[PATCH v3 08/15] drm/panfrost: Use a threaded IRQ for job interrupts

[Boris Brezillon]

This should avoid switching to interrupt context when the GPU is under
heavy use.

v3:
* Don't take the job_lock in panfrost_job_handle_irq()

Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_job.c | 53 ++++++++++++++++++-------
 1 file changed, 38 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c 
b/drivers/gpu/drm/panfrost/panfrost_job.c
index be8f68f63974..e0c479e67304 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -470,19 +470,12 @@ static const struct drm_sched_backend_ops 
panfrost_sched_ops = {
        .free_job = panfrost_job_free
 };
 
-static irqreturn_t panfrost_job_irq_handler(int irq, void *data)
+static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status)
 {
-       struct panfrost_device *pfdev = data;
-       u32 status = job_read(pfdev, JOB_INT_STAT);
        int j;
 
        dev_dbg(pfdev->dev, "jobslot irq status=%x\n", status);
 
-       if (!status)
-               return IRQ_NONE;
-
-       pm_runtime_mark_last_busy(pfdev->dev);
-
        for (j = 0; status; j++) {
                u32 mask = MK_JS_MASK(j);
 
@@ -519,7 +512,6 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void 
*data)
                if (status & JOB_INT_MASK_DONE(j)) {
                        struct panfrost_job *job;
 
-                       spin_lock(&pfdev->js->job_lock);
                        job = pfdev->jobs[j];
                        /* Only NULL if job timeout occurred */
                        if (job) {
@@ -531,21 +523,49 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void 
*data)
                                dma_fence_signal_locked(job->done_fence);
                                pm_runtime_put_autosuspend(pfdev->dev);
                        }
-                       spin_unlock(&pfdev->js->job_lock);
                }
 
                status &= ~mask;
        }
+}
 
+static irqreturn_t panfrost_job_irq_handler_thread(int irq, void *data)
+{
+       struct panfrost_device *pfdev = data;
+       u32 status = job_read(pfdev, JOB_INT_RAWSTAT);
+
+       while (status) {
+               pm_runtime_mark_last_busy(pfdev->dev);
+
+               spin_lock(&pfdev->js->job_lock);
+               panfrost_job_handle_irq(pfdev, status);
+               spin_unlock(&pfdev->js->job_lock);
+               status = job_read(pfdev, JOB_INT_RAWSTAT);
+       }
+
+       job_write(pfdev, JOB_INT_MASK,
+                 GENMASK(16 + NUM_JOB_SLOTS - 1, 16) |
+                 GENMASK(NUM_JOB_SLOTS - 1, 0));
        return IRQ_HANDLED;
 }
 
+static irqreturn_t panfrost_job_irq_handler(int irq, void *data)
+{
+       struct panfrost_device *pfdev = data;
+       u32 status = job_read(pfdev, JOB_INT_STAT);
+
+       if (!status)
+               return IRQ_NONE;
+
+       job_write(pfdev, JOB_INT_MASK, 0);
+       return IRQ_WAKE_THREAD;
+}
+
 static void panfrost_reset(struct work_struct *work)
 {
        struct panfrost_device *pfdev = container_of(work,
                                                     struct panfrost_device,
                                                     reset.work);
-       unsigned long flags;
        unsigned int i;
        bool cookie;
 
@@ -575,7 +595,7 @@ static void panfrost_reset(struct work_struct *work)
        /* All timers have been stopped, we can safely reset the pending state. 
*/
        atomic_set(&pfdev->reset.pending, 0);
 
-       spin_lock_irqsave(&pfdev->js->job_lock, flags);
+       spin_lock(&pfdev->js->job_lock);
        for (i = 0; i < NUM_JOB_SLOTS; i++) {
                if (pfdev->jobs[i]) {
                        pm_runtime_put_noidle(pfdev->dev);
@@ -583,7 +603,7 @@ static void panfrost_reset(struct work_struct *work)
                        pfdev->jobs[i] = NULL;
                }
        }
-       spin_unlock_irqrestore(&pfdev->js->job_lock, flags);
+       spin_unlock(&pfdev->js->job_lock);
 
        panfrost_device_reset(pfdev);
 
@@ -610,8 +630,11 @@ int panfrost_job_init(struct panfrost_device *pfdev)
        if (irq <= 0)
                return -ENODEV;
 
-       ret = devm_request_irq(pfdev->dev, irq, panfrost_job_irq_handler,
-                              IRQF_SHARED, KBUILD_MODNAME "-job", pfdev);
+       ret = devm_request_threaded_irq(pfdev->dev, irq,
+                                       panfrost_job_irq_handler,
+                                       panfrost_job_irq_handler_thread,
+                                       IRQF_SHARED, KBUILD_MODNAME "-job",
+                                       pfdev);
        if (ret) {
                dev_err(pfdev->dev, "failed to request job irq");
                return ret;
-- 
2.31.1