[PATCH v5 06/18] drm/imagination: Mask GPU IRQs in threaded handler

[Matt Coster <matt.coster@imgtec.com>]

From: Alessio Belle <alessio.belle@imgtec.com>

Pass IRQF_ONESHOT flag to request_threaded_irq(), so that interrupts will
be masked by the kernel until the end of the threaded IRQ handler. Since
the calls to pvr_fw_irq_enable() and pvr_fw_irq_disable() are now
redundant, remove them.

Interrupts to the host from the soon-to-be-added RISC-V firmware
processors cannot be masked in hardware. This change allows us to continue
using the threaded handler in GPUs with a RISC-V firmware.

For simplicity, the same approach is taken for all firmware processors.

Signed-off-by: Alessio Belle <alessio.belle@imgtec.com>
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
---
Changes in v5:
- None
- Link to v4: https://lore.kernel.org/r/20250320-sets-bxs-4-64-patch-v1-v4-6-d987cf4ca439@imgtec.com
Changes in v4:
- None
- Link to v3: https://lore.kernel.org/r/20250310-sets-bxs-4-64-patch-v1-v3-6-143b3dbef02f@imgtec.com
Changes in v3:
- Added
---
 drivers/gpu/drm/imagination/pvr_device.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/imagination/pvr_device.c b/drivers/gpu/drm/imagination/pvr_device.c
index 1704c0268589bdeb65fa6535f9ec63182b0a3e94..b6ce936f07c8bb26d240e50b72a1d991dbe4b045 100644
--- a/drivers/gpu/drm/imagination/pvr_device.c
+++ b/drivers/gpu/drm/imagination/pvr_device.c
@@ -169,8 +169,6 @@ static irqreturn_t pvr_device_irq_thread_handler(int irq, void *data)
 		ret = IRQ_HANDLED;
 	}
 
-	/* Unmask FW irqs before returning, so new interrupts can be received. */
-	pvr_fw_irq_enable(pvr_dev);
 	return ret;
 }
 
@@ -181,10 +179,6 @@ static irqreturn_t pvr_device_irq_handler(int irq, void *data)
 	if (!pvr_fw_irq_pending(pvr_dev))
 		return IRQ_NONE; /* Spurious IRQ - ignore. */
 
-	/* Mask the FW interrupts before waking up the thread. Will be unmasked
-	 * when the thread handler is done processing events.
-	 */
-	pvr_fw_irq_disable(pvr_dev);
 	return IRQ_WAKE_THREAD;
 }
 
@@ -213,9 +207,13 @@ pvr_device_irq_init(struct pvr_device *pvr_dev)
 	pvr_fw_irq_clear(pvr_dev);
 	pvr_fw_irq_enable(pvr_dev);
 
+	/*
+	 * The ONESHOT flag ensures IRQs are masked while the thread handler is
+	 * running.
+	 */
 	return request_threaded_irq(pvr_dev->irq, pvr_device_irq_handler,
 				    pvr_device_irq_thread_handler,
-				    IRQF_SHARED, "gpu", pvr_dev);
+				    IRQF_SHARED | IRQF_ONESHOT, "gpu", pvr_dev);
 }
 
 /**

-- 
2.49.0