_busy_list);
+ spin_unlock_irqrestore(&thread->chan->lock, flags);
+
+ if (empty || work_pending(&thread->timeout_work))
+ return;
+
+ pr_debug("queue cmdq timeout thread:%u", thread->idx);
+ queue_work(cmdq->timeout_wq, &thread->timeout_work);
}
static irqreturn_t cmdq_irq_handler(int irq, void *dev)
@@ -426,6 +587,11 @@ static int cmdq_mbox_send_data(struct mbox_chan *chan, void *data)
writel(thread->priority, thread->base + CMDQ_THR_PRIORITY);
writel(CMDQ_THR_IRQ_EN, thread->base + CMDQ_THR_IRQ_ENABLE);
writel(CMDQ_THR_ENABLED, thread->base + CMDQ_THR_ENABLE_TASK);
+ if (thread->timeout_ms != CMDQ_NO_TIMEOUT) {
+ mod_timer(&thread->timeout, jiffies +
+ msecs_to_jiffies(thread->timeout_ms));
+ thread->timer_mod = sched_clock();
+ }
} else {
WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
curr_pa = readl(thread->base + CMDQ_THR_CURR_ADDR) <<
@@ -657,10 +823,14 @@ static int cmdq_probe(struct platform_device *pdev)
return -ENOMEM;
for (i = 0; i < cmdq->pdata->thread_nr; i++) {
+ cmdq->thread[i].idx = i;
cmdq->thread[i].base = cmdq->base + CMDQ_THR_BASE +
CMDQ_THR_SIZE * i;
+ cmdq->thread[i].timeout_ms = CMDQ_TIMEOUT_DEFAULT;
INIT_LIST_HEAD(&cmdq->thread[i].task_busy_list);
cmdq->mbox.chans[i].con_priv = (void *)&cmdq->thread[i];
+ timer_setup(&cmdq->thread[i].timeout, cmdq_thread_handle_timeout, 0);
+ INIT_WORK(&cmdq->thread[i].timeout_work, cmdq_thread_handle_timeout_work);
}
err = devm_mbox_controller_register(dev, &cmdq->mbox);
@@ -669,6 +839,8 @@ static int cmdq_probe(struct platform_device *pdev)
return err;
}
+ cmdq->timeout_wq = create_singlethread_workqueue("cmdq_timeout_handler");
+
platform_set_drvdata(pdev, cmdq);
WARN_ON(clk_bulk_prepare(cmdq->pdata->gce_num, cmdq->clocks));
diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h
index a8f0070c7aa9..4973b2ec37db 100644
--- a/include/linux/mailbox/mtk-cmdq-mailbox.h
+++ b/include/linux/mailbox/mtk-cmdq-mailbox.h
@@ -21,6 +21,9 @@
#define CMDQ_WFE_WAIT BIT(15)
#define CMDQ_WFE_WAIT_VALUE 0x1
+#define CMDQ_TIMEOUT_DEFAULT 1000
+#define CMDQ_NO_TIMEOUT 0xffffffff
+
/*
* WFE arg_b
* bit 0-11: wait value
--
2.18.0
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