drm: mali-dp: Add debugfs file for reporting internal errors

Status register contains a lot of bits for reporting internal errors
inside Mali DP. Currently, we just silently ignore all of the errors,
that doesn't help when we are investigating different bugs, especially
on the FPGA models which have a lot of constraints, so we could easily
end up in AXI or underrun errors.

Add a new file called debug that contains an aggregate of the
errors reported by the Mali DP hardware.

E.g:
[root@alarm ~]# cat /sys/kernel/debug/dri/1/debug
[DE] num_errors : 167
[DE] last_error_status  : 0x00000001
[DE] last_error_vblank : 385
[SE] num_errors : 3
[SE] last_error_status  : 0x00e23001
[SE] last_error_vblank : 201

Changes since v2:
- Add lock to protect the errors stats.
- Add possibility to reset the error stats by writing anything to the
  debug file.
Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

drivers/gpu/drm/arm/malidp_drv.c

@@ -17,6 +17,7 @@
 #include <linux/of_graph.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/pm_runtime.h>
+#include <linux/debugfs.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_atomic.h>
@@ -344,6 +345,106 @@ static int malidp_dumb_create(struct drm_file *file_priv,
 	return drm_gem_cma_dumb_create_internal(file_priv, drm, args);
 }
 
+#ifdef CONFIG_DEBUG_FS
+
+static void malidp_error_stats_init(struct malidp_error_stats *error_stats)
+{
+	error_stats->num_errors = 0;
+	error_stats->last_error_status = 0;
+	error_stats->last_error_vblank = -1;
+}
+
+void malidp_error(struct malidp_drm *malidp,
+		  struct malidp_error_stats *error_stats, u32 status,
+		  u64 vblank)
+{
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&malidp->errors_lock, irqflags);
+	error_stats->last_error_status = status;
+	error_stats->last_error_vblank = vblank;
+	error_stats->num_errors++;
+	spin_unlock_irqrestore(&malidp->errors_lock, irqflags);
+}
+
+void malidp_error_stats_dump(const char *prefix,
+			     struct malidp_error_stats error_stats,
+			     struct seq_file *m)
+{
+	seq_printf(m, "[%s] num_errors : %d\n", prefix,
+		   error_stats.num_errors);
+	seq_printf(m, "[%s] last_error_status  : 0x%08x\n", prefix,
+		   error_stats.last_error_status);
+	seq_printf(m, "[%s] last_error_vblank : %lld\n", prefix,
+		   error_stats.last_error_vblank);
+}
+
+static int malidp_show_stats(struct seq_file *m, void *arg)
+{
+	struct drm_device *drm = m->private;
+	struct malidp_drm *malidp = drm->dev_private;
+	unsigned long irqflags;
+	struct malidp_error_stats de_errors, se_errors;
+
+	spin_lock_irqsave(&malidp->errors_lock, irqflags);
+	de_errors = malidp->de_errors;
+	se_errors = malidp->se_errors;
+	spin_unlock_irqrestore(&malidp->errors_lock, irqflags);
+	malidp_error_stats_dump("DE", de_errors, m);
+	malidp_error_stats_dump("SE", se_errors, m);
+	return 0;
+}
+
+static int malidp_debugfs_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, malidp_show_stats, inode->i_private);
+}
+
+static ssize_t malidp_debugfs_write(struct file *file, const char __user *ubuf,
+				    size_t len, loff_t *offp)
+{
+	struct seq_file *m = file->private_data;
+	struct drm_device *drm = m->private;
+	struct malidp_drm *malidp = drm->dev_private;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&malidp->errors_lock, irqflags);
+	malidp_error_stats_init(&malidp->de_errors);
+	malidp_error_stats_init(&malidp->se_errors);
+	spin_unlock_irqrestore(&malidp->errors_lock, irqflags);
+	return len;
+}
+
+static const struct file_operations malidp_debugfs_fops = {
+	.owner = THIS_MODULE,
+	.open = malidp_debugfs_open,
+	.read = seq_read,
+	.write = malidp_debugfs_write,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int malidp_debugfs_init(struct drm_minor *minor)
+{
+	struct malidp_drm *malidp = minor->dev->dev_private;
+	struct dentry *dentry = NULL;
+
+	malidp_error_stats_init(&malidp->de_errors);
+	malidp_error_stats_init(&malidp->se_errors);
+	spin_lock_init(&malidp->errors_lock);
+	dentry = debugfs_create_file("debug",
+				     S_IRUGO | S_IWUSR,
+				     minor->debugfs_root, minor->dev,
+				     &malidp_debugfs_fops);
+	if (!dentry) {
+		DRM_ERROR("Cannot create debug file\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+#endif //CONFIG_DEBUG_FS
+
 static struct drm_driver malidp_driver = {
 	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC |
 			   DRIVER_PRIME,
@@ -360,6 +461,9 @@ static struct drm_driver malidp_driver = {
 	.gem_prime_vmap = drm_gem_cma_prime_vmap,
 	.gem_prime_vunmap = drm_gem_cma_prime_vunmap,
 	.gem_prime_mmap = drm_gem_cma_prime_mmap,
+#ifdef CONFIG_DEBUG_FS
+	.debugfs_init = malidp_debugfs_init,
+#endif
 	.fops = &fops,
 	.name = "mali-dp",
 	.desc = "ARM Mali Display Processor driver",

drivers/gpu/drm/arm/malidp_drv.h

@@ -17,6 +17,7 @@
 #include <drm/drm_encoder.h>
 #include <linux/mutex.h>
 #include <linux/wait.h>
+#include <linux/spinlock.h>
 #include <drm/drmP.h>
 #include "malidp_hw.h"
 
@@ -24,6 +25,12 @@
 #define MALIDP_CONFIG_VALID_DONE	1
 #define MALIDP_CONFIG_START		0xd0
 
+struct malidp_error_stats {
+	s32 num_errors;
+	u32 last_error_status;
+	s64 last_error_vblank;
+};
+
 struct malidp_drm {
 	struct malidp_hw_device *dev;
 	struct drm_crtc crtc;
@@ -32,6 +39,12 @@ struct malidp_drm {
 	struct drm_pending_vblank_event *event;
 	atomic_t config_valid;
 	u32 core_id;
+#ifdef CONFIG_DEBUG_FS
+	struct malidp_error_stats de_errors;
+	struct malidp_error_stats se_errors;
+	/* Protects errors stats */
+	spinlock_t errors_lock;
+#endif
 };
 
 #define crtc_to_malidp_device(x) container_of(x, struct malidp_drm, crtc)
@@ -69,6 +82,12 @@ struct malidp_crtc_state {
 int malidp_de_planes_init(struct drm_device *drm);
 int malidp_crtc_init(struct drm_device *drm);
 
+#ifdef CONFIG_DEBUG_FS
+void malidp_error(struct malidp_drm *malidp,
+		  struct malidp_error_stats *error_stats, u32 status,
+		  u64 vblank);
+#endif
+
 /* often used combination of rotational bits */
 #define MALIDP_ROTATED_MASK	(DRM_MODE_ROTATE_90 | DRM_MODE_ROTATE_270)
 

drivers/gpu/drm/arm/malidp_hw.c

@@ -741,12 +741,18 @@ const struct malidp_hw malidp_device[MALIDP_MAX_DEVICES] = {
 					    MALIDP500_DE_IRQ_VSYNC |
 					    MALIDP500_DE_IRQ_GLOBAL,
 				.vsync_irq = MALIDP500_DE_IRQ_VSYNC,
+				.err_mask = MALIDP_DE_IRQ_UNDERRUN |
+					    MALIDP500_DE_IRQ_AXI_ERR |
+					    MALIDP500_DE_IRQ_SATURATION,
 			},
 			.se_irq_map = {
 				.irq_mask = MALIDP500_SE_IRQ_CONF_MODE |
 					    MALIDP500_SE_IRQ_CONF_VALID |
 					    MALIDP500_SE_IRQ_GLOBAL,
 				.vsync_irq = MALIDP500_SE_IRQ_CONF_VALID,
+				.err_mask = MALIDP500_SE_IRQ_INIT_BUSY |
+					    MALIDP500_SE_IRQ_AXI_ERROR |
+					    MALIDP500_SE_IRQ_OVERRUN,
 			},
 			.dc_irq_map = {
 				.irq_mask = MALIDP500_DE_IRQ_CONF_VALID,
@@ -782,11 +788,16 @@ const struct malidp_hw malidp_device[MALIDP_MAX_DEVICES] = {
 				.irq_mask = MALIDP_DE_IRQ_UNDERRUN |
 					    MALIDP550_DE_IRQ_VSYNC,
 				.vsync_irq = MALIDP550_DE_IRQ_VSYNC,
+				.err_mask = MALIDP_DE_IRQ_UNDERRUN |
+					    MALIDP550_DE_IRQ_SATURATION |
+					    MALIDP550_DE_IRQ_AXI_ERR,
 			},
 			.se_irq_map = {
-				.irq_mask = MALIDP550_SE_IRQ_EOW |
-					    MALIDP550_SE_IRQ_AXI_ERR,
+				.irq_mask = MALIDP550_SE_IRQ_EOW,
 				.vsync_irq = MALIDP550_SE_IRQ_EOW,
+				.err_mask  = MALIDP550_SE_IRQ_AXI_ERR |
+					     MALIDP550_SE_IRQ_OVR |
+					     MALIDP550_SE_IRQ_IBSY,
 			},
 			.dc_irq_map = {
 				.irq_mask = MALIDP550_DC_IRQ_CONF_VALID |
@@ -824,11 +835,21 @@ const struct malidp_hw malidp_device[MALIDP_MAX_DEVICES] = {
 					    MALIDP650_DE_IRQ_DRIFT |
 					    MALIDP550_DE_IRQ_VSYNC,
 				.vsync_irq = MALIDP550_DE_IRQ_VSYNC,
+				.err_mask = MALIDP_DE_IRQ_UNDERRUN |
+					    MALIDP650_DE_IRQ_DRIFT |
+					    MALIDP550_DE_IRQ_SATURATION |
+					    MALIDP550_DE_IRQ_AXI_ERR |
+					    MALIDP650_DE_IRQ_ACEV1 |
+					    MALIDP650_DE_IRQ_ACEV2 |
+					    MALIDP650_DE_IRQ_ACEG |
+					    MALIDP650_DE_IRQ_AXIEP,
 			},
 			.se_irq_map = {
-				.irq_mask = MALIDP550_SE_IRQ_EOW |
-					    MALIDP550_SE_IRQ_AXI_ERR,
+				.irq_mask = MALIDP550_SE_IRQ_EOW,
 				.vsync_irq = MALIDP550_SE_IRQ_EOW,
+				.err_mask = MALIDP550_SE_IRQ_AXI_ERR |
+					    MALIDP550_SE_IRQ_OVR |
+					    MALIDP550_SE_IRQ_IBSY,
 			},
 			.dc_irq_map = {
 				.irq_mask = MALIDP550_DC_IRQ_CONF_VALID |
@@ -920,10 +941,17 @@ static irqreturn_t malidp_de_irq(int irq, void *arg)
 		return ret;
 
 	mask = malidp_hw_read(hwdev, MALIDP_REG_MASKIRQ);
-	status &= mask;
+	/* keep the status of the enabled interrupts, plus the error bits */
+	status &= (mask | de->err_mask);
 	if ((status & de->vsync_irq) && malidp->crtc.enabled)
 		drm_crtc_handle_vblank(&malidp->crtc);
 
+#ifdef CONFIG_DEBUG_FS
+	if (status & de->err_mask) {
+		malidp_error(malidp, &malidp->de_errors, status,
+			     drm_crtc_vblank_count(&malidp->crtc));
+	}
+#endif
 	malidp_hw_clear_irq(hwdev, MALIDP_DE_BLOCK, status);
 
 	return (ret == IRQ_NONE) ? IRQ_HANDLED : ret;
@@ -999,11 +1027,15 @@ static irqreturn_t malidp_se_irq(int irq, void *arg)
 		return IRQ_NONE;
 
 	status = malidp_hw_read(hwdev, hw->map.se_base + MALIDP_REG_STATUS);
-	if (!(status & se->irq_mask))
+	if (!(status & (se->irq_mask | se->err_mask)))
 		return IRQ_NONE;
 
+#ifdef CONFIG_DEBUG_FS
+	if (status & se->err_mask)
+		malidp_error(malidp, &malidp->se_errors, status,
+			     drm_crtc_vblank_count(&malidp->crtc));
+#endif
 	mask = malidp_hw_read(hwdev, hw->map.se_base + MALIDP_REG_MASKIRQ);
-	status = malidp_hw_read(hwdev, hw->map.se_base + MALIDP_REG_STATUS);
 	status &= mask;
 
 	if (status & se->vsync_irq) {

drivers/gpu/drm/arm/malidp_hw.h

@@ -53,6 +53,7 @@ struct malidp_format_id {
 struct malidp_irq_map {
 	u32 irq_mask;		/* mask of IRQs that can be enabled in the block */
 	u32 vsync_irq;		/* IRQ bit used for signaling during VSYNC */
+	u32 err_mask;		/* mask of bits that represent errors */
 };
 
 struct malidp_layer {

drivers/gpu/drm/arm/malidp_regs.h

@@ -53,6 +53,8 @@
 #define MALIDP550_DE_IRQ_AXI_ERR		(1 << 16)
 #define MALIDP550_SE_IRQ_EOW			(1 << 0)
 #define MALIDP550_SE_IRQ_AXI_ERR		(1 << 16)
+#define MALIDP550_SE_IRQ_OVR			(1 << 17)
+#define MALIDP550_SE_IRQ_IBSY			(1 << 18)
 #define MALIDP550_DC_IRQ_CONF_VALID		(1 << 0)
 #define MALIDP550_DC_IRQ_CONF_MODE		(1 << 4)
 #define MALIDP550_DC_IRQ_CONF_ACTIVE		(1 << 16)
@@ -60,6 +62,10 @@
 #define MALIDP550_DC_IRQ_SE			(1 << 24)
 
 #define MALIDP650_DE_IRQ_DRIFT			(1 << 4)
+#define MALIDP650_DE_IRQ_ACEV1			(1 << 17)
+#define MALIDP650_DE_IRQ_ACEV2			(1 << 18)
+#define MALIDP650_DE_IRQ_ACEG			(1 << 19)
+#define MALIDP650_DE_IRQ_AXIEP			(1 << 28)
 
 /* bit masks that are common between products */
 #define   MALIDP_CFG_VALID		(1 << 0)