[PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Sean Anderson]

This series cleans up the zyqnmp_dp IRQ and locking situation. Once
that's done, it adds debugfs support. The intent is to enable compliance
testing or to help debug signal-integrity issues.

Previously, I discussed converting the HPD work(s) to a threaded IRQ. I
did not end up doing that for this series since the steps would be

- Add locking
- Move link retraining to a work function
- Harden the IRQ
- Merge the works into a threaded IRQ (omitted)

Which with the exception of the final step is the same as leaving those
works as-is. Conversion to a threaded IRQ can be done as a follow-up.

Changes in v6:
- Unplug DRM device before removal
- Fix hang upon driver removal
- Rebase onto drm-misc/drm-misc-next

Changes in v5:
- Rebase onto drm-misc/drm-misc-next

Changes in v4:
- Rebase onto drm/drm-next

Changes in v3:
- Convert to a hard IRQ
- Use AUX IRQs instead of polling
- Take dp->lock in zynqmp_dp_hpd_work_func

Changes in v2:
- Split off the HPD IRQ work into another commit
- Expand the commit message
- Document hpd_irq_work
- Document debugfs files
- Add ignore_aux_errors and ignore_hpd debugfs files to replace earlier
  implicit functionality
- Attempt to fix unreproducable, spurious build warning
- Drop "Optionally ignore DPCD errors" in favor of a debugfs file
  directly affecting zynqmp_dp_aux_transfer.

Sean Anderson (8):
  drm: zynqmp_kms: Unplug DRM device before removal
  drm: zynqmp_dp: Add locking
  drm: zynqmp_dp: Don't retrain the link in our IRQ
  drm: zynqmp_dp: Convert to a hard IRQ
  drm: zynqmp_dp: Use AUX IRQs instead of polling
  drm: zynqmp_dp: Split off several helper functions
  drm: zynqmp_dp: Take dp->lock in zynqmp_dp_hpd_work_func
  drm: zynqmp_dp: Add debugfs interface for compliance testing

 Documentation/gpu/drivers.rst     |   1 +
 Documentation/gpu/zynqmp.rst      | 149 ++++++
 MAINTAINERS                       |   1 +
 drivers/gpu/drm/xlnx/zynqmp_dp.c  | 846 ++++++++++++++++++++++++++++--
 drivers/gpu/drm/xlnx/zynqmp_kms.c |   2 +-
 5 files changed, 951 insertions(+), 48 deletions(-)
 create mode 100644 Documentation/gpu/zynqmp.rst

-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 1/8] drm: zynqmp_kms: Unplug DRM device before removal

[Sean Anderson]

Prevent userspace accesses to the DRM device from causing
use-after-frees by unplugging the device before we remove it. This
causes any further userspace accesses to result in an error without
further calls into this driver's internals.

Fixes: d76271d22694 ("drm: xlnx: DRM/KMS driver for Xilinx ZynqMP DisplayPort Subsystem")
Closes: https://lore.kernel.org/dri-devel/4d8f4c9b-2efb-4774-9a37-2f257f79b2c9@linux.dev/
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---
Thanks to Maxime for pointing out the correct function to use here.

Changes in v6:
- New

 drivers/gpu/drm/xlnx/zynqmp_kms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_kms.c b/drivers/gpu/drm/xlnx/zynqmp_kms.c
index bd1368df7870..4556af2faa0f 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_kms.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_kms.c
@@ -536,7 +536,7 @@ void zynqmp_dpsub_drm_cleanup(struct zynqmp_dpsub *dpsub)
 {
 	struct drm_device *drm = &dpsub->drm->dev;
 
-	drm_dev_unregister(drm);
+	drm_dev_unplug(drm);
 	drm_atomic_helper_shutdown(drm);
 	drm_encoder_cleanup(&dpsub->drm->encoder);
 	drm_kms_helper_poll_fini(drm);
-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 2/8] drm: zynqmp_dp: Add locking

[Sean Anderson]

Add some locking to prevent the IRQ/workers/bridge API calls from stepping
on each other's toes. This lock protects:

- Non-atomic registers configuring the link. That is, everything but the
  IRQ registers (since these are accessed in an atomic fashion), and the DP
  AUX registers (since these don't affect the link). We also access AUX
  while holding this lock, so it would be very tricky to support.
- Link configuration. This is effectively everything in zynqmp_dp which
  isn't read-only after probe time. So from next_bridge onward.

This lock is designed to protect configuration changes so we don't have to
do anything tricky. Configuration should never be in the hot path, so I'm
not worried about performance.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

(no changes since v2)

Changes in v2:
- Split off the HPD IRQ work into another commit
- Expand the commit message

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 129beac4c073..abfccd8bb5a7 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -280,6 +280,7 @@ struct zynqmp_dp_config {
  * @dpsub: Display subsystem
  * @iomem: device I/O memory for register access
  * @reset: reset controller
+ * @lock: Mutex protecting this struct and register access (but not AUX)
  * @irq: irq
  * @bridge: DRM bridge for the DP encoder
  * @next_bridge: The downstream bridge
@@ -294,11 +295,16 @@ struct zynqmp_dp_config {
  * @link_config: common link configuration between IP core and sink device
  * @mode: current mode between IP core and sink device
  * @train_set: set of training data
+ *
+ * @lock covers the link configuration in this struct and the device's
+ * registers. It does not cover @aux. It is not strictly required for any of
+ * the members which are only modified at probe/remove time (e.g. @dev).
  */
 struct zynqmp_dp {
 	struct drm_dp_aux aux;
 	struct drm_bridge bridge;
 	struct work_struct hpd_work;
+	struct mutex lock;
 
 	struct drm_bridge *next_bridge;
 	struct device *dev;
@@ -1386,8 +1392,10 @@ zynqmp_dp_bridge_mode_valid(struct drm_bridge *bridge,
 	}
 
 	/* Check with link rate and lane count */
+	mutex_lock(&dp->lock);
 	rate = zynqmp_dp_max_rate(dp->link_config.max_rate,
 				  dp->link_config.max_lanes, dp->config.bpp);
+	mutex_unlock(&dp->lock);
 	if (mode->clock > rate) {
 		dev_dbg(dp->dev, "filtered mode %s for high pixel rate\n",
 			mode->name);
@@ -1414,6 +1422,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 
 	pm_runtime_get_sync(dp->dev);
 
+	mutex_lock(&dp->lock);
 	zynqmp_dp_disp_enable(dp, old_bridge_state);
 
 	/*
@@ -1474,6 +1483,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 	zynqmp_dp_write(dp, ZYNQMP_DP_SOFTWARE_RESET,
 			ZYNQMP_DP_SOFTWARE_RESET_ALL);
 	zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 1);
+	mutex_unlock(&dp->lock);
 }
 
 static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,
@@ -1481,6 +1491,7 @@ static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,
 {
 	struct zynqmp_dp *dp = bridge_to_dp(bridge);
 
+	mutex_lock(&dp->lock);
 	dp->enabled = false;
 	cancel_work(&dp->hpd_work);
 	zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 0);
@@ -1491,6 +1502,7 @@ static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,
 		zynqmp_dp_write(dp, ZYNQMP_DP_TX_AUDIO_CONTROL, 0);
 
 	zynqmp_dp_disp_disable(dp, old_bridge_state);
+	mutex_unlock(&dp->lock);
 
 	pm_runtime_put_sync(dp->dev);
 }
@@ -1533,6 +1545,8 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid
 	u32 state, i;
 	int ret;
 
+	mutex_lock(&dp->lock);
+
 	/*
 	 * This is from heuristic. It takes some delay (ex, 100 ~ 500 msec) to
 	 * get the HPD signal with some monitors.
@@ -1560,11 +1574,13 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid
 					       dp->num_lanes);
 
 		dp->status = connector_status_connected;
+		mutex_unlock(&dp->lock);
 		return connector_status_connected;
 	}
 
 disconnected:
 	dp->status = connector_status_disconnected;
+	mutex_unlock(&dp->lock);
 	return connector_status_disconnected;
 }
 
@@ -1725,6 +1741,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
 	dp->dev = &pdev->dev;
 	dp->dpsub = dpsub;
 	dp->status = connector_status_disconnected;
+	mutex_init(&dp->lock);
 
 	INIT_WORK(&dp->hpd_work, zynqmp_dp_hpd_work_func);
 
@@ -1838,4 +1855,5 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub)
 
 	zynqmp_dp_phy_exit(dp);
 	zynqmp_dp_reset(dp, true);
+	mutex_destroy(&dp->lock);
 }
-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 3/8] drm: zynqmp_dp: Don't retrain the link in our IRQ

[Sean Anderson]

Retraining the link can take a while, and might involve waiting for
DPCD reads/writes to complete. In preparation for unthreading the IRQ
handler, move this into its own work function.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

(no changes since v2)

Changes in v2:
- Document hpd_irq_work
- Split this off from the locking changes

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 45 ++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index abfccd8bb5a7..cec5711c7026 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -289,6 +289,7 @@ struct zynqmp_dp_config {
  * @phy: PHY handles for DP lanes
  * @num_lanes: number of enabled phy lanes
  * @hpd_work: hot plug detection worker
+ * @hpd_irq_work: hot plug detection IRQ worker
  * @status: connection status
  * @enabled: flag to indicate if the device is enabled
  * @dpcd: DP configuration data from currently connected sink device
@@ -304,6 +305,7 @@ struct zynqmp_dp {
 	struct drm_dp_aux aux;
 	struct drm_bridge bridge;
 	struct work_struct hpd_work;
+	struct work_struct hpd_irq_work;
 	struct mutex lock;
 
 	struct drm_bridge *next_bridge;
@@ -1671,6 +1673,29 @@ static void zynqmp_dp_hpd_work_func(struct work_struct *work)
 	drm_bridge_hpd_notify(&dp->bridge, status);
 }
 
+static void zynqmp_dp_hpd_irq_work_func(struct work_struct *work)
+{
+	struct zynqmp_dp *dp = container_of(work, struct zynqmp_dp,
+					    hpd_irq_work);
+	u8 status[DP_LINK_STATUS_SIZE + 2];
+	int err;
+
+	mutex_lock(&dp->lock);
+	err = drm_dp_dpcd_read(&dp->aux, DP_SINK_COUNT, status,
+			       DP_LINK_STATUS_SIZE + 2);
+	if (err < 0) {
+		dev_dbg_ratelimited(dp->dev,
+				    "could not read sink status: %d\n", err);
+	} else {
+		if (status[4] & DP_LINK_STATUS_UPDATED ||
+		    !drm_dp_clock_recovery_ok(&status[2], dp->mode.lane_cnt) ||
+		    !drm_dp_channel_eq_ok(&status[2], dp->mode.lane_cnt)) {
+			zynqmp_dp_train_loop(dp);
+		}
+	}
+	mutex_unlock(&dp->lock);
+}
+
 static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
 {
 	struct zynqmp_dp *dp = (struct zynqmp_dp *)data;
@@ -1702,23 +1727,9 @@ static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
 	if (status & ZYNQMP_DP_INT_HPD_EVENT)
 		schedule_work(&dp->hpd_work);
 
-	if (status & ZYNQMP_DP_INT_HPD_IRQ) {
-		int ret;
-		u8 status[DP_LINK_STATUS_SIZE + 2];
+	if (status & ZYNQMP_DP_INT_HPD_IRQ)
+		schedule_work(&dp->hpd_irq_work);
 
-		ret = drm_dp_dpcd_read(&dp->aux, DP_SINK_COUNT, status,
-				       DP_LINK_STATUS_SIZE + 2);
-		if (ret < 0)
-			goto handled;
-
-		if (status[4] & DP_LINK_STATUS_UPDATED ||
-		    !drm_dp_clock_recovery_ok(&status[2], dp->mode.lane_cnt) ||
-		    !drm_dp_channel_eq_ok(&status[2], dp->mode.lane_cnt)) {
-			zynqmp_dp_train_loop(dp);
-		}
-	}
-
-handled:
 	return IRQ_HANDLED;
 }
 
@@ -1744,6 +1755,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
 	mutex_init(&dp->lock);
 
 	INIT_WORK(&dp->hpd_work, zynqmp_dp_hpd_work_func);
+	INIT_WORK(&dp->hpd_irq_work, zynqmp_dp_hpd_irq_work_func);
 
 	/* Acquire all resources (IOMEM, IRQ and PHYs). */
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dp");
@@ -1848,6 +1860,7 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub)
 	zynqmp_dp_write(dp, ZYNQMP_DP_INT_DS, ZYNQMP_DP_INT_ALL);
 	disable_irq(dp->irq);
 
+	cancel_work_sync(&dp->hpd_irq_work);
 	cancel_work_sync(&dp->hpd_work);
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_TRANSMITTER_ENABLE, 0);
-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 4/8] drm: zynqmp_dp: Convert to a hard IRQ

[Sean Anderson]

Now that all of the sleeping work is done outside of the IRQ, we can
convert it to a hard IRQ. Shared IRQs may be triggered even after
calling disable_irq, so use free_irq instead which removes our callback
altogether.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

Changes in v6:
- Fix hang upon driver removal

Changes in v3:
- New

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index cec5711c7026..532e103713b3 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -1831,9 +1831,8 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
 	 * Now that the hardware is initialized and won't generate spurious
 	 * interrupts, request the IRQ.
 	 */
-	ret = devm_request_threaded_irq(dp->dev, dp->irq, NULL,
-					zynqmp_dp_irq_handler, IRQF_ONESHOT,
-					dev_name(dp->dev), dp);
+	ret = devm_request_irq(dp->dev, dp->irq, zynqmp_dp_irq_handler,
+			       IRQF_SHARED, dev_name(dp->dev), dp);
 	if (ret < 0)
 		goto err_phy_exit;
 
@@ -1858,7 +1857,7 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub)
 	struct zynqmp_dp *dp = dpsub->dp;
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_INT_DS, ZYNQMP_DP_INT_ALL);
-	disable_irq(dp->irq);
+	devm_free_irq(dp->dev, dp->irq, dp);
 
 	cancel_work_sync(&dp->hpd_irq_work);
 	cancel_work_sync(&dp->hpd_work);
-- 
2.35.1.1320.gc452695387.dirty

Re: [PATCH v6 4/8] drm: zynqmp_dp: Convert to a hard IRQ

[Tomi Valkeinen]

Hi,

On 09/08/2024 22:35, Sean Anderson wrote:
> Now that all of the sleeping work is done outside of the IRQ, we can
> convert it to a hard IRQ. Shared IRQs may be triggered even after
> calling disable_irq, so use free_irq instead which removes our callback
> altogether.
> 
> Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
> ---
> 
> Changes in v6:
> - Fix hang upon driver removal
> 
> Changes in v3:
> - New
> 
>   drivers/gpu/drm/xlnx/zynqmp_dp.c | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> index cec5711c7026..532e103713b3 100644
> --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
> +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> @@ -1831,9 +1831,8 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
>   	 * Now that the hardware is initialized and won't generate spurious
>   	 * interrupts, request the IRQ.
>   	 */
> -	ret = devm_request_threaded_irq(dp->dev, dp->irq, NULL,
> -					zynqmp_dp_irq_handler, IRQF_ONESHOT,
> -					dev_name(dp->dev), dp);
> +	ret = devm_request_irq(dp->dev, dp->irq, zynqmp_dp_irq_handler,
> +			       IRQF_SHARED, dev_name(dp->dev), dp);
>   	if (ret < 0)
>   		goto err_phy_exit;
>   
> @@ -1858,7 +1857,7 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub)
>   	struct zynqmp_dp *dp = dpsub->dp;
>   
>   	zynqmp_dp_write(dp, ZYNQMP_DP_INT_DS, ZYNQMP_DP_INT_ALL);
> -	disable_irq(dp->irq);
> +	devm_free_irq(dp->dev, dp->irq, dp);
>   
>   	cancel_work_sync(&dp->hpd_irq_work);
>   	cancel_work_sync(&dp->hpd_work);

Not much point using devm for request irq, I think, as it's manually freed.

Another thing, which I think is not an issue at the moment nor related 
to this series as such, is that we use IRQF_SHARED and 
zynqmp_dp_irq_handler() will read a DP register right away. This means 
that if the DP is runtime suspended and we get an interrupt, the driver 
accesses a register on a suspended IP, which often leads to crash/hang.

Here I think we enable all necessary clocks at probe time, so the DP is 
always enabled and the above is not an issue.

In any case, even with the current devm:

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

  Tomi

[PATCH v6 5/8] drm: zynqmp_dp: Use AUX IRQs instead of polling

[Sean Anderson]

Instead of polling the status register for the AUX status, just enable
the IRQs and signal a completion.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

(no changes since v3)

Changes in v3:
- New

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 35 +++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 532e103713b3..babfa3581014 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -286,6 +286,7 @@ struct zynqmp_dp_config {
  * @next_bridge: The downstream bridge
  * @config: IP core configuration from DTS
  * @aux: aux channel
+ * @aux_done: Completed when we get an AUX reply or timeout
  * @phy: PHY handles for DP lanes
  * @num_lanes: number of enabled phy lanes
  * @hpd_work: hot plug detection worker
@@ -306,6 +307,7 @@ struct zynqmp_dp {
 	struct drm_bridge bridge;
 	struct work_struct hpd_work;
 	struct work_struct hpd_irq_work;
+	struct completion aux_done;
 	struct mutex lock;
 
 	struct drm_bridge *next_bridge;
@@ -942,12 +944,15 @@ static int zynqmp_dp_aux_cmd_submit(struct zynqmp_dp *dp, u32 cmd, u16 addr,
 				    u8 *buf, u8 bytes, u8 *reply)
 {
 	bool is_read = (cmd & AUX_READ_BIT) ? true : false;
+	unsigned long time_left;
 	u32 reg, i;
 
 	reg = zynqmp_dp_read(dp, ZYNQMP_DP_INTERRUPT_SIGNAL_STATE);
 	if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REQUEST)
 		return -EBUSY;
 
+	reinit_completion(&dp->aux_done);
+
 	zynqmp_dp_write(dp, ZYNQMP_DP_AUX_ADDRESS, addr);
 	if (!is_read)
 		for (i = 0; i < bytes; i++)
@@ -962,17 +967,14 @@ static int zynqmp_dp_aux_cmd_submit(struct zynqmp_dp *dp, u32 cmd, u16 addr,
 	zynqmp_dp_write(dp, ZYNQMP_DP_AUX_COMMAND, reg);
 
 	/* Wait for reply to be delivered upto 2ms */
-	for (i = 0; ; i++) {
-		reg = zynqmp_dp_read(dp, ZYNQMP_DP_INTERRUPT_SIGNAL_STATE);
-		if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY)
-			break;
+	time_left = wait_for_completion_timeout(&dp->aux_done,
+						msecs_to_jiffies(2));
+	if (!time_left)
+		return -ETIMEDOUT;
 
-		if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY_TIMEOUT ||
-		    i == 2)
-			return -ETIMEDOUT;
-
-		usleep_range(1000, 1100);
-	}
+	reg = zynqmp_dp_read(dp, ZYNQMP_DP_INTERRUPT_SIGNAL_STATE);
+	if (reg & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY_TIMEOUT)
+		return -ETIMEDOUT;
 
 	reg = zynqmp_dp_read(dp, ZYNQMP_DP_AUX_REPLY_CODE);
 	if (reply)
@@ -1056,6 +1058,9 @@ static int zynqmp_dp_aux_init(struct zynqmp_dp *dp)
 			(w << ZYNQMP_DP_AUX_CLK_DIVIDER_AUX_FILTER_SHIFT) |
 			(rate / (1000 * 1000)));
 
+	zynqmp_dp_write(dp, ZYNQMP_DP_INT_EN, ZYNQMP_DP_INT_REPLY_RECEIVED |
+					      ZYNQMP_DP_INT_REPLY_TIMEOUT);
+
 	dp->aux.name = "ZynqMP DP AUX";
 	dp->aux.dev = dp->dev;
 	dp->aux.drm_dev = dp->bridge.dev;
@@ -1073,6 +1078,9 @@ static int zynqmp_dp_aux_init(struct zynqmp_dp *dp)
 static void zynqmp_dp_aux_cleanup(struct zynqmp_dp *dp)
 {
 	drm_dp_aux_unregister(&dp->aux);
+
+	zynqmp_dp_write(dp, ZYNQMP_DP_INT_DS, ZYNQMP_DP_INT_REPLY_RECEIVED |
+					      ZYNQMP_DP_INT_REPLY_TIMEOUT);
 }
 
 /* -----------------------------------------------------------------------------
@@ -1730,6 +1738,12 @@ static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
 	if (status & ZYNQMP_DP_INT_HPD_IRQ)
 		schedule_work(&dp->hpd_irq_work);
 
+	if (status & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY)
+		complete(&dp->aux_done);
+
+	if (status & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_REPLY_TIMEOUT)
+		complete(&dp->aux_done);
+
 	return IRQ_HANDLED;
 }
 
@@ -1753,6 +1767,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
 	dp->dpsub = dpsub;
 	dp->status = connector_status_disconnected;
 	mutex_init(&dp->lock);
+	init_completion(&dp->aux_done);
 
 	INIT_WORK(&dp->hpd_work, zynqmp_dp_hpd_work_func);
 	INIT_WORK(&dp->hpd_irq_work, zynqmp_dp_hpd_irq_work_func);
-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 6/8] drm: zynqmp_dp: Split off several helper functions

[Sean Anderson]

In preparation for supporting compliance testing, split off several
helper functions. No functional change intended.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---

(no changes since v1)

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 49 ++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index babfa3581014..e0ab3b3e8580 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -636,6 +636,7 @@ static void zynqmp_dp_adjust_train(struct zynqmp_dp *dp,
 /**
  * zynqmp_dp_update_vs_emph - Update the training values
  * @dp: DisplayPort IP core structure
+ * @train_set: A set of training values
  *
  * Update the training values based on the request from sink. The mapped values
  * are predefined, and values(vs, pe, pc) are from the device manual.
@@ -643,12 +644,12 @@ static void zynqmp_dp_adjust_train(struct zynqmp_dp *dp,
  * Return: 0 if vs and emph are updated successfully, or the error code returned
  * by drm_dp_dpcd_write().
  */
-static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp)
+static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp, u8 *train_set)
 {
 	unsigned int i;
 	int ret;
 
-	ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, dp->train_set,
+	ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, train_set,
 				dp->mode.lane_cnt);
 	if (ret < 0)
 		return ret;
@@ -656,7 +657,7 @@ static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp)
 	for (i = 0; i < dp->mode.lane_cnt; i++) {
 		u32 reg = ZYNQMP_DP_SUB_TX_PHY_PRECURSOR_LANE_0 + i * 4;
 		union phy_configure_opts opts = { 0 };
-		u8 train = dp->train_set[i];
+		u8 train = train_set[i];
 
 		opts.dp.voltage[0] = (train & DP_TRAIN_VOLTAGE_SWING_MASK)
 				   >> DP_TRAIN_VOLTAGE_SWING_SHIFT;
@@ -700,7 +701,7 @@ static int zynqmp_dp_link_train_cr(struct zynqmp_dp *dp)
 	 * So, This loop should exit before 512 iterations
 	 */
 	for (max_tries = 0; max_tries < 512; max_tries++) {
-		ret = zynqmp_dp_update_vs_emph(dp);
+		ret = zynqmp_dp_update_vs_emph(dp, dp->train_set);
 		if (ret)
 			return ret;
 
@@ -765,7 +766,7 @@ static int zynqmp_dp_link_train_ce(struct zynqmp_dp *dp)
 		return ret;
 
 	for (tries = 0; tries < DP_MAX_TRAINING_TRIES; tries++) {
-		ret = zynqmp_dp_update_vs_emph(dp);
+		ret = zynqmp_dp_update_vs_emph(dp, dp->train_set);
 		if (ret)
 			return ret;
 
@@ -788,28 +789,29 @@ static int zynqmp_dp_link_train_ce(struct zynqmp_dp *dp)
 }
 
 /**
- * zynqmp_dp_train - Train the link
+ * zynqmp_dp_setup() - Set up major link parameters
  * @dp: DisplayPort IP core structure
+ * @bw_code: The link bandwidth as a multiple of 270 MHz
+ * @lane_cnt: The number of lanes to use
+ * @enhanced: Use enhanced framing
+ * @downspread: Enable spread-spectrum clocking
  *
- * Return: 0 if all trains are done successfully, or corresponding error code.
+ * Return: 0 on success, or -errno on failure
  */
-static int zynqmp_dp_train(struct zynqmp_dp *dp)
+static int zynqmp_dp_setup(struct zynqmp_dp *dp, u8 bw_code, u8 lane_cnt,
+			   bool enhanced, bool downspread)
 {
 	u32 reg;
-	u8 bw_code = dp->mode.bw_code;
-	u8 lane_cnt = dp->mode.lane_cnt;
 	u8 aux_lane_cnt = lane_cnt;
-	bool enhanced;
 	int ret;
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_LANE_COUNT_SET, lane_cnt);
-	enhanced = drm_dp_enhanced_frame_cap(dp->dpcd);
 	if (enhanced) {
 		zynqmp_dp_write(dp, ZYNQMP_DP_ENHANCED_FRAME_EN, 1);
 		aux_lane_cnt |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
 	}
 
-	if (dp->dpcd[3] & 0x1) {
+	if (downspread) {
 		zynqmp_dp_write(dp, ZYNQMP_DP_DOWNSPREAD_CTL, 1);
 		drm_dp_dpcd_writeb(&dp->aux, DP_DOWNSPREAD_CTRL,
 				   DP_SPREAD_AMP_0_5);
@@ -852,8 +854,25 @@ static int zynqmp_dp_train(struct zynqmp_dp *dp)
 	}
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_PHY_CLOCK_SELECT, reg);
-	ret = zynqmp_dp_phy_ready(dp);
-	if (ret < 0)
+	return zynqmp_dp_phy_ready(dp);
+}
+
+
+/**
+ * zynqmp_dp_train - Train the link
+ * @dp: DisplayPort IP core structure
+ *
+ * Return: 0 if all trains are done successfully, or corresponding error code.
+ */
+static int zynqmp_dp_train(struct zynqmp_dp *dp)
+{
+	int ret;
+
+	ret = zynqmp_dp_setup(dp, dp->mode.bw_code, dp->mode.lane_cnt,
+			      drm_dp_enhanced_frame_cap(dp->dpcd),
+			      dp->dpcd[DP_MAX_DOWNSPREAD] &
+			      DP_MAX_DOWNSPREAD_0_5);
+	if (ret)
 		return ret;
 
 	zynqmp_dp_write(dp, ZYNQMP_DP_SCRAMBLING_DISABLE, 1);
-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 7/8] drm: zynqmp_dp: Take dp->lock in zynqmp_dp_hpd_work_func

[Sean Anderson]

Add a non-locking version of zynqmp_dp_bridge_detect and use it in
zynqmp_dp_hpd_work_func so we can take the lock explicitly. This will
make it easier to check for hpd_ignore when we add debugfs support.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

(no changes since v3)

Changes in v3:
- New

 drivers/gpu/drm/xlnx/zynqmp_dp.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index e0ab3b3e8580..f5203ffa3c75 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -1567,14 +1567,13 @@ static int zynqmp_dp_bridge_atomic_check(struct drm_bridge *bridge,
 	return 0;
 }
 
-static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *bridge)
+static enum drm_connector_status __zynqmp_dp_bridge_detect(struct zynqmp_dp *dp)
 {
-	struct zynqmp_dp *dp = bridge_to_dp(bridge);
 	struct zynqmp_dp_link_config *link_config = &dp->link_config;
 	u32 state, i;
 	int ret;
 
-	mutex_lock(&dp->lock);
+	lockdep_assert_held(&dp->lock);
 
 	/*
 	 * This is from heuristic. It takes some delay (ex, 100 ~ 500 msec) to
@@ -1603,16 +1602,26 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid
 					       dp->num_lanes);
 
 		dp->status = connector_status_connected;
-		mutex_unlock(&dp->lock);
 		return connector_status_connected;
 	}
 
 disconnected:
 	dp->status = connector_status_disconnected;
-	mutex_unlock(&dp->lock);
 	return connector_status_disconnected;
 }
 
+static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *bridge)
+{
+	struct zynqmp_dp *dp = bridge_to_dp(bridge);
+	enum drm_connector_status ret;
+
+	mutex_lock(&dp->lock);
+	ret = __zynqmp_dp_bridge_detect(dp);
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
 static const struct drm_edid *zynqmp_dp_bridge_edid_read(struct drm_bridge *bridge,
 							 struct drm_connector *connector)
 {
@@ -1696,7 +1705,10 @@ static void zynqmp_dp_hpd_work_func(struct work_struct *work)
 	struct zynqmp_dp *dp = container_of(work, struct zynqmp_dp, hpd_work);
 	enum drm_connector_status status;
 
-	status = zynqmp_dp_bridge_detect(&dp->bridge);
+	mutex_lock(&dp->lock);
+	status = __zynqmp_dp_bridge_detect(dp);
+	mutex_unlock(&dp->lock);
+
 	drm_bridge_hpd_notify(&dp->bridge, status);
 }
 
-- 
2.35.1.1320.gc452695387.dirty

[PATCH v6 8/8] drm: zynqmp_dp: Add debugfs interface for compliance testing

[Sean Anderson]

Add a debugfs interface for exercising the various test modes supported
by the DisplayPort controller. This allows performing compliance
testing, or performing signal integrity measurements on a failing link.
At the moment, we do not support sink-driven link quality testing,
although such support would be fairly easy to add.

Additionally, add some debugfs files for ignoring AUX errors and HPD
events, as this can allow testing with equipment that cannot emulate a
DPRX.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

(no changes since v2)

Changes in v2:
- Document debugfs files
- Add ignore_aux_errors and ignore_hpd debugfs files to replace earlier
  implicit functionality
- Attempt to fix unreproducable, spurious build warning

 Documentation/gpu/drivers.rst    |   1 +
 Documentation/gpu/zynqmp.rst     | 149 +++++++
 MAINTAINERS                      |   1 +
 drivers/gpu/drm/xlnx/zynqmp_dp.c | 682 ++++++++++++++++++++++++++++++-
 4 files changed, 830 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/gpu/zynqmp.rst

diff --git a/Documentation/gpu/drivers.rst b/Documentation/gpu/drivers.rst
index b899cbc5c2b4..187201aedbe5 100644
--- a/Documentation/gpu/drivers.rst
+++ b/Documentation/gpu/drivers.rst
@@ -22,6 +22,7 @@ GPU Driver Documentation
    afbc
    komeda-kms
    panfrost
+   zynqmp
 
 .. only::  subproject and html
 
diff --git a/Documentation/gpu/zynqmp.rst b/Documentation/gpu/zynqmp.rst
new file mode 100644
index 000000000000..f57bfa0ad6ec
--- /dev/null
+++ b/Documentation/gpu/zynqmp.rst
@@ -0,0 +1,149 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+===============================================
+Xilinx ZynqMP Ultrascale+ DisplayPort Subsystem
+===============================================
+
+This subsystem handles DisplayPort video and audio output on the ZynqMP. It
+supports in-memory framebuffers with the DisplayPort DMA controller
+(xilinx-dpdma), as well as "live" video and audio from the programmable logic
+(PL). This subsystem can perform several transformations, including color space
+conversion, alpha blending, and audio mixing, although not all features are
+currently supported.
+
+debugfs
+-------
+
+To support debugging and compliance testing, several test modes can be enabled
+though debugfs. The following files in /sys/kernel/debug/dri/X/DP-1/test/
+control the DisplayPort test modes:
+
+active:
+        Writing a 1 to this file will activate test mode, and writing a 0 will
+        deactivate test mode. Writing a 1 or 0 when the test mode is already
+        active/inactive will re-activate/re-deactivate test mode. When test
+        mode is inactive, changes made to other files will have no (immediate)
+        effect, although the settings will be saved for when test mode is
+        activated. When test mode is active, changes made to other files will
+        apply immediately.
+
+custom:
+        Custom test pattern value
+
+downspread:
+        Enable/disable clock downspreading (spread-spectrum clocking) by
+        writing 1/0
+
+enhanced:
+        Enable/disable enhanced framing
+
+ignore_aux_errors:
+        Ignore AUX errors when set to 1. Writes to this file take effect
+        immediately (regardless of whether test mode is active) and affect all
+        AUX transfers.
+
+ignore_hpd:
+        Ignore hotplug events (such as cable removals or monitor link
+        retraining requests) when set to 1. Writes to this file take effect
+        immediately (regardless of whether test mode is active).
+
+laneX_preemphasis:
+        Preemphasis from 0 (lowest) to 2 (highest) for lane X
+
+laneX_swing:
+        Voltage swing from 0 (lowest) to 3 (highest) for lane X
+
+lanes:
+        Number of lanes to use (1, 2, or 4)
+
+pattern:
+        Test pattern. May be one of:
+
+                video
+                        Use regular video input
+
+                symbol-error
+                        Symbol error measurement pattern
+
+                prbs7
+                        Output of the PRBS7 (x^7 + x^6 + 1) polynomial
+
+                80bit-custom
+                        A custom 80-bit pattern
+
+                cp2520
+                        HBR2 compliance eye pattern
+
+                tps1
+                        Link training symbol pattern TPS1 (/D10.2/)
+
+                tps2
+                        Link training symbol pattern TPS2
+
+                tps3
+                        Link training symbol pattern TPS3 (for HBR2)
+
+rate:
+        Rate in hertz. One of
+
+                * 5400000000 (HBR2)
+                * 2700000000 (HBR)
+                * 1620000000 (RBR)
+
+You can dump the displayport test settings with the following command::
+
+        for prop in /sys/kernel/debug/dri/1/DP-1/test/*; do
+                printf '%-17s ' ${prop##*/}
+                if [ ${prop##*/} = custom ]; then
+                        hexdump -C $prop | head -1
+                else
+                        cat $prop
+                fi
+        done
+
+The output could look something like::
+
+        active            1
+        custom            00000000  00 00 00 00 00 00 00 00  00 00                    |..........|
+        downspread        0
+        enhanced          1
+        ignore_aux_errors 1
+        ignore_hpd        1
+        lane0_preemphasis 0
+        lane0_swing       3
+        lane1_preemphasis 0
+        lane1_swing       3
+        lanes             2
+        pattern           prbs7
+        rate              1620000000
+
+The recommended test procedure is to connect the board to a monitor,
+configure test mode, activate test mode, and then disconnect the cable
+and connect it to your test equipment of choice. For example, one
+sequence of commands could be::
+
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/enhanced
+        echo tps1 > /sys/kernel/debug/dri/1/DP-1/test/pattern
+        echo 1620000000 > /sys/kernel/debug/dri/1/DP-1/test/rate
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/ignore_aux_errors
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/ignore_hpd
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/active
+
+at which point the cable could be disconnected from the monitor.
+
+Internals
+---------
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_disp.h
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dpsub.h
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_kms.h
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_disp.c
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dp.c
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dpsub.c
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_kms.c
diff --git a/MAINTAINERS b/MAINTAINERS
index e72268c0fd26..ff387af9350d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7570,6 +7570,7 @@ L:	dri-devel@lists.freedesktop.org
 S:	Maintained
 T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
 F:	Documentation/devicetree/bindings/display/xlnx/
+F:	Documentation/gpu/zynqmp.rst
 F:	drivers/gpu/drm/xlnx/
 
 DRM GPU SCHEDULER
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index f5203ffa3c75..f76107430bd0 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -18,7 +18,9 @@
 #include <drm/drm_modes.h>
 #include <drm/drm_of.h>
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
+#include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/io.h>
@@ -51,6 +53,7 @@ MODULE_PARM_DESC(power_on_delay_ms, "DP power on delay in msec (default: 4)");
 #define ZYNQMP_DP_LANE_COUNT_SET			0x4
 #define ZYNQMP_DP_ENHANCED_FRAME_EN			0x8
 #define ZYNQMP_DP_TRAINING_PATTERN_SET			0xc
+#define ZYNQMP_DP_LINK_QUAL_PATTERN_SET			0x10
 #define ZYNQMP_DP_SCRAMBLING_DISABLE			0x14
 #define ZYNQMP_DP_DOWNSPREAD_CTL			0x18
 #define ZYNQMP_DP_SOFTWARE_RESET			0x1c
@@ -64,6 +67,9 @@ MODULE_PARM_DESC(power_on_delay_ms, "DP power on delay in msec (default: 4)");
 							 ZYNQMP_DP_SOFTWARE_RESET_STREAM3 | \
 							 ZYNQMP_DP_SOFTWARE_RESET_STREAM4 | \
 							 ZYNQMP_DP_SOFTWARE_RESET_AUX)
+#define ZYNQMP_DP_COMP_PATTERN_80BIT_1			0x20
+#define ZYNQMP_DP_COMP_PATTERN_80BIT_2			0x24
+#define ZYNQMP_DP_COMP_PATTERN_80BIT_3			0x28
 
 /* Core enable registers */
 #define ZYNQMP_DP_TRANSMITTER_ENABLE			0x80
@@ -207,6 +213,7 @@ MODULE_PARM_DESC(power_on_delay_ms, "DP power on delay in msec (default: 4)");
 #define ZYNQMP_DP_TX_PHY_POWER_DOWN_LANE_2		BIT(2)
 #define ZYNQMP_DP_TX_PHY_POWER_DOWN_LANE_3		BIT(3)
 #define ZYNQMP_DP_TX_PHY_POWER_DOWN_ALL			0xf
+#define ZYNQMP_DP_TRANSMIT_PRBS7			0x230
 #define ZYNQMP_DP_PHY_PRECURSOR_LANE_0			0x23c
 #define ZYNQMP_DP_PHY_PRECURSOR_LANE_1			0x240
 #define ZYNQMP_DP_PHY_PRECURSOR_LANE_2			0x244
@@ -274,6 +281,69 @@ struct zynqmp_dp_config {
 	u8 bpp;
 };
 
+/**
+ * enum test_pattern - Test patterns for test testing
+ * @TEST_VIDEO: Use regular video input
+ * @TEST_SYMBOL_ERROR: Symbol error measurement pattern
+ * @TEST_PRBS7: Output of the PRBS7 (x^7 + x^6 + 1) polynomial
+ * @TEST_80BIT_CUSTOM: A custom 80-bit pattern
+ * @TEST_CP2520: HBR2 compliance eye pattern
+ * @TEST_TPS1: Link training symbol pattern TPS1 (/D10.2/)
+ * @TEST_TPS2: Link training symbol pattern TPS2
+ * @TEST_TPS3: Link training symbol pattern TPS3 (for HBR2)
+ */
+enum test_pattern {
+	TEST_VIDEO,
+	TEST_TPS1,
+	TEST_TPS2,
+	TEST_TPS3,
+	TEST_SYMBOL_ERROR,
+	TEST_PRBS7,
+	TEST_80BIT_CUSTOM,
+	TEST_CP2520,
+};
+
+static const char *const test_pattern_str[] = {
+	[TEST_VIDEO] = "video",
+	[TEST_TPS1] = "tps1",
+	[TEST_TPS2] = "tps2",
+	[TEST_TPS3] = "tps3",
+	[TEST_SYMBOL_ERROR] = "symbol-error",
+	[TEST_PRBS7] = "prbs7",
+	[TEST_80BIT_CUSTOM] = "80bit-custom",
+	[TEST_CP2520] = "cp2520",
+};
+
+/**
+ * struct zynqmp_dp_test - Configuration for test mode
+ * @pattern: The test pattern
+ * @enhanced: Use enhanced framing
+ * @downspread: Use SSC
+ * @active: Whether test mode is active
+ * @custom: Custom pattern for %TEST_80BIT_CUSTOM
+ * @train_set: Voltage/preemphasis settings
+ * @bw_code: Bandwidth code for the link
+ * @link_cnt: Number of lanes
+ */
+struct zynqmp_dp_test {
+	enum test_pattern pattern;
+	bool enhanced, downspread, active;
+	u8 custom[10];
+	u8 train_set[ZYNQMP_DP_MAX_LANES];
+	u8 bw_code;
+	u8 link_cnt;
+};
+
+/**
+ * struct zynqmp_dp_train_set_priv - Private data for train_set debugfs files
+ * @dp: DisplayPort IP core structure
+ * @lane: The lane for this file
+ */
+struct zynqmp_dp_train_set_priv {
+	struct zynqmp_dp *dp;
+	int lane;
+};
+
 /**
  * struct zynqmp_dp - Xilinx DisplayPort core
  * @dev: device structure
@@ -284,23 +354,28 @@ struct zynqmp_dp_config {
  * @irq: irq
  * @bridge: DRM bridge for the DP encoder
  * @next_bridge: The downstream bridge
+ * @test: Configuration for test mode
  * @config: IP core configuration from DTS
  * @aux: aux channel
  * @aux_done: Completed when we get an AUX reply or timeout
+ * @ignore_aux_errors: If set, AUX errors are suppressed
  * @phy: PHY handles for DP lanes
  * @num_lanes: number of enabled phy lanes
  * @hpd_work: hot plug detection worker
  * @hpd_irq_work: hot plug detection IRQ worker
+ * @ignore_hpd: If set, HPD events and IRQs are ignored
  * @status: connection status
  * @enabled: flag to indicate if the device is enabled
  * @dpcd: DP configuration data from currently connected sink device
  * @link_config: common link configuration between IP core and sink device
  * @mode: current mode between IP core and sink device
  * @train_set: set of training data
+ * @debugfs_train_set: Debugfs private data for @train_set
  *
  * @lock covers the link configuration in this struct and the device's
- * registers. It does not cover @aux. It is not strictly required for any of
- * the members which are only modified at probe/remove time (e.g. @dev).
+ * registers. It does not cover @aux or @ignore_aux_errors. It is not strictly
+ * required for any of the members which are only modified at probe/remove time
+ * (e.g. @dev).
  */
 struct zynqmp_dp {
 	struct drm_dp_aux aux;
@@ -320,9 +395,13 @@ struct zynqmp_dp {
 	enum drm_connector_status status;
 	int irq;
 	bool enabled;
+	bool ignore_aux_errors;
+	bool ignore_hpd;
 
+	struct zynqmp_dp_train_set_priv debugfs_train_set[ZYNQMP_DP_MAX_LANES];
 	struct zynqmp_dp_mode mode;
 	struct zynqmp_dp_link_config link_config;
+	struct zynqmp_dp_test test;
 	struct zynqmp_dp_config config;
 	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 	u8 train_set[ZYNQMP_DP_MAX_LANES];
@@ -1035,6 +1114,8 @@ zynqmp_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 
 		if (dp->status == connector_status_disconnected) {
 			dev_dbg(dp->dev, "no connected aux device\n");
+			if (dp->ignore_aux_errors)
+				goto fake_response;
 			return -ENODEV;
 		}
 
@@ -1043,7 +1124,13 @@ zynqmp_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 
 	dev_dbg(dp->dev, "failed to do aux transfer (%d)\n", ret);
 
-	return ret;
+	if (!dp->ignore_aux_errors)
+		return ret;
+
+fake_response:
+	msg->reply = DP_AUX_NATIVE_REPLY_ACK;
+	memset(msg->buffer, 0, msg->size);
+	return msg->size;
 }
 
 /**
@@ -1659,6 +1746,584 @@ zynqmp_dp_bridge_get_input_bus_fmts(struct drm_bridge *bridge,
 		return zynqmp_dp_bridge_default_bus_fmts(num_input_fmts);
 }
 
+/* -----------------------------------------------------------------------------
+ * debugfs
+ */
+
+/**
+ * zynqmp_dp_set_test_pattern() - Configure the link for a test pattern
+ * @dp: DisplayPort IP core structure
+ * @pattern: The test pattern to configure
+ * @custom: The custom pattern to use if @pattern is %TEST_80BIT_CUSTOM
+ *
+ * Return: 0 on success, or negative errno on (DPCD) failure
+ */
+static int zynqmp_dp_set_test_pattern(struct zynqmp_dp *dp,
+				      enum test_pattern pattern,
+				      u8 *const custom)
+{
+	bool scramble = false;
+	u32 train_pattern = 0;
+	u32 link_pattern = 0;
+	u8 dpcd_train = 0;
+	u8 dpcd_link = 0;
+	int ret;
+
+	switch (pattern) {
+	case TEST_TPS1:
+		train_pattern = 1;
+		break;
+	case TEST_TPS2:
+		train_pattern = 2;
+		break;
+	case TEST_TPS3:
+		train_pattern = 3;
+		break;
+	case TEST_SYMBOL_ERROR:
+		scramble = true;
+		link_pattern = DP_PHY_TEST_PATTERN_ERROR_COUNT;
+		break;
+	case TEST_PRBS7:
+		/* We use a dedicated register to enable PRBS7 */
+		dpcd_link = DP_LINK_QUAL_PATTERN_ERROR_RATE;
+		break;
+	case TEST_80BIT_CUSTOM: {
+		const u8 *p = custom;
+
+		link_pattern = DP_LINK_QUAL_PATTERN_80BIT_CUSTOM;
+
+		zynqmp_dp_write(dp, ZYNQMP_DP_COMP_PATTERN_80BIT_1,
+				(p[3] << 24) | (p[2] << 16) | (p[1] << 8) | p[0]);
+		zynqmp_dp_write(dp, ZYNQMP_DP_COMP_PATTERN_80BIT_2,
+				(p[7] << 24) | (p[6] << 16) | (p[5] << 8) | p[4]);
+		zynqmp_dp_write(dp, ZYNQMP_DP_COMP_PATTERN_80BIT_3,
+				(p[9] << 8) | p[8]);
+		break;
+	}
+	case TEST_CP2520:
+		link_pattern = DP_LINK_QUAL_PATTERN_CP2520_PAT_1;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		fallthrough;
+	case TEST_VIDEO:
+		scramble = true;
+	}
+
+	zynqmp_dp_write(dp, ZYNQMP_DP_SCRAMBLING_DISABLE, !scramble);
+	zynqmp_dp_write(dp, ZYNQMP_DP_TRAINING_PATTERN_SET, train_pattern);
+	zynqmp_dp_write(dp, ZYNQMP_DP_LINK_QUAL_PATTERN_SET, link_pattern);
+	zynqmp_dp_write(dp, ZYNQMP_DP_TRANSMIT_PRBS7, pattern == TEST_PRBS7);
+
+	dpcd_link = dpcd_link ?: link_pattern;
+	dpcd_train = train_pattern;
+	if (!scramble)
+		dpcd_train |= DP_LINK_SCRAMBLING_DISABLE;
+
+	if (dp->dpcd[DP_DPCD_REV] < 0x12) {
+		if (pattern == TEST_CP2520)
+			dev_warn(dp->dev,
+				"can't set sink link quality pattern to CP2520 for DPCD < r1.2; error counters will be invalid\n");
+		else
+			dpcd_train |= FIELD_PREP(DP_LINK_QUAL_PATTERN_11_MASK,
+						 dpcd_link);
+	} else {
+		u8 dpcd_link_lane[ZYNQMP_DP_MAX_LANES];
+
+		memset(dpcd_link_lane, dpcd_link, ZYNQMP_DP_MAX_LANES);
+		ret = drm_dp_dpcd_write(&dp->aux, DP_LINK_QUAL_LANE0_SET,
+					dpcd_link_lane, ZYNQMP_DP_MAX_LANES);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET, dpcd_train);
+	return ret < 0 ? ret : 0;
+}
+
+static int zynqmp_dp_test_setup(struct zynqmp_dp *dp)
+{
+	return zynqmp_dp_setup(dp, dp->test.bw_code, dp->test.link_cnt,
+			       dp->test.enhanced, dp->test.downspread);
+}
+
+static ssize_t zynqmp_dp_pattern_read(struct file *file, char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct zynqmp_dp *dp = file->private_data;
+	char buf[16];
+	ssize_t ret;
+
+	ret = debugfs_file_get(dentry);
+	if (unlikely(ret))
+		return ret;
+
+	mutex_lock(&dp->lock);
+	ret = snprintf(buf, sizeof(buf), "%s\n",
+		       test_pattern_str[dp->test.pattern]);
+	mutex_unlock(&dp->lock);
+
+	debugfs_file_put(dentry);
+	return simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+}
+
+static ssize_t zynqmp_dp_pattern_write(struct file *file,
+				       const char __user *user_buf,
+				       size_t count, loff_t *ppos)
+{
+
+	struct dentry *dentry = file->f_path.dentry;
+	struct zynqmp_dp *dp = file->private_data;
+	char buf[16];
+	ssize_t ret;
+	int pattern;
+
+	ret = debugfs_file_get(dentry);
+	if (unlikely(ret))
+		return ret;
+
+	ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, user_buf,
+				     count);
+	if (ret < 0)
+		goto out;
+	buf[ret] = '\0';
+
+	pattern = sysfs_match_string(test_pattern_str, buf);
+	if (pattern < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&dp->lock);
+	dp->test.pattern = pattern;
+	if (dp->test.active)
+		ret = zynqmp_dp_set_test_pattern(dp, dp->test.pattern,
+						 dp->test.custom) ?: ret;
+	mutex_unlock(&dp->lock);
+
+out:
+	debugfs_file_put(dentry);
+	return ret;
+}
+
+static const struct file_operations fops_zynqmp_dp_pattern = {
+	.read = zynqmp_dp_pattern_read,
+	.write = zynqmp_dp_pattern_write,
+	.open = simple_open,
+	.llseek = noop_llseek,
+};
+
+static int zynqmp_dp_enhanced_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->lock);
+	*val = dp->test.enhanced;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_enhanced_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+	int ret = 0;
+
+	mutex_lock(&dp->lock);
+	dp->test.enhanced = val;
+	if (dp->test.active)
+		ret = zynqmp_dp_test_setup(dp);
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_enhanced, zynqmp_dp_enhanced_get,
+			 zynqmp_dp_enhanced_set, "%llu\n");
+
+static int zynqmp_dp_downspread_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->lock);
+	*val = dp->test.downspread;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_downspread_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+	int ret = 0;
+
+	mutex_lock(&dp->lock);
+	dp->test.downspread = val;
+	if (dp->test.active)
+		ret = zynqmp_dp_test_setup(dp);
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_downspread, zynqmp_dp_downspread_get,
+			 zynqmp_dp_downspread_set, "%llu\n");
+
+static int zynqmp_dp_active_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->lock);
+	*val = dp->test.active;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_active_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+	int ret = 0;
+
+	mutex_lock(&dp->lock);
+	if (val) {
+		if (val < 2) {
+			ret = zynqmp_dp_test_setup(dp);
+			if (ret)
+				goto out;
+		}
+
+		ret = zynqmp_dp_set_test_pattern(dp, dp->test.pattern,
+						 dp->test.custom);
+		if (ret)
+			goto out;
+
+		ret = zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
+		if (ret)
+			goto out;
+
+		dp->test.active = true;
+	} else {
+		int err;
+
+		dp->test.active = false;
+		err = zynqmp_dp_set_test_pattern(dp, TEST_VIDEO, NULL);
+		if (err)
+			dev_warn(dp->dev, "could not clear test pattern: %d\n",
+				 err);
+		zynqmp_dp_train_loop(dp);
+	}
+out:
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_active, zynqmp_dp_active_get,
+			 zynqmp_dp_active_set, "%llu\n");
+
+static ssize_t zynqmp_dp_custom_read(struct file *file, char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct zynqmp_dp *dp = file->private_data;
+	ssize_t ret;
+
+	ret = debugfs_file_get(dentry);
+	if (unlikely(ret))
+		return ret;
+
+	mutex_lock(&dp->lock);
+	ret = simple_read_from_buffer(user_buf, count, ppos, &dp->test.custom,
+				      sizeof(dp->test.custom));
+	mutex_unlock(&dp->lock);
+
+	debugfs_file_put(dentry);
+	return ret;
+}
+
+static ssize_t zynqmp_dp_custom_write(struct file *file,
+				      const char __user *user_buf,
+				      size_t count, loff_t *ppos)
+{
+
+	struct dentry *dentry = file->f_path.dentry;
+	struct zynqmp_dp *dp = file->private_data;
+	ssize_t ret;
+	char buf[sizeof(dp->test.custom)];
+
+	ret = debugfs_file_get(dentry);
+	if (unlikely(ret))
+		return ret;
+
+	ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
+	if (ret < 0)
+		goto out;
+
+	mutex_lock(&dp->lock);
+	memcpy(dp->test.custom, buf, ret);
+	if (dp->test.active)
+		ret = zynqmp_dp_set_test_pattern(dp, dp->test.pattern,
+						 dp->test.custom) ?: ret;
+	mutex_unlock(&dp->lock);
+
+out:
+	debugfs_file_put(dentry);
+	return ret;
+}
+
+static const struct file_operations fops_zynqmp_dp_custom = {
+	.read = zynqmp_dp_custom_read,
+	.write = zynqmp_dp_custom_write,
+	.open = simple_open,
+	.llseek = noop_llseek,
+};
+
+static int zynqmp_dp_swing_get(void *data, u64 *val)
+{
+	struct zynqmp_dp_train_set_priv *priv = data;
+	struct zynqmp_dp *dp = priv->dp;
+
+	mutex_lock(&dp->lock);
+	*val = dp->test.train_set[priv->lane] & DP_TRAIN_VOLTAGE_SWING_MASK;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_swing_set(void *data, u64 val)
+{
+	struct zynqmp_dp_train_set_priv *priv = data;
+	struct zynqmp_dp *dp = priv->dp;
+	u8 *train_set = &dp->test.train_set[priv->lane];
+	int ret = 0;
+
+	if (val > 3)
+		return -EINVAL;
+
+	mutex_lock(&dp->lock);
+	*train_set &= ~(DP_TRAIN_MAX_SWING_REACHED |
+			DP_TRAIN_VOLTAGE_SWING_MASK);
+	*train_set |= val;
+	if (val == 3)
+		*train_set |= DP_TRAIN_MAX_SWING_REACHED;
+
+	if (dp->test.active)
+		ret = zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_swing, zynqmp_dp_swing_get,
+			 zynqmp_dp_swing_set, "%llu\n");
+
+static int zynqmp_dp_preemphasis_get(void *data, u64 *val)
+{
+	struct zynqmp_dp_train_set_priv *priv = data;
+	struct zynqmp_dp *dp = priv->dp;
+
+	mutex_lock(&dp->lock);
+	*val = FIELD_GET(DP_TRAIN_PRE_EMPHASIS_MASK,
+			 dp->test.train_set[priv->lane]);
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_preemphasis_set(void *data, u64 val)
+{
+	struct zynqmp_dp_train_set_priv *priv = data;
+	struct zynqmp_dp *dp = priv->dp;
+	u8 *train_set = &dp->test.train_set[priv->lane];
+	int ret = 0;
+
+	if (val > 2)
+		return -EINVAL;
+
+	mutex_lock(&dp->lock);
+	*train_set &= ~(DP_TRAIN_MAX_PRE_EMPHASIS_REACHED |
+			DP_TRAIN_PRE_EMPHASIS_MASK);
+	*train_set |= val;
+	if (val == 2)
+		*train_set |= DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
+
+	if (dp->test.active)
+		ret = zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_preemphasis, zynqmp_dp_preemphasis_get,
+			 zynqmp_dp_preemphasis_set, "%llu\n");
+
+static int zynqmp_dp_lanes_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->lock);
+	*val = dp->test.link_cnt;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_lanes_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+	int ret = 0;
+
+	if (val > ZYNQMP_DP_MAX_LANES)
+		return -EINVAL;
+
+	mutex_lock(&dp->lock);
+	if (val > dp->num_lanes) {
+		ret = -EINVAL;
+	} else {
+		dp->test.link_cnt = val;
+		if (dp->test.active)
+			ret = zynqmp_dp_test_setup(dp);
+	}
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_lanes, zynqmp_dp_lanes_get,
+			 zynqmp_dp_lanes_set, "%llu\n");
+
+static int zynqmp_dp_rate_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->lock);
+	*val = drm_dp_bw_code_to_link_rate(dp->test.bw_code) * 10000;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_rate_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+	int link_rate;
+	int ret = 0;
+	u8 bw_code;
+
+	if (do_div(val, 10000))
+		return -EINVAL;
+
+	bw_code = drm_dp_link_rate_to_bw_code(val);
+	link_rate = drm_dp_bw_code_to_link_rate(bw_code);
+	if (val != link_rate)
+		return -EINVAL;
+
+	if (bw_code != DP_LINK_BW_1_62 && bw_code != DP_LINK_BW_2_7 &&
+	    bw_code != DP_LINK_BW_5_4)
+		return -EINVAL;
+
+	mutex_lock(&dp->lock);
+	dp->test.bw_code = bw_code;
+	if (dp->test.active)
+		ret = zynqmp_dp_test_setup(dp);
+	mutex_unlock(&dp->lock);
+
+	return ret;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_rate, zynqmp_dp_rate_get,
+			 zynqmp_dp_rate_set, "%llu\n");
+
+static int zynqmp_dp_ignore_aux_errors_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->aux.hw_mutex);
+	*val = dp->ignore_aux_errors;
+	mutex_unlock(&dp->aux.hw_mutex);
+	return 0;
+}
+
+static int zynqmp_dp_ignore_aux_errors_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+
+	if (val != !!val)
+		return -EINVAL;
+
+	mutex_lock(&dp->aux.hw_mutex);
+	dp->ignore_aux_errors = val;
+	mutex_unlock(&dp->aux.hw_mutex);
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_ignore_aux_errors,
+			 zynqmp_dp_ignore_aux_errors_get,
+			 zynqmp_dp_ignore_aux_errors_set, "%llu\n");
+
+static int zynqmp_dp_ignore_hpd_get(void *data, u64 *val)
+{
+	struct zynqmp_dp *dp = data;
+
+	mutex_lock(&dp->lock);
+	*val = dp->ignore_hpd;
+	mutex_unlock(&dp->lock);
+	return 0;
+}
+
+static int zynqmp_dp_ignore_hpd_set(void *data, u64 val)
+{
+	struct zynqmp_dp *dp = data;
+
+	if (val != !!val)
+		return -EINVAL;
+
+	mutex_lock(&dp->lock);
+	dp->ignore_hpd = val;
+	mutex_lock(&dp->lock);
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_ignore_hpd, zynqmp_dp_ignore_hpd_get,
+			 zynqmp_dp_ignore_hpd_set, "%llu\n");
+
+static void zynqmp_dp_bridge_debugfs_init(struct drm_bridge *bridge,
+					  struct dentry *root)
+{
+	struct zynqmp_dp *dp = bridge_to_dp(bridge);
+	struct dentry *test;
+	int i;
+
+	dp->test.bw_code = DP_LINK_BW_5_4;
+	dp->test.link_cnt = dp->num_lanes;
+
+	test = debugfs_create_dir("test", root);
+#define CREATE_FILE(name) \
+	debugfs_create_file(#name, 0600, test, dp, &fops_zynqmp_dp_##name)
+	CREATE_FILE(pattern);
+	CREATE_FILE(enhanced);
+	CREATE_FILE(downspread);
+	CREATE_FILE(active);
+	CREATE_FILE(custom);
+	CREATE_FILE(rate);
+	CREATE_FILE(lanes);
+	CREATE_FILE(ignore_aux_errors);
+	CREATE_FILE(ignore_hpd);
+
+	for (i = 0; i < dp->num_lanes; i++) {
+		static const char fmt[] = "lane%d_preemphasis";
+		char name[sizeof(fmt)];
+
+		dp->debugfs_train_set[i].dp = dp;
+		dp->debugfs_train_set[i].lane = i;
+
+		snprintf(name, sizeof(name), fmt, i);
+		debugfs_create_file(name, 0600, test,
+				    &dp->debugfs_train_set[i],
+				    &fops_zynqmp_dp_preemphasis);
+
+		snprintf(name, sizeof(name), "lane%d_swing", i);
+		debugfs_create_file(name, 0600, test,
+				    &dp->debugfs_train_set[i],
+				    &fops_zynqmp_dp_swing);
+	}
+}
+
 static const struct drm_bridge_funcs zynqmp_dp_bridge_funcs = {
 	.attach = zynqmp_dp_bridge_attach,
 	.detach = zynqmp_dp_bridge_detach,
@@ -1672,6 +2337,7 @@ static const struct drm_bridge_funcs zynqmp_dp_bridge_funcs = {
 	.detect = zynqmp_dp_bridge_detect,
 	.edid_read = zynqmp_dp_bridge_edid_read,
 	.atomic_get_input_bus_fmts = zynqmp_dp_bridge_get_input_bus_fmts,
+	.debugfs_init = zynqmp_dp_bridge_debugfs_init,
 };
 
 /* -----------------------------------------------------------------------------
@@ -1706,6 +2372,11 @@ static void zynqmp_dp_hpd_work_func(struct work_struct *work)
 	enum drm_connector_status status;
 
 	mutex_lock(&dp->lock);
+	if (dp->ignore_hpd) {
+		mutex_unlock(&dp->lock);
+		return;
+	}
+
 	status = __zynqmp_dp_bridge_detect(dp);
 	mutex_unlock(&dp->lock);
 
@@ -1720,6 +2391,11 @@ static void zynqmp_dp_hpd_irq_work_func(struct work_struct *work)
 	int err;
 
 	mutex_lock(&dp->lock);
+	if (dp->ignore_hpd) {
+		mutex_unlock(&dp->lock);
+		return;
+	}
+
 	err = drm_dp_dpcd_read(&dp->aux, DP_SINK_COUNT, status,
 			       DP_LINK_STATUS_SIZE + 2);
 	if (err < 0) {
-- 
2.35.1.1320.gc452695387.dirty

Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Sean Anderson]

On 8/9/24 15:35, Sean Anderson wrote:
> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
> that's done, it adds debugfs support. The intent is to enable compliance
> testing or to help debug signal-integrity issues.
> 
> Previously, I discussed converting the HPD work(s) to a threaded IRQ. I
> did not end up doing that for this series since the steps would be
> 
> - Add locking
> - Move link retraining to a work function
> - Harden the IRQ
> - Merge the works into a threaded IRQ (omitted)
> 
> Which with the exception of the final step is the same as leaving those
> works as-is. Conversion to a threaded IRQ can be done as a follow-up.
> 
> Changes in v6:
> - Unplug DRM device before removal
> - Fix hang upon driver removal
> - Rebase onto drm-misc/drm-misc-next
> 
> Changes in v5:
> - Rebase onto drm-misc/drm-misc-next
> 
> Changes in v4:
> - Rebase onto drm/drm-next
> 
> Changes in v3:
> - Convert to a hard IRQ
> - Use AUX IRQs instead of polling
> - Take dp->lock in zynqmp_dp_hpd_work_func
> 
> Changes in v2:
> - Split off the HPD IRQ work into another commit
> - Expand the commit message
> - Document hpd_irq_work
> - Document debugfs files
> - Add ignore_aux_errors and ignore_hpd debugfs files to replace earlier
>   implicit functionality
> - Attempt to fix unreproducable, spurious build warning
> - Drop "Optionally ignore DPCD errors" in favor of a debugfs file
>   directly affecting zynqmp_dp_aux_transfer.
> 
> Sean Anderson (8):
>   drm: zynqmp_kms: Unplug DRM device before removal
>   drm: zynqmp_dp: Add locking
>   drm: zynqmp_dp: Don't retrain the link in our IRQ
>   drm: zynqmp_dp: Convert to a hard IRQ
>   drm: zynqmp_dp: Use AUX IRQs instead of polling
>   drm: zynqmp_dp: Split off several helper functions
>   drm: zynqmp_dp: Take dp->lock in zynqmp_dp_hpd_work_func
>   drm: zynqmp_dp: Add debugfs interface for compliance testing
> 
>  Documentation/gpu/drivers.rst     |   1 +
>  Documentation/gpu/zynqmp.rst      | 149 ++++++
>  MAINTAINERS                       |   1 +
>  drivers/gpu/drm/xlnx/zynqmp_dp.c  | 846 ++++++++++++++++++++++++++++--
>  drivers/gpu/drm/xlnx/zynqmp_kms.c |   2 +-
>  5 files changed, 951 insertions(+), 48 deletions(-)
>  create mode 100644 Documentation/gpu/zynqmp.rst
> 

ping

--Sean

Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Tomi Valkeinen]

Hi,

On 01/10/2024 21:31, Sean Anderson wrote:
> On 8/9/24 15:35, Sean Anderson wrote:
>> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
>> that's done, it adds debugfs support. The intent is to enable compliance
>> testing or to help debug signal-integrity issues.

I think the patches 1-7 look fine, and I think I can pick those already 
to drm-misc if you're ok with that.

I'm a bit unsure about patch 8, probably mainly because I don't have 
experience with the compliance testing.

How have you tested this? With some DP analyzer/tester, I presume?

I think none of this (patch 8) is needed by almost anybody. Even among 
zynqmp_dp developers I assume it's very rare to have the hardware for 
this. I wonder if it would make sense to have the debugfs and related 
code behind a compile option (which would be nice as the code wouldn't 
even compiled in), or maybe a module parameter (which would be nice as 
then "anyone" can easily enable it for compliance testing). What do you 
think?

I also somehow recall that there was some discussion earlier about 
how/if other drivers support compliance testing. But I can't find the 
discussion. Do you remember if there was such discussion, and what was 
the conclusion? With a quick look, everything in the debugfs looks 
generic, not xilinx specific.

  Tomi

Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Sean Anderson]

On 10/2/24 10:50, Tomi Valkeinen wrote:
> Hi,
> 
> On 01/10/2024 21:31, Sean Anderson wrote:
>> On 8/9/24 15:35, Sean Anderson wrote:
>>> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
>>> that's done, it adds debugfs support. The intent is to enable compliance
>>> testing or to help debug signal-integrity issues.
> 
> I think the patches 1-7 look fine, and I think I can pick those already to drm-misc if you're ok with that.
> 
> I'm a bit unsure about patch 8, probably mainly because I don't have experience with the compliance testing.
> 
> How have you tested this? With some DP analyzer/tester, I presume?

For my test setup I used an oscilloscope hooked up to the displayport
output using a fixture that broke the signals out to SMA. Since the
oscilloscope cannot emulate a sink, I first had the output connected to
a monitor. Then I disabled HPD and reconnected the output to my fixture.
This process is described in more detail in the documentation.

> I think none of this (patch 8) is needed by almost anybody.

Well, I found it very useful for debugging a signal integrity issue I
was having. Once I could have a look at the signals it was very clear
what the problem was.

> Even among zynqmp_dp developers I assume it's very rare to have the
> hardware for this. I wonder if it would make sense to have the debugfs
> and related code behind a compile option (which would be nice as the
> code wouldn't even compiled in), or maybe a module parameter (which
> would be nice as then "anyone" can easily enable it for compliance
> testing). What do you think?

Other drivers with these features just enabled it unconditionally, so I
didn't bother with any special config.

> I also somehow recall that there was some discussion earlier about
> how/if other drivers support compliance testing. But I can't find the
> discussion. Do you remember if there was such discussion, and what was
> the conclusion? With a quick look, everything in the debugfs looks
> generic, not xilinx specific.

The last it got discussed was back in [1], but I never got any further
response. I agree that some of this is generic, and could probably be
reworked into some internal helpers. But I don't have the bandwidth at
the moment to do that work.

--Sean

[1] http://lore.kernel.org/dri-devel/cda22b0c-8d7c-4ce2-9a7c-3b5ab540fa1f@linux.dev

Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Sean Anderson]

Hi Tomi,

On 10/3/24 10:53, Sean Anderson wrote:
> On 10/2/24 10:50, Tomi Valkeinen wrote:
>> Hi,
>> 
>> On 01/10/2024 21:31, Sean Anderson wrote:
>>> On 8/9/24 15:35, Sean Anderson wrote:
>>>> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
>>>> that's done, it adds debugfs support. The intent is to enable compliance
>>>> testing or to help debug signal-integrity issues.
>> 
>> I think the patches 1-7 look fine, and I think I can pick those already to drm-misc if you're ok with that.
>> 
>> I'm a bit unsure about patch 8, probably mainly because I don't have experience with the compliance testing.
>> 
>> How have you tested this? With some DP analyzer/tester, I presume?
> 
> For my test setup I used an oscilloscope hooked up to the displayport
> output using a fixture that broke the signals out to SMA. Since the
> oscilloscope cannot emulate a sink, I first had the output connected to
> a monitor. Then I disabled HPD and reconnected the output to my fixture.
> This process is described in more detail in the documentation.
> 
>> I think none of this (patch 8) is needed by almost anybody.
> 
> Well, I found it very useful for debugging a signal integrity issue I
> was having. Once I could have a look at the signals it was very clear
> what the problem was.
> 
>> Even among zynqmp_dp developers I assume it's very rare to have the
>> hardware for this. I wonder if it would make sense to have the debugfs
>> and related code behind a compile option (which would be nice as the
>> code wouldn't even compiled in), or maybe a module parameter (which
>> would be nice as then "anyone" can easily enable it for compliance
>> testing). What do you think?
> 
> Other drivers with these features just enabled it unconditionally, so I
> didn't bother with any special config.
> 
>> I also somehow recall that there was some discussion earlier about
>> how/if other drivers support compliance testing. But I can't find the
>> discussion. Do you remember if there was such discussion, and what was
>> the conclusion? With a quick look, everything in the debugfs looks
>> generic, not xilinx specific.
> 
> The last it got discussed was back in [1], but I never got any further
> response. I agree that some of this is generic, and could probably be
> reworked into some internal helpers. But I don't have the bandwidth at
> the moment to do that work.
> 
> --Sean
> 
> [1] http://lore.kernel.org/dri-devel/cda22b0c-8d7c-4ce2-9a7c-3b5ab540fa1f@linux.dev

Does this all make sense to you? At the moment I don't believe I have any
changes I need to resend for (although this series is archived in patchwork [1]
for some reason).

--Sean

[1] https://patchwork.kernel.org/project/dri-devel/list/?series=878338&archive=both

Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Tomi Valkeinen]

Hi,

On 25/10/2024 17:58, Sean Anderson wrote:
> Hi Tomi,
> 
> On 10/3/24 10:53, Sean Anderson wrote:
>> On 10/2/24 10:50, Tomi Valkeinen wrote:
>>> Hi,
>>>
>>> On 01/10/2024 21:31, Sean Anderson wrote:
>>>> On 8/9/24 15:35, Sean Anderson wrote:
>>>>> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
>>>>> that's done, it adds debugfs support. The intent is to enable compliance
>>>>> testing or to help debug signal-integrity issues.
>>>
>>> I think the patches 1-7 look fine, and I think I can pick those already to drm-misc if you're ok with that.
>>>
>>> I'm a bit unsure about patch 8, probably mainly because I don't have experience with the compliance testing.
>>>
>>> How have you tested this? With some DP analyzer/tester, I presume?
>>
>> For my test setup I used an oscilloscope hooked up to the displayport
>> output using a fixture that broke the signals out to SMA. Since the
>> oscilloscope cannot emulate a sink, I first had the output connected to
>> a monitor. Then I disabled HPD and reconnected the output to my fixture.
>> This process is described in more detail in the documentation.
>>
>>> I think none of this (patch 8) is needed by almost anybody.
>>
>> Well, I found it very useful for debugging a signal integrity issue I
>> was having. Once I could have a look at the signals it was very clear
>> what the problem was.
>>
>>> Even among zynqmp_dp developers I assume it's very rare to have the
>>> hardware for this. I wonder if it would make sense to have the debugfs
>>> and related code behind a compile option (which would be nice as the
>>> code wouldn't even compiled in), or maybe a module parameter (which
>>> would be nice as then "anyone" can easily enable it for compliance
>>> testing). What do you think?
>>
>> Other drivers with these features just enabled it unconditionally, so I
>> didn't bother with any special config.
>>
>>> I also somehow recall that there was some discussion earlier about
>>> how/if other drivers support compliance testing. But I can't find the
>>> discussion. Do you remember if there was such discussion, and what was
>>> the conclusion? With a quick look, everything in the debugfs looks
>>> generic, not xilinx specific.
>>
>> The last it got discussed was back in [1], but I never got any further
>> response. I agree that some of this is generic, and could probably be
>> reworked into some internal helpers. But I don't have the bandwidth at
>> the moment to do that work.
>>
>> --Sean
>>
>> [1] http://lore.kernel.org/dri-devel/cda22b0c-8d7c-4ce2-9a7c-3b5ab540fa1f@linux.dev
> 
> Does this all make sense to you? At the moment I don't believe I have any
> changes I need to resend for (although this series is archived in patchwork [1]
> for some reason).
> 
> --Sean
> 
> [1] https://patchwork.kernel.org/project/dri-devel/list/?series=878338&archive=both

I was hoping to get tested-by from amd, as I can't test this properly, 
but it's probably pointless to wait.

The biggest hesitation I have is what I mentioned earlier: this adds a 
lot of code which is not for normal use. It would be nice to split this 
into a separate file, maybe behind a compile option, but I fear that'll 
require a more restructuring of the driver.

So, I think it's fine, I'll apply this tomorrow.

  Tomi

Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support

[Tomi Valkeinen]

Hi Sean,

On 28/10/2024 17:04, Tomi Valkeinen wrote:
> Hi,
> 
> On 25/10/2024 17:58, Sean Anderson wrote:
>> Hi Tomi,
>>
>> On 10/3/24 10:53, Sean Anderson wrote:
>>> On 10/2/24 10:50, Tomi Valkeinen wrote:
>>>> Hi,
>>>>
>>>> On 01/10/2024 21:31, Sean Anderson wrote:
>>>>> On 8/9/24 15:35, Sean Anderson wrote:
>>>>>> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
>>>>>> that's done, it adds debugfs support. The intent is to enable 
>>>>>> compliance
>>>>>> testing or to help debug signal-integrity issues.
>>>>
>>>> I think the patches 1-7 look fine, and I think I can pick those 
>>>> already to drm-misc if you're ok with that.
>>>>
>>>> I'm a bit unsure about patch 8, probably mainly because I don't have 
>>>> experience with the compliance testing.
>>>>
>>>> How have you tested this? With some DP analyzer/tester, I presume?
>>>
>>> For my test setup I used an oscilloscope hooked up to the displayport
>>> output using a fixture that broke the signals out to SMA. Since the
>>> oscilloscope cannot emulate a sink, I first had the output connected to
>>> a monitor. Then I disabled HPD and reconnected the output to my fixture.
>>> This process is described in more detail in the documentation.
>>>
>>>> I think none of this (patch 8) is needed by almost anybody.
>>>
>>> Well, I found it very useful for debugging a signal integrity issue I
>>> was having. Once I could have a look at the signals it was very clear
>>> what the problem was.
>>>
>>>> Even among zynqmp_dp developers I assume it's very rare to have the
>>>> hardware for this. I wonder if it would make sense to have the debugfs
>>>> and related code behind a compile option (which would be nice as the
>>>> code wouldn't even compiled in), or maybe a module parameter (which
>>>> would be nice as then "anyone" can easily enable it for compliance
>>>> testing). What do you think?
>>>
>>> Other drivers with these features just enabled it unconditionally, so I
>>> didn't bother with any special config.
>>>
>>>> I also somehow recall that there was some discussion earlier about
>>>> how/if other drivers support compliance testing. But I can't find the
>>>> discussion. Do you remember if there was such discussion, and what was
>>>> the conclusion? With a quick look, everything in the debugfs looks
>>>> generic, not xilinx specific.
>>>
>>> The last it got discussed was back in [1], but I never got any further
>>> response. I agree that some of this is generic, and could probably be
>>> reworked into some internal helpers. But I don't have the bandwidth at
>>> the moment to do that work.
>>>
>>> --Sean
>>>
>>> [1] http://lore.kernel.org/dri-devel/ 
>>> cda22b0c-8d7c-4ce2-9a7c-3b5ab540fa1f@linux.dev
>>
>> Does this all make sense to you? At the moment I don't believe I have any
>> changes I need to resend for (although this series is archived in 
>> patchwork [1]
>> for some reason).
>>
>> --Sean
>>
>> [1] https://patchwork.kernel.org/project/dri-devel/list/? 
>> series=878338&archive=both
> 
> I was hoping to get tested-by from amd, as I can't test this properly, 
> but it's probably pointless to wait.
> 
> The biggest hesitation I have is what I mentioned earlier: this adds a 
> lot of code which is not for normal use. It would be nice to split this 
> into a separate file, maybe behind a compile option, but I fear that'll 
> require a more restructuring of the driver.
> 
> So, I think it's fine, I'll apply this tomorrow.
> 
>   Tomi
> 

Thanks, pushed.

  Tomi