Re: [PATCH v3 3/3] drm/panfrost: Synchronize and disable interrupts before powering off
From: AngeloGioacchino Del Regno
Date: Mon Dec 04 2023 - 06:20:38 EST
Il 01/12/23 12:14, Boris Brezillon ha scritto:
On Fri, 1 Dec 2023 11:40:27 +0100
AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
wrote:
To make sure that we don't unintentionally perform any unclocked and/or
unpowered R/W operation on GPU registers, before turning off clocks and
regulators we must make sure that no GPU, JOB or MMU ISR execution is
pending: doing that required to add a mechanism to synchronize the
^ requires the addition of a mechanism...
interrupts on suspend.
Add functions panfrost_{gpu,job,mmu}_suspend_irq() which will perform
interrupts masking and ISR execution synchronization, and then call
those in the panfrost_device_runtime_suspend() handler in the exact
sequence of job (may require mmu!) -> mmu -> gpu.
As a side note, JOB and MMU suspend_irq functions needed some special
treatment: as their interrupt handlers will unmask interrupts, it was
necessary to add a bitmap for `is_suspended` which is used to address
to add an `is_suspended` bitmap which is used...
the possible corner case of unintentional IRQ unmasking because of ISR
execution after a call to synchronize_irq().
Also fixes the case where the interrupt handler is called when the
device is suspended because the IRQ line is shared with another device.
No need to update the commit message for that though.
At resume, clear each is_suspended bit in the reset path of JOB/MMU
to allow unmasking the interrupts.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
---
drivers/gpu/drm/panfrost/panfrost_device.c | 3 +++
drivers/gpu/drm/panfrost/panfrost_device.h | 7 +++++++
drivers/gpu/drm/panfrost/panfrost_gpu.c | 6 ++++++
drivers/gpu/drm/panfrost/panfrost_gpu.h | 1 +
drivers/gpu/drm/panfrost/panfrost_job.c | 20 +++++++++++++++++---
drivers/gpu/drm/panfrost/panfrost_job.h | 1 +
drivers/gpu/drm/panfrost/panfrost_mmu.c | 19 ++++++++++++++++---
drivers/gpu/drm/panfrost/panfrost_mmu.h | 1 +
8 files changed, 52 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index c90ad5ee34e7..a45e4addcc19 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -421,6 +421,9 @@ static int panfrost_device_runtime_suspend(struct device *dev)
return -EBUSY;
panfrost_devfreq_suspend(pfdev);
+ panfrost_job_suspend_irq(pfdev);
+ panfrost_mmu_suspend_irq(pfdev);
+ panfrost_gpu_suspend_irq(pfdev);
panfrost_gpu_power_off(pfdev);
return 0;
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index 54a8aad54259..5c24f01f8904 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -25,6 +25,12 @@ struct panfrost_perfcnt;
#define NUM_JOB_SLOTS 3
#define MAX_PM_DOMAINS 5
+enum panfrost_drv_comp_bits {
+ PANFROST_COMP_BIT_MMU,
+ PANFROST_COMP_BIT_JOB,
I think we need one for the GPU interrupt too, for the
irq-line-is-shared-with-another-device thing I was mentioning.
Yes, I've also reordered the entries by name for v4.
+ PANFROST_COMP_BIT_MAX
+};
+
/**
* enum panfrost_gpu_pm - Supported kernel power management features
* @GPU_PM_CLK_DIS: Allow disabling clocks during system suspend
@@ -109,6 +115,7 @@ struct panfrost_device {
struct panfrost_features features;
const struct panfrost_compatible *comp;
+ DECLARE_BITMAP(is_suspended, PANFROST_COMP_BIT_MAX);
spinlock_t as_lock;
unsigned long as_in_use_mask;
diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index 7adc4441fa14..3a6a4fe7aca1 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -452,6 +452,12 @@ void panfrost_gpu_power_off(struct panfrost_device *pfdev)
dev_err(pfdev->dev, "l2 power transition timeout");
}
+void panfrost_gpu_suspend_irq(struct panfrost_device *pfdev)
+{
set_bit(PANFROST_COMP_BIT_GPU, pfdev->is_suspended);
here, and an extra check in panfrost_gpu_irq_handler() to bail out
before the register accesses if PANFROST_COMP_BIT_GPU is set.
Right.
+ gpu_write(pfdev, GPU_INT_MASK, 0);
+ synchronize_irq(pfdev->gpu_irq);
+}
+
int panfrost_gpu_init(struct panfrost_device *pfdev)
{
int err;
diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.h b/drivers/gpu/drm/panfrost/panfrost_gpu.h
index 876fdad9f721..d841b86504ea 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.h
@@ -15,6 +15,7 @@ u32 panfrost_gpu_get_latest_flush_id(struct panfrost_device *pfdev);
int panfrost_gpu_soft_reset(struct panfrost_device *pfdev);
void panfrost_gpu_power_on(struct panfrost_device *pfdev);
void panfrost_gpu_power_off(struct panfrost_device *pfdev);
+void panfrost_gpu_suspend_irq(struct panfrost_device *pfdev);
void panfrost_cycle_counter_get(struct panfrost_device *pfdev);
void panfrost_cycle_counter_put(struct panfrost_device *pfdev);
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index f9446e197428..7600e7741211 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -405,6 +405,8 @@ void panfrost_job_enable_interrupts(struct panfrost_device *pfdev)
int j;
u32 irq_mask = 0;
+ clear_bit(PANFROST_COMP_BIT_JOB, pfdev->is_suspended);
+
for (j = 0; j < NUM_JOB_SLOTS; j++) {
irq_mask |= MK_JS_MASK(j);
}
@@ -413,6 +415,14 @@ void panfrost_job_enable_interrupts(struct panfrost_device *pfdev)
job_write(pfdev, JOB_INT_MASK, irq_mask);
}
+void panfrost_job_suspend_irq(struct panfrost_device *pfdev)
+{
+ set_bit(PANFROST_COMP_BIT_JOB, pfdev->is_suspended);
+
+ job_write(pfdev, JOB_INT_MASK, 0);
+ synchronize_irq(pfdev->js->irq);
+}
+
static void panfrost_job_handle_err(struct panfrost_device *pfdev,
struct panfrost_job *job,
unsigned int js)
@@ -792,9 +802,13 @@ static irqreturn_t panfrost_job_irq_handler_thread(int irq, void *data)
struct panfrost_device *pfdev = data;
panfrost_job_handle_irqs(pfdev);
- job_write(pfdev, JOB_INT_MASK,
- GENMASK(16 + NUM_JOB_SLOTS - 1, 16) |
- GENMASK(NUM_JOB_SLOTS - 1, 0));
+
+ /* Enable interrupts only if we're not about to get suspended */
+ if (!test_bit(PANFROST_COMP_BIT_JOB, pfdev->is_suspended))
+ job_write(pfdev, JOB_INT_MASK,
+ GENMASK(16 + NUM_JOB_SLOTS - 1, 16) |
+ GENMASK(NUM_JOB_SLOTS - 1, 0));
+
Missing if (test_bit(PANFROST_COMP_BIT_JOB, pfdev->is_suspended)) in
panfrost_job_irq_handler(), to make sure you don't access the registers
if the GPU is suspended.
Ok.
Cheers,
Angelo