Commit 157ad4cc authored by AngeloGioacchino Del Regno's avatar AngeloGioacchino Del Regno Committed by Boris Brezillon
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drm/panfrost: Synchronize and disable interrupts before powering off 



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 requires to add a mechanism to synchronize the
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 an `is_suspended` bitmap which is used to address the
possible corner case of unintentional IRQ unmasking because of ISR
execution after a call to synchronize_irq().

At resume, clear each is_suspended bit in the reset path of JOB/MMU
to allow unmasking the interrupts.

Signed-off-by: default avatarAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231204114215.54575-4-angelogioacchino.delregno@collabora.com
parent b98e9a84

drivers/gpu/drm/panfrost/panfrost_device.c

+3 −0
Original line number Diff line number Diff line
@@ -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;

drivers/gpu/drm/panfrost/panfrost_device.h

+8 −0
Original line number Diff line number Diff line
@@ -25,6 +25,13 @@ struct panfrost_perfcnt; 
#define NUM_JOB_SLOTS 3

#define MAX_PM_DOMAINS 5



enum panfrost_drv_comp_bits {

	PANFROST_COMP_BIT_GPU,

	PANFROST_COMP_BIT_JOB,

	PANFROST_COMP_BIT_MMU,

	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 +116,7 @@ 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;

drivers/gpu/drm/panfrost/panfrost_gpu.c

+16 −2
Original line number Diff line number Diff line
@@ -22,9 +22,13 @@ 
static irqreturn_t panfrost_gpu_irq_handler(int irq, void *data)

{

	struct panfrost_device *pfdev = data;

	u32 state = gpu_read(pfdev, GPU_INT_STAT);

	u32 fault_status = gpu_read(pfdev, GPU_FAULT_STATUS);

	u32 fault_status, state;



	if (test_bit(PANFROST_COMP_BIT_GPU, pfdev->is_suspended))

		return IRQ_NONE;



	fault_status = gpu_read(pfdev, GPU_FAULT_STATUS);

	state = gpu_read(pfdev, GPU_INT_STAT);

	if (!state)

		return IRQ_NONE;
@@ -61,6 +65,8 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev) 
	gpu_write(pfdev, GPU_INT_MASK, 0);

	gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_RESET_COMPLETED);



	clear_bit(PANFROST_COMP_BIT_GPU, pfdev->is_suspended);



	gpu_write(pfdev, GPU_CMD, GPU_CMD_SOFT_RESET);

	ret = readl_relaxed_poll_timeout(pfdev->iomem + GPU_INT_RAWSTAT,

		val, val & GPU_IRQ_RESET_COMPLETED, 10, 10000);
@@ -452,6 +458,14 @@ 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);



	gpu_write(pfdev, GPU_INT_MASK, 0);

	synchronize_irq(pfdev->gpu_irq);

}



int panfrost_gpu_init(struct panfrost_device *pfdev)

{

	int err;

drivers/gpu/drm/panfrost/panfrost_gpu.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

drivers/gpu/drm/panfrost/panfrost_job.c

+22 −4
Original line number Diff line number Diff line
@@ -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)
@@ -792,17 +802,25 @@ static irqreturn_t panfrost_job_irq_handler_thread(int irq, void *data) 
	struct panfrost_device *pfdev = data;



	panfrost_job_handle_irqs(pfdev);



	/* 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));



	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);

	u32 status;



	if (test_bit(PANFROST_COMP_BIT_JOB, pfdev->is_suspended))

		return IRQ_NONE;



	status = job_read(pfdev, JOB_INT_STAT);

	if (!status)

		return IRQ_NONE;