From: Steven Price <steven.pr...@arm.com>

The hardware has a set of '_NEXT' registers that can hold a second job
while the first is executing. Make use of these registers to enqueue a
second job per slot.

v2:
* Make sure non-faulty jobs get properly paused/resumed on GPU reset

Signed-off-by: Steven Price <steven.pr...@arm.com>
Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_device.h |   2 +-
 drivers/gpu/drm/panfrost/panfrost_job.c    | 311 ++++++++++++++++-----
 2 files changed, 242 insertions(+), 71 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h 
b/drivers/gpu/drm/panfrost/panfrost_device.h
index 95e6044008d2..a87917b9e714 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -101,7 +101,7 @@ struct panfrost_device {
 
        struct panfrost_job_slot *js;
 
-       struct panfrost_job *jobs[NUM_JOB_SLOTS];
+       struct panfrost_job *jobs[NUM_JOB_SLOTS][2];
        struct list_head scheduled_jobs;
 
        struct panfrost_perfcnt *perfcnt;
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c 
b/drivers/gpu/drm/panfrost/panfrost_job.c
index 1b5c636794a1..888eceed227f 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -4,6 +4,7 @@
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/dma-resv.h>
@@ -41,6 +42,7 @@ struct panfrost_queue_state {
 };
 
 struct panfrost_job_slot {
+       int irq;
        struct panfrost_queue_state queue[NUM_JOB_SLOTS];
        spinlock_t job_lock;
 };
@@ -148,9 +150,43 @@ static void panfrost_job_write_affinity(struct 
panfrost_device *pfdev,
        job_write(pfdev, JS_AFFINITY_NEXT_HI(js), affinity >> 32);
 }
 
+static struct panfrost_job *
+panfrost_dequeue_job(struct panfrost_device *pfdev, int slot)
+{
+       struct panfrost_job *job = pfdev->jobs[slot][0];
+
+       pfdev->jobs[slot][0] = pfdev->jobs[slot][1];
+       pfdev->jobs[slot][1] = NULL;
+
+       return job;
+}
+
+static unsigned int
+panfrost_enqueue_job(struct panfrost_device *pfdev, int slot,
+                    struct panfrost_job *job)
+{
+       if (!pfdev->jobs[slot][0]) {
+               pfdev->jobs[slot][0] = job;
+               return 0;
+       }
+
+       WARN_ON(pfdev->jobs[slot][1]);
+       pfdev->jobs[slot][1] = job;
+       return 1;
+}
+
+static u32
+panfrost_get_job_chain_flag(const struct panfrost_job *job)
+{
+       struct panfrost_fence *f = to_panfrost_fence(job->done_fence);
+
+       return (f->seqno & 1) ? JS_CONFIG_JOB_CHAIN_FLAG : 0;
+}
+
 static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 {
        struct panfrost_device *pfdev = job->pfdev;
+       unsigned int subslot;
        u32 cfg;
        u64 jc_head = job->jc;
        int ret;
@@ -176,7 +212,8 @@ static void panfrost_job_hw_submit(struct panfrost_job 
*job, int js)
         * start */
        cfg |= JS_CONFIG_THREAD_PRI(8) |
                JS_CONFIG_START_FLUSH_CLEAN_INVALIDATE |
-               JS_CONFIG_END_FLUSH_CLEAN_INVALIDATE;
+               JS_CONFIG_END_FLUSH_CLEAN_INVALIDATE |
+               panfrost_get_job_chain_flag(job);
 
        if (panfrost_has_hw_feature(pfdev, HW_FEATURE_FLUSH_REDUCTION))
                cfg |= JS_CONFIG_ENABLE_FLUSH_REDUCTION;
@@ -190,10 +227,17 @@ static void panfrost_job_hw_submit(struct panfrost_job 
*job, int js)
                job_write(pfdev, JS_FLUSH_ID_NEXT(js), job->flush_id);
 
        /* GO ! */
-       dev_dbg(pfdev->dev, "JS: Submitting atom %p to js[%d] with head=0x%llx",
-                               job, js, jc_head);
 
-       job_write(pfdev, JS_COMMAND_NEXT(js), JS_COMMAND_START);
+       spin_lock(&pfdev->js->job_lock);
+       subslot = panfrost_enqueue_job(pfdev, js, job);
+       /* Don't queue the job if a reset is in progress */
+       if (!atomic_read(&pfdev->reset.pending)) {
+               job_write(pfdev, JS_COMMAND_NEXT(js), JS_COMMAND_START);
+               dev_dbg(pfdev->dev,
+                       "JS: Submitting atom %p to js[%d][%d] with head=0x%llx 
AS %d",
+                       job, js, subslot, jc_head, cfg & 0xf);
+       }
+       spin_unlock(&pfdev->js->job_lock);
 }
 
 static void panfrost_acquire_object_fences(struct drm_gem_object **bos,
@@ -351,7 +395,11 @@ static struct dma_fence *panfrost_job_run(struct 
drm_sched_job *sched_job)
        if (unlikely(job->base.s_fence->finished.error))
                return NULL;
 
-       pfdev->jobs[slot] = job;
+       /* Nothing to execute: can happen if the job has finished while
+        * we were resetting the GPU.
+        */
+       if (!job->jc)
+               return NULL;
 
        fence = panfrost_fence_create(pfdev, slot);
        if (IS_ERR(fence))
@@ -475,25 +523,67 @@ static const struct drm_sched_backend_ops 
panfrost_sched_ops = {
 
 static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status)
 {
-       int j;
+       struct panfrost_job *done[NUM_JOB_SLOTS][2] = {};
+       struct panfrost_job *failed[NUM_JOB_SLOTS] = {};
+       u32 js_state, js_events = 0;
+       unsigned int i, j;
 
-       dev_dbg(pfdev->dev, "jobslot irq status=%x\n", status);
+       while (status) {
+               for (j = 0; j < NUM_JOB_SLOTS; j++) {
+                       if (status & JOB_INT_MASK_DONE(j)) {
+                               if (done[j][0]) {
+                                       done[j][1] = 
panfrost_dequeue_job(pfdev, j);
+                                       WARN_ON(!done[j][1]);
+                               } else {
+                                       done[j][0] = 
panfrost_dequeue_job(pfdev, j);
+                                       WARN_ON(!done[j][0]);
+                               }
+                       }
 
-       for (j = 0; status; j++) {
-               u32 mask = MK_JS_MASK(j);
+                       if (status & JOB_INT_MASK_ERR(j)) {
+                               /* Cancel the next submission. Will be submitted
+                                * after we're done handling this failure if
+                                * there's no reset pending.
+                                */
+                               job_write(pfdev, JS_COMMAND_NEXT(j), 
JS_COMMAND_NOP);
+                               failed[j] = panfrost_dequeue_job(pfdev, j);
+                       }
+               }
 
-               if (!(status & mask))
+               /* JS_STATE is sampled when JOB_INT_CLEAR is written.
+                * For each BIT(slot) or BIT(slot + 16) bit written to
+                * JOB_INT_CLEAR, the corresponding bits in JS_STATE
+                * (BIT(slot) and BIT(slot + 16)) are updated, but this
+                * is racy. If we only have one job done at the time we
+                * read JOB_INT_RAWSTAT but the second job fails before we
+                * clear the status, we end up with a status containing
+                * only the DONE bit and consider both jobs as DONE since
+                * JS_STATE reports both NEXT and CURRENT as inactive.
+                * To prevent that, let's repeat this clear+read steps
+                * until status is 0.
+                */
+               job_write(pfdev, JOB_INT_CLEAR, status);
+               js_state = job_read(pfdev, JOB_INT_JS_STATE);
+               js_events |= status;
+               status = job_read(pfdev, JOB_INT_RAWSTAT);
+       }
+
+       for (j = 0; j < NUM_JOB_SLOTS; j++) {
+               if (!(js_events & MK_JS_MASK(j)))
                        continue;
 
-               job_write(pfdev, JOB_INT_CLEAR, mask);
-
-               if (status & JOB_INT_MASK_ERR(j)) {
-                       enum panfrost_queue_status old_status;
+               if (failed[j]) {
                        u32 js_status = job_read(pfdev, JS_STATUS(j));
                        int error = panfrost_exception_to_error(js_status);
                        const char *exception_name = 
panfrost_exception_name(js_status);
 
-                       job_write(pfdev, JS_COMMAND_NEXT(j), JS_COMMAND_NOP);
+                       if (js_status == DRM_PANFROST_EXCEPTION_STOPPED) {
+                               /* Update the job head so we can resume */
+                               failed[j]->jc = job_read(pfdev, JS_TAIL_LO(j)) |
+                                               ((u64)job_read(pfdev, 
JS_TAIL_HI(j)) << 32);
+                       } else {
+                               failed[j]->jc = 0;
+                       }
 
                        if (!error) {
                                dev_dbg(pfdev->dev, "js interrupt, js=%d, 
status=%s, head=0x%x, tail=0x%x",
@@ -505,51 +595,68 @@ static void panfrost_job_handle_irq(struct 
panfrost_device *pfdev, u32 status)
                                        j, exception_name,
                                        job_read(pfdev, JS_HEAD_LO(j)),
                                        job_read(pfdev, JS_TAIL_LO(j)));
+                               dma_fence_set_error(failed[j]->done_fence, 
error);
                        }
 
-                       /* If we need a reset, signal it to the reset handler,
-                        * otherwise, update the fence error field and signal
-                        * the job fence.
+                       panfrost_mmu_as_put(pfdev, failed[j]->file_priv->mmu);
+                       panfrost_devfreq_record_idle(&pfdev->pfdevfreq);
+
+                       dma_fence_signal_locked(failed[j]->done_fence);
+                       pm_runtime_put_autosuspend(pfdev->dev);
+
+                       if (panfrost_exception_needs_reset(pfdev, js_status))
+                               panfrost_device_schedule_reset(pfdev);
+               } else if (pfdev->jobs[j][0] && !(js_state & MK_JS_MASK(j))) {
+                       /* When the current job doesn't fail, the JM dequeues
+                        * the next job without waiting for an ACK, this means
+                        * we can have 2 jobs dequeued and only catch the
+                        * interrupt when the second one is done. If both slots
+                        * are inactive, but one job remains in pfdev->jobs[j],
+                        * consider it done. Of course that doesn't apply if a
+                        * failure happened since we cancelled execution of the
+                        * job in _NEXT (see above).
                         */
-                       if (panfrost_exception_needs_reset(pfdev, js_status)) {
-                               /*
-                                * When the queue is being restarted we don't 
report
-                                * faults directly to avoid races between the 
timeout
-                                * and reset handlers. 
panfrost_scheduler_start() will
-                                * call drm_sched_fault() after the queue has 
been
-                                * started if status == FAULT_PENDING.
-                                */
-                               old_status = 
atomic_cmpxchg(&pfdev->js->queue[j].status,
-                                                           
PANFROST_QUEUE_STATUS_STARTING,
-                                                           
PANFROST_QUEUE_STATUS_FAULT_PENDING);
-                               if (old_status == PANFROST_QUEUE_STATUS_ACTIVE)
-                                       
drm_sched_fault(&pfdev->js->queue[j].sched);
-                       } else {
-                               dma_fence_set_error(pfdev->jobs[j]->done_fence,
-                                                   
panfrost_exception_to_error(js_status));
-                               status |= JOB_INT_MASK_DONE(j);
-                       }
+                       if (WARN_ON(!done[j][0]))
+                               done[j][0] = panfrost_dequeue_job(pfdev, j);
+                       else
+                               done[j][1] = panfrost_dequeue_job(pfdev, j);
                }
 
-               if (status & JOB_INT_MASK_DONE(j)) {
-                       struct panfrost_job *job;
+               for (i = 0; i < ARRAY_SIZE(done[0]) && done[j][i]; i++) {
+                       /* Set ->jc to 0 to avoid re-submitting an already
+                        * finished job (can happen when we receive the DONE
+                        * interrupt while doing a GPU reset).
+                        */
+                       done[j][i]->jc = 0;
+                       panfrost_mmu_as_put(pfdev, done[j][i]->file_priv->mmu);
+                       panfrost_devfreq_record_idle(&pfdev->pfdevfreq);
 
-                       spin_lock(&pfdev->js->job_lock);
-                       job = pfdev->jobs[j];
-                       /* Only NULL if job timeout occurred */
-                       if (job) {
-                               pfdev->jobs[j] = NULL;
-
-                               panfrost_mmu_as_put(pfdev, job->file_priv->mmu);
-                               panfrost_devfreq_record_idle(&pfdev->pfdevfreq);
-
-                               dma_fence_signal_locked(job->done_fence);
-                               pm_runtime_put_autosuspend(pfdev->dev);
-                       }
-                       spin_unlock(&pfdev->js->job_lock);
+                       dma_fence_signal_locked(done[j][i]->done_fence);
+                       pm_runtime_put_autosuspend(pfdev->dev);
                }
+       }
 
-               status &= ~mask;
+       for (j = 0; j < NUM_JOB_SLOTS; j++) {
+               if (!(js_events & MK_JS_MASK(j)))
+                       continue;
+
+               if (!failed[j] || !pfdev->jobs[j][0])
+                       continue;
+
+               if (pfdev->jobs[j][0]->jc == 0) {
+                       /* The job was cancelled, signal the fence now */
+                       struct panfrost_job *canceled = 
panfrost_dequeue_job(pfdev, j);
+
+                       panfrost_mmu_as_put(pfdev, canceled->file_priv->mmu);
+                       panfrost_devfreq_record_idle(&pfdev->pfdevfreq);
+
+                       dma_fence_set_error(canceled->done_fence, -ECANCELED);
+                       dma_fence_signal_locked(canceled->done_fence);
+                       pm_runtime_put_autosuspend(pfdev->dev);
+               } else if (!atomic_read(&pfdev->reset.pending)) {
+                       /* Resume the job we stopped if no reset is pending */
+                       job_write(pfdev, JS_COMMAND_NEXT(j), JS_COMMAND_START);
+               }
        }
 }
 
@@ -583,12 +690,36 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void 
*data)
        return IRQ_WAKE_THREAD;
 }
 
+static u32 panfrost_active_slots(struct panfrost_device *pfdev,
+                                u32 *js_state_mask, u32 js_state)
+{
+       u32 rawstat;
+
+       if (!(js_state & *js_state_mask))
+               return 0;
+
+       rawstat = job_read(pfdev, JOB_INT_RAWSTAT);
+       if (rawstat) {
+               unsigned int i;
+
+               for (i = 0; i < NUM_JOB_SLOTS; i++) {
+                       if (rawstat & MK_JS_MASK(i))
+                               *js_state_mask &= ~MK_JS_MASK(i);
+               }
+       }
+
+       return js_state & *js_state_mask;
+}
+
 static void panfrost_reset(struct work_struct *work)
 {
        struct panfrost_device *pfdev = container_of(work,
                                                     struct panfrost_device,
                                                     reset.work);
+       u32 js_state, js_state_mask = 0xffffffff;
        unsigned int i;
+       bool cookie;
+       int ret;
 
        for (i = 0; i < NUM_JOB_SLOTS; i++) {
                /*
@@ -612,21 +743,43 @@ static void panfrost_reset(struct work_struct *work)
                panfrost_scheduler_stop(&pfdev->js->queue[i], NULL);
        }
 
-       /* All timers have been stopped, we can safely reset the pending state. 
*/
-       atomic_set(&pfdev->reset.pending, 0);
+       /* Mask job interrupts and make sure all interrupt handlers have
+        * returned. We'll call the job interrupt handler manually, after
+        * issuing soft-stops.
+        */
+       job_write(pfdev, JOB_INT_MASK, 0);
+       synchronize_irq(pfdev->js->irq);
 
-       spin_lock(&pfdev->js->job_lock);
        for (i = 0; i < NUM_JOB_SLOTS; i++) {
-               if (pfdev->jobs[i]) {
-                       pm_runtime_put_noidle(pfdev->dev);
-                       panfrost_devfreq_record_idle(&pfdev->pfdevfreq);
-                       pfdev->jobs[i] = NULL;
-               }
+               /* Cancel the next job and soft-stop the running job. */
+               job_write(pfdev, JS_COMMAND_NEXT(i), JS_COMMAND_NOP);
+               job_write(pfdev, JS_COMMAND(i), JS_COMMAND_SOFT_STOP);
        }
-       spin_unlock(&pfdev->js->job_lock);
 
+       /* Wait at most 10ms for soft-stops to complete */
+       job_write(pfdev, JOB_INT_MASK, 0);
+       ret = readl_poll_timeout(pfdev->iomem + JOB_INT_JS_STATE, js_state,
+                                !panfrost_active_slots(pfdev, &js_state_mask, 
js_state),
+                                10, 10000);
+
+       if (ret)
+               dev_err(pfdev->dev, "Soft-stop failed (active_mask=%x)\n", 
js_state);
+
+       /* Handle the remaining interrupts before we reset. */
+       cookie = dma_fence_begin_signalling();
+       panfrost_job_irq_handler_thread(pfdev->js->irq, pfdev);
+       dma_fence_end_signalling(cookie);
+
+       /* Proceed with reset now. */
        panfrost_device_reset(pfdev);
 
+       /* Reset is done, we can clear the pending flag. */
+       atomic_set(&pfdev->reset.pending, 0);
+
+       /* Now resubmit jobs that were previously queued but didn't have a
+        * chance to finish.
+        */
+       memset(pfdev->jobs, 0, sizeof(pfdev->jobs));
        for (i = 0; i < NUM_JOB_SLOTS; i++)
                panfrost_scheduler_start(&pfdev->js->queue[i]);
 }
@@ -634,7 +787,7 @@ static void panfrost_reset(struct work_struct *work)
 int panfrost_job_init(struct panfrost_device *pfdev)
 {
        struct panfrost_job_slot *js;
-       int ret, j, irq;
+       int ret, j;
 
        INIT_WORK(&pfdev->reset.work, panfrost_reset);
 
@@ -644,11 +797,11 @@ int panfrost_job_init(struct panfrost_device *pfdev)
 
        spin_lock_init(&js->job_lock);
 
-       irq = platform_get_irq_byname(to_platform_device(pfdev->dev), "job");
-       if (irq <= 0)
+       js->irq = platform_get_irq_byname(to_platform_device(pfdev->dev), 
"job");
+       if (js->irq <= 0)
                return -ENODEV;
 
-       ret = devm_request_threaded_irq(pfdev->dev, irq,
+       ret = devm_request_threaded_irq(pfdev->dev, js->irq,
                                        panfrost_job_irq_handler,
                                        panfrost_job_irq_handler_thread,
                                        IRQF_SHARED, KBUILD_MODNAME "-job",
@@ -665,7 +818,7 @@ int panfrost_job_init(struct panfrost_device *pfdev)
 
                ret = drm_sched_init(&js->queue[j].sched,
                                     &panfrost_sched_ops,
-                                    1, 0, msecs_to_jiffies(JOB_TIMEOUT_MS),
+                                    2, 0, msecs_to_jiffies(JOB_TIMEOUT_MS),
                                     NULL, "pan_js");
                if (ret) {
                        dev_err(pfdev->dev, "Failed to create scheduler: %d.", 
ret);
@@ -728,12 +881,30 @@ void panfrost_job_close(struct panfrost_file_priv 
*panfrost_priv)
        spin_lock(&pfdev->js->job_lock);
        for (i = 0; i < NUM_JOB_SLOTS; i++) {
                struct drm_sched_entity *entity = 
&panfrost_priv->sched_entity[i];
-               struct panfrost_job *job = pfdev->jobs[i];
+               int j;
 
-               if (!job || job->base.entity != entity)
-                       continue;
+               for (j = ARRAY_SIZE(pfdev->jobs[0]) - 1; j >= 0; j--) {
+                       struct panfrost_job *job = pfdev->jobs[i][j];
+                       u32 cmd;
 
-               job_write(pfdev, JS_COMMAND(i), JS_COMMAND_HARD_STOP);
+                       if (!job || job->base.entity != entity)
+                               continue;
+
+                       if (j == 1) {
+                               /* Try to cancel the job before it starts */
+                               job_write(pfdev, JS_COMMAND_NEXT(i), 
JS_COMMAND_NOP);
+                               /* Reset the job head so it doesn't get 
restarted if
+                                * the job in the first slot failed.
+                                */
+                               job->jc = 0;
+                       }
+
+                       cmd = panfrost_get_job_chain_flag(job) ?
+                             JS_COMMAND_HARD_STOP_1 :
+                             JS_COMMAND_HARD_STOP_0;
+
+                       job_write(pfdev, JS_COMMAND(i), cmd);
+               }
        }
        spin_unlock(&pfdev->js->job_lock);
 }
-- 
2.31.1

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