[PATCH 0/3] HID: Intel-thc-hid: Refine error recovery flow

[PATCH 0/3] HID: Intel-thc-hid: Refine error recovery flow

[Even Xu]

This series refines the fatal error recovery flow for the Intel THC
(Touch Host Controller) subsystem, covering both the QuickI2C and
QuickSPI drivers.

Currently, when a fatal DMA error is detected in the IRQ thread handler,
the recovery is performed inline: the interrupt handler calls
try_recover() directly, which unconfigures and reconfigures the DMA
engine.

This approach has several problems:
1. Recovery runs in the IRQ thread context, which is not ideal for
   potentially slow reset operations.
2. The interrupt is re-enabled before recovery completes, risking an
   interrupt storm if DMA errors persist.
3. The DMA reset logic is open-coded in each protocol driver, leading
   to duplication and divergence over time.

This patch series addresses all of the above:

By adding a new thc_rxdma_reset() API to the THC core layer, QuickI2C
and QuickSPI drivers can call it respectively to refine the recovery
callback.

The synchronous try_recover() call in the IRQ thread is replaced with
schedule_work(), deferring recovery to a workqueue.  Within the work
function:
- The interrupt line is disabled before any DMA manipulation.
- thc_rxdma_reset() is used instead of the open-coded sequence.
- On failure the device is marked DISABLED and the interrupt remains
  off, preventing an interrupt storm.

Even Xu (3):
  HID: Intel-thc-hid: Intel-thc: Add API to reset read DMA
  HID: Intel-thc-hid: Intel-quicki2c: Refine recover callback
  HID: Intel-thc-hid: Intel-quickspi: Refine recover callback

 .../intel-quicki2c/pci-quicki2c.c             | 31 +++++++---------
 .../intel-quicki2c/quicki2c-dev.h             |  2 +
 .../intel-quickspi/pci-quickspi.c             | 37 +++++++------------
 .../intel-quickspi/quickspi-dev.h             |  2 +
 .../intel-thc-hid/intel-thc/intel-thc-dma.c   | 37 +++++++++++++++++++
 .../intel-thc-hid/intel-thc/intel-thc-dma.h   |  1 +
 6 files changed, 68 insertions(+), 42 deletions(-)

-- 
2.43.0

[PATCH 1/3] HID: Intel-thc-hid: Intel-thc: Add API to reset read DMA

[Even Xu]

Add a helper function thc_rxdam_reset() to do read DMA reset, it can be
called when fatal DMA error happens.

Signed-off-by: Even Xu <even.xu@intel.com>
---
 .../intel-thc-hid/intel-thc/intel-thc-dma.c   | 37 +++++++++++++++++++
 .../intel-thc-hid/intel-thc/intel-thc-dma.h   |  1 +
 2 files changed, 38 insertions(+)

diff --git a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c
index 6ee675e0a738..d771c85dff28 100644
--- a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c
+++ b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.c
@@ -532,6 +532,43 @@ void thc_dma_unconfigure(struct thc_device *dev)
 }
 EXPORT_SYMBOL_NS_GPL(thc_dma_unconfigure, "INTEL_THC");
 
+/**
+ * thc_rxdma_reset - Reset all read DMA engines
+ *
+ * @dev: The pointer of THC private device context
+ *
+ * This is a helper function to reset RxDMA configure. It's typically used
+ * for RxDMA recovery when fatal error happens.
+ */
+int thc_rxdma_reset(struct thc_device *dev)
+{
+	int ret;
+
+	if (mutex_lock_interruptible(&dev->thc_bus_lock))
+		return -EINTR;
+
+	ret = thc_interrupt_quiesce(dev, true);
+	if (ret) {
+		dev_err_once(dev->dev, "Quiesce interrupt failed during RxDMA reset\n");
+		goto end;
+	}
+
+	thc_dma_unconfigure(dev);
+
+	ret = thc_dma_configure(dev);
+	if (ret) {
+		dev_err_once(dev->dev, "Re-config DMA failed during RxDMA reset\n");
+		goto end;
+	}
+
+	thc_interrupt_quiesce(dev, false);
+
+end:
+	mutex_unlock(&dev->thc_bus_lock);
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(thc_rxdma_reset, "INTEL_THC");
+
 static int thc_wait_for_dma_pause(struct thc_device *dev, enum thc_dma_channel channel)
 {
 	u32 ctrl_reg, sts_reg, sts;
diff --git a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h
index 541d33995baf..715423453a9d 100644
--- a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h
+++ b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dma.h
@@ -145,6 +145,7 @@ int  thc_dma_allocate(struct thc_device *dev);
 int  thc_dma_configure(struct thc_device *dev);
 void thc_dma_unconfigure(struct thc_device *dev);
 void thc_dma_release(struct thc_device *dev);
+int  thc_rxdma_reset(struct thc_device *dev);
 int  thc_rxdma_read(struct thc_device *dev, enum thc_dma_channel dma_channel,
 		    void *read_buff, size_t *read_len, int *read_finished);
 int  thc_swdma_read(struct thc_device *dev, void *write_buff, size_t write_len,
-- 
2.43.0

[PATCH 2/3] HID: Intel-thc-hid: Intel-quicki2c: Refine recover callback

[Even Xu]

Refine recover flow:
1. Use workqueue to handle recover flow instead of processing in irq
   handler.
2. Call thc_rxdma_reset() API to simplify the recover operation.
3. Disable interrupt during whole recover flow.
4. If recover fails, disable interrupt to avoid interrupt storm.

Signed-off-by: Even Xu <even.xu@intel.com>
---
 .../intel-quicki2c/pci-quicki2c.c             | 31 ++++++++-----------
 .../intel-quicki2c/quicki2c-dev.h             |  2 ++
 2 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/drivers/hid/intel-thc-hid/intel-quicki2c/pci-quicki2c.c b/drivers/hid/intel-thc-hid/intel-quicki2c/pci-quicki2c.c
index 46d3e9a01999..411d7a0ab90e 100644
--- a/drivers/hid/intel-thc-hid/intel-quicki2c/pci-quicki2c.c
+++ b/drivers/hid/intel-thc-hid/intel-quicki2c/pci-quicki2c.c
@@ -245,28 +245,23 @@ static irqreturn_t quicki2c_irq_quick_handler(int irq, void *dev_id)
 }
 
 /**
- * try_recover - Try to recovery THC and Device
- * @qcdev: Pointer to quicki2c_device structure
+ * try_recover - Recover callback to recover THC
+ * @work: pointer to work_struct
  *
  * This function is an error handler, called when fatal error happens.
- * It try to reset touch device and re-configure THC to recovery
- * communication between touch device and THC.
- *
- * Return: 0 if successful or error code on failure
+ * It try to reset Touch Device and re-configure THC to recover
+ * transferring between Device and THC.
  */
-static int try_recover(struct quicki2c_device *qcdev)
+static void try_recover(struct work_struct *work)
 {
-	int ret;
+	struct quicki2c_device *qcdev = container_of(work, struct quicki2c_device, recover_work);
 
-	thc_dma_unconfigure(qcdev->thc_hw);
-
-	ret = thc_dma_configure(qcdev->thc_hw);
-	if (ret) {
-		dev_err(qcdev->dev, "Reconfig DMA failed\n");
-		return ret;
-	}
+	thc_interrupt_enable(qcdev->thc_hw, false);
 
-	return 0;
+	if (thc_rxdma_reset(qcdev->thc_hw))
+		qcdev->state = QUICKI2C_DISABLED;
+	else
+		thc_interrupt_enable(qcdev->thc_hw, true);
 }
 
 static int handle_input_report(struct quicki2c_device *qcdev)
@@ -346,8 +341,7 @@ static irqreturn_t quicki2c_irq_thread_handler(int irq, void *dev_id)
 	thc_interrupt_enable(qcdev->thc_hw, true);
 
 	if (err_recover)
-		if (try_recover(qcdev))
-			qcdev->state = QUICKI2C_DISABLED;
+		schedule_work(&qcdev->recover_work);
 
 	pm_runtime_put_autosuspend(qcdev->dev);
 
@@ -386,6 +380,7 @@ static struct quicki2c_device *quicki2c_dev_init(struct pci_dev *pdev, void __io
 	qcdev->ddata = ddata;
 
 	init_waitqueue_head(&qcdev->reset_ack_wq);
+	INIT_WORK(&qcdev->recover_work, try_recover);
 
 	/* THC hardware init */
 	qcdev->thc_hw = thc_dev_init(qcdev->dev, qcdev->mem_addr);
diff --git a/drivers/hid/intel-thc-hid/intel-quicki2c/quicki2c-dev.h b/drivers/hid/intel-thc-hid/intel-quicki2c/quicki2c-dev.h
index 61dbdece59a1..aedf85291e60 100644
--- a/drivers/hid/intel-thc-hid/intel-quicki2c/quicki2c-dev.h
+++ b/drivers/hid/intel-thc-hid/intel-quicki2c/quicki2c-dev.h
@@ -222,6 +222,8 @@ struct quicki2c_device {
 	wait_queue_head_t reset_ack_wq;
 	bool reset_ack;
 
+	struct work_struct recover_work;
+
 	u32 i2c_max_frame_size_enable;
 	u32 i2c_max_frame_size;
 	u32 i2c_int_delay_enable;
-- 
2.43.0

[PATCH 3/3] HID: Intel-thc-hid: Intel-quickspi: Refine recover callback

[Even Xu]

Refine recover flow:
1. Use workqueue to handle recover flow instead of processing in irq
   handler.
2. Call thc_rxdma_reset() API to simplify the recover operation.
3. Disable interrupt during whole recover flow.
4. If recover fails, disable interrupt to avoid interrupt storm.

Signed-off-by: Even Xu <even.xu@intel.com>
---
 .../intel-quickspi/pci-quickspi.c             | 37 +++++++------------
 .../intel-quickspi/quickspi-dev.h             |  2 +
 2 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c b/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
index f669235f1883..1e63b183b3b1 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
@@ -252,34 +252,23 @@ static irqreturn_t quickspi_irq_quick_handler(int irq, void *dev_id)
 }
 
 /**
- * try_recover - Try to recovery THC and Device
- * @qsdev: pointer to quickspi device
+ * try_recover - Recover callback to recover THC
+ * @work: pointer to work_struct
  *
- * This function is a error handler, called when fatal error happens.
- * It try to reset Touch Device and re-configure THC to recovery
+ * This function is an error handler, called when fatal error happens.
+ * It try to reset Touch Device and re-configure THC to recover
  * transferring between Device and THC.
- *
- * Return: 0 if successful or error code on failed.
  */
-static int try_recover(struct quickspi_device *qsdev)
+static void try_recover(struct work_struct *work)
 {
-	int ret;
+	struct quickspi_device *qsdev = container_of(work, struct quickspi_device, recover_work);
 
-	ret = reset_tic(qsdev);
-	if (ret) {
-		dev_err(qsdev->dev, "Reset touch device failed, ret = %d\n", ret);
-		return ret;
-	}
-
-	thc_dma_unconfigure(qsdev->thc_hw);
-
-	ret = thc_dma_configure(qsdev->thc_hw);
-	if (ret) {
-		dev_err(qsdev->dev, "Re-configure THC DMA failed, ret = %d\n", ret);
-		return ret;
-	}
+	thc_interrupt_enable(qsdev->thc_hw, false);
 
-	return 0;
+	if (thc_rxdma_reset(qsdev->thc_hw))
+		qsdev->state = QUICKSPI_DISABLED;
+	else
+		thc_interrupt_enable(qsdev->thc_hw, true);
 }
 
 /**
@@ -340,8 +329,7 @@ static irqreturn_t quickspi_irq_thread_handler(int irq, void *dev_id)
 	thc_interrupt_enable(qsdev->thc_hw, true);
 
 	if (err_recover)
-		if (try_recover(qsdev))
-			qsdev->state = QUICKSPI_DISABLED;
+		schedule_work(&qsdev->recover_work);
 
 	pm_runtime_put_autosuspend(qsdev->dev);
 
@@ -385,6 +373,7 @@ static struct quickspi_device *quickspi_dev_init(struct pci_dev *pdev, void __io
 	init_waitqueue_head(&qsdev->report_desc_got_wq);
 	init_waitqueue_head(&qsdev->get_report_cmpl_wq);
 	init_waitqueue_head(&qsdev->set_report_cmpl_wq);
+	INIT_WORK(&qsdev->recover_work, try_recover);
 
 	/* thc hw init */
 	qsdev->thc_hw = thc_dev_init(qsdev->dev, qsdev->mem_addr);
diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
index bf5e18f5a5f4..b0c1219866a4 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
@@ -173,6 +173,8 @@ struct quickspi_device {
 
 	wait_queue_head_t set_report_cmpl_wq;
 	bool set_report_cmpl;
+
+	struct work_struct recover_work;
 };
 
 #endif /* _QUICKSPI_DEV_H_ */
-- 
2.43.0