drm/komeda: Adds error event print functionality

Adds to print the event message when error happens and the same event
will not be printed until next vsync.

Changes since v2:
1. Refine komeda_sprintf();
2. Not using STR_SZ macro for the string size in komeda_print_events().

Changes since v1:
1. Handling the event print by CONFIG_KOMEDA_ERROR_PRINT;
2. Changing the max string size to 256.

Signed-off-by: Lowry Li (Arm Technology China) <[e-mail]>
Reviewed-by: Mihail Atanassov <[e-mail]>
Reviewed-by: James Qian Wang (Arm Technology China) <[e-mail]>
Signed-off-by: james qian wang (Arm Technology China) <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/arm/display/Kconfig

···
 	  Processor driver. It supports the D71 variants of the hardware.
 
 	  If compiled as a module it will be called komeda.
+
+config DRM_KOMEDA_ERROR_PRINT
+	bool "Enable komeda error print"
+	depends on DRM_KOMEDA
+	help
+	  Choose this option to enable error printing.

drivers/gpu/drm/arm/display/komeda/Makefile

···
 	d71/d71_dev.o \
 	d71/d71_component.o
 
+komeda-$(CONFIG_DRM_KOMEDA_ERROR_PRINT) += komeda_event.o
+
 obj-$(CONFIG_DRM_KOMEDA) += komeda.o

drivers/gpu/drm/arm/display/komeda/komeda_dev.h

···
 #define KOMEDA_ERR_TTNG			BIT_ULL(30)
 #define KOMEDA_ERR_TTF			BIT_ULL(31)
 
+#define KOMEDA_ERR_EVENTS	\
+	(KOMEDA_EVENT_URUN	| KOMEDA_EVENT_IBSY	| KOMEDA_EVENT_OVR |\
+	KOMEDA_ERR_TETO		| KOMEDA_ERR_TEMR	| KOMEDA_ERR_TITR |\
+	KOMEDA_ERR_CPE		| KOMEDA_ERR_CFGE	| KOMEDA_ERR_AXIE |\
+	KOMEDA_ERR_ACE0		| KOMEDA_ERR_ACE1	| KOMEDA_ERR_ACE2 |\
+	KOMEDA_ERR_ACE3		| KOMEDA_ERR_DRIFTTO	| KOMEDA_ERR_FRAMETO |\
+	KOMEDA_ERR_ZME		| KOMEDA_ERR_MERR	| KOMEDA_ERR_TCF |\
+	KOMEDA_ERR_TTNG		| KOMEDA_ERR_TTF)
+
+#define KOMEDA_WARN_EVENTS	KOMEDA_ERR_CSCE
+
 /* malidp device id */
 enum {
 	MALI_D71 = 0,
···
 void komeda_dev_destroy(struct komeda_dev *mdev);
 
 struct komeda_dev *dev_to_mdev(struct device *dev);
+
+#ifdef CONFIG_DRM_KOMEDA_ERROR_PRINT
+void komeda_print_events(struct komeda_events *evts);
+#endif
 
 #endif /*_KOMEDA_DEV_H_*/

drivers/gpu/drm/arm/display/komeda/komeda_event.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) COPYRIGHT 2019 ARM Limited. All rights reserved.
+ * Author: James.Qian.Wang <[e-mail]>
+ *
+ */
+#include <drm/drm_print.h>
+
+#include "komeda_dev.h"
+
+struct komeda_str {
+	char *str;
+	u32 sz;
+	u32 len;
+};
+
+/* return 0 on success,  < 0 on no space.
+ */
+static int komeda_sprintf(struct komeda_str *str, const char *fmt, ...)
+{
+	va_list args;
+	int num, free_sz;
+	int err;
+
+	free_sz = str->sz - str->len - 1;
+	if (free_sz <= 0)
+		return -ENOSPC;
+
+	va_start(args, fmt);
+
+	num = vsnprintf(str->str + str->len, free_sz, fmt, args);
+
+	va_end(args);
+
+	if (num < free_sz) {
+		str->len += num;
+		err = 0;
+	} else {
+		str->len = str->sz - 1;
+		err = -ENOSPC;
+	}
+
+	return err;
+}
+
+static void evt_sprintf(struct komeda_str *str, u64 evt, const char *msg)
+{
+	if (evt)
+		komeda_sprintf(str, msg);
+}
+
+static void evt_str(struct komeda_str *str, u64 events)
+{
+	if (events == 0ULL) {
+		komeda_sprintf(str, "None");
+		return;
+	}
+
+	evt_sprintf(str, events & KOMEDA_EVENT_VSYNC, "VSYNC|");
+	evt_sprintf(str, events & KOMEDA_EVENT_FLIP, "FLIP|");
+	evt_sprintf(str, events & KOMEDA_EVENT_EOW, "EOW|");
+	evt_sprintf(str, events & KOMEDA_EVENT_MODE, "OP-MODE|");
+
+	evt_sprintf(str, events & KOMEDA_EVENT_URUN, "UNDERRUN|");
+	evt_sprintf(str, events & KOMEDA_EVENT_OVR, "OVERRUN|");
+
+	/* GLB error */
+	evt_sprintf(str, events & KOMEDA_ERR_MERR, "MERR|");
+	evt_sprintf(str, events & KOMEDA_ERR_FRAMETO, "FRAMETO|");
+
+	/* DOU error */
+	evt_sprintf(str, events & KOMEDA_ERR_DRIFTTO, "DRIFTTO|");
+	evt_sprintf(str, events & KOMEDA_ERR_FRAMETO, "FRAMETO|");
+	evt_sprintf(str, events & KOMEDA_ERR_TETO, "TETO|");
+	evt_sprintf(str, events & KOMEDA_ERR_CSCE, "CSCE|");
+
+	/* LPU errors or events */
+	evt_sprintf(str, events & KOMEDA_EVENT_IBSY, "IBSY|");
+	evt_sprintf(str, events & KOMEDA_ERR_AXIE, "AXIE|");
+	evt_sprintf(str, events & KOMEDA_ERR_ACE0, "ACE0|");
+	evt_sprintf(str, events & KOMEDA_ERR_ACE1, "ACE1|");
+	evt_sprintf(str, events & KOMEDA_ERR_ACE2, "ACE2|");
+	evt_sprintf(str, events & KOMEDA_ERR_ACE3, "ACE3|");
+
+	/* LPU TBU errors*/
+	evt_sprintf(str, events & KOMEDA_ERR_TCF, "TCF|");
+	evt_sprintf(str, events & KOMEDA_ERR_TTNG, "TTNG|");
+	evt_sprintf(str, events & KOMEDA_ERR_TITR, "TITR|");
+	evt_sprintf(str, events & KOMEDA_ERR_TEMR, "TEMR|");
+	evt_sprintf(str, events & KOMEDA_ERR_TTF, "TTF|");
+
+	/* CU errors*/
+	evt_sprintf(str, events & KOMEDA_ERR_CPE, "COPROC|");
+	evt_sprintf(str, events & KOMEDA_ERR_ZME, "ZME|");
+	evt_sprintf(str, events & KOMEDA_ERR_CFGE, "CFGE|");
+	evt_sprintf(str, events & KOMEDA_ERR_TEMR, "TEMR|");
+
+	if (str->len > 0 && (str->str[str->len - 1] == '|')) {
+		str->str[str->len - 1] = 0;
+		str->len--;
+	}
+}
+
+static bool is_new_frame(struct komeda_events *a)
+{
+	return (a->pipes[0] | a->pipes[1]) &
+	       (KOMEDA_EVENT_FLIP | KOMEDA_EVENT_EOW);
+}
+
+void komeda_print_events(struct komeda_events *evts)
+{
+	u64 print_evts = KOMEDA_ERR_EVENTS;
+	static bool en_print = true;
+
+	/* reduce the same msg print, only print the first evt for one frame */
+	if (evts->global || is_new_frame(evts))
+		en_print = true;
+	if (!en_print)
+		return;
+
+	if ((evts->global | evts->pipes[0] | evts->pipes[1]) & print_evts) {
+		char msg[256];
+		struct komeda_str str;
+
+		str.str = msg;
+		str.sz  = sizeof(msg);
+		str.len = 0;
+
+		komeda_sprintf(&str, "gcu: ");
+		evt_str(&str, evts->global);
+		komeda_sprintf(&str, ", pipes[0]: ");
+		evt_str(&str, evts->pipes[0]);
+		komeda_sprintf(&str, ", pipes[1]: ");
+		evt_str(&str, evts->pipes[1]);
+
+		DRM_ERROR("err detect: %s\n", msg);
+
+		en_print = false;
+	}
+}

drivers/gpu/drm/arm/display/komeda/komeda_kms.c

···
 	memset(&evts, 0, sizeof(evts));
 	status = mdev->funcs->irq_handler(mdev, &evts);
 
+#ifdef CONFIG_DRM_KOMEDA_ERROR_PRINT
+	komeda_print_events(&evts);
+#endif
+
 	/* Notify the crtc to handle the events */
 	for (i = 0; i < kms->n_crtcs; i++)
 		komeda_crtc_handle_event(&kms->crtcs[i], &evts);