[i-g-t 1/2] lib/igt_kms: Add a helper function to check Bigjoiner support

[Bhanuprakash Modem]

Create a helper function to check that the system supports the
given crtc/connector mode(s).

Example:
* Pipe-D won't support Bigjoiner, hence we can't use the connector
  modes greater than 5K on Pipe-D
* To use 8K mode on a pipe, then the consecutive pipe must be free.

The Kernel is expected to reject the invalid combo (which must be
validated as a scenario separately). So, this helper function checks
the validity of the combo to avoid failures.

To use this helper, each individual subtest needs to set the @pipe
to a specific @output by igt_output_set_pipe() and call this helper
to check the validity of the combo.

V2:
* Rebase
* Add support to handle fused pipes

Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare at intel.com>
---
 lib/igt_kms.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  3 ++
 2 files changed, 83 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 36dfcfcb..74425db3 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -5636,3 +5636,83 @@ bool igt_check_output_bpc_equal(int drmfd, enum pipe pipe,
 
 	return (current == bpc);
 }
+
+static enum pipe find_pipe_index(const enum pipe pipe_seq[], enum pipe value)
+{
+	enum pipe index = PIPE_A;
+
+	while (index < IGT_MAX_PIPES && pipe_seq[index] != value)
+		index++;
+
+	return (index == IGT_MAX_PIPES) ? PIPE_NONE : index;
+}
+
+/*
+ * igt_check_bigjoiner_support:
+ * @display: a pointer to an #igt_display_t structure
+ *
+ * Get all active pipes from connected outputs (i.e. pending_pipe != PIPE_NONE)
+ * and check those pipes supports the selected mode(s).
+ *
+ * Example:
+ *  * Pipe-D can't support mode > 5K
+ *  * To use 8K mode on a pipe then consecutive pipe must be free.
+ *
+ * Returns: true if a valid crtc/connector mode combo found, else false
+ */
+bool igt_check_bigjoiner_support(igt_display_t *display)
+{
+	uint8_t i, total_pipes = 0, pipes_in_use = 0;
+	enum pipe p, pipe_seq[IGT_MAX_PIPES];
+	struct {
+		enum pipe idx;
+		drmModeModeInfo *mode;
+	} pipes[IGT_MAX_PIPES];
+
+	/* Get total enabled pipes. */
+	for_each_pipe(display, p) {
+		pipe_seq[total_pipes] = p;
+		total_pipes++;
+	}
+
+	/*
+	 * Get list of pipes in use those were set by igt_output_set_pipe()
+	 * just before calling this function.
+	 */
+	for (i = 0 ; i < display->n_outputs; i++) {
+		igt_output_t *output = &display->outputs[i];
+
+		if (output->pending_pipe == PIPE_NONE)
+			continue;
+
+		pipes[pipes_in_use].idx = find_pipe_index(pipe_seq, output->pending_pipe);
+		pipes[pipes_in_use].mode = igt_output_get_mode(output);
+		pipes_in_use++;
+	}
+
+	if (!pipes_in_use)
+		igt_skip("We must set atleast one output to pipe.\n");
+
+	/*
+	 * if mode.hdisplay > 5120, then ignore
+	 *  - last crtc in single/multi-connector config
+	 *  - consecutive crtcs in multi-connector config
+	 *
+	 * in multi-connector config ignore if
+	 *  - previous crtc mode.hdisplay > 5120 and
+	 *  - current & previous crtcs are consecutive
+	 */
+	for (i = 0; i < pipes_in_use; i++) {
+		if (((pipes[i].mode->hdisplay > MAX_HDISPLAY_PER_PIPE) &&
+		     ((pipes[i].idx >= (total_pipes - 1)) ||
+		      ((i < (pipes_in_use - 1)) && (abs(pipes[i + 1].idx - pipes[i].idx) <= 1)))) ||
+		    ((i > 0) && (pipes[i - 1].mode->hdisplay > MAX_HDISPLAY_PER_PIPE) &&
+		     (abs(pipes[i].idx - pipes[i - 1].idx) <= 1))) {
+			igt_debug("Pipe/Output combo is not possible with selected mode(s).\n");
+
+			return false;
+		}
+	}
+
+	return true;
+}
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index 0f12d825..3e674e74 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -109,6 +109,7 @@ const char *kmstest_connector_status_str(int status);
 const char *kmstest_connector_type_str(int type);
 
 void kmstest_dump_mode(drmModeModeInfo *mode);
+#define MAX_HDISPLAY_PER_PIPE 5120
 
 int kmstest_get_pipe_from_crtc_id(int fd, int crtc_id);
 void kmstest_set_vt_graphics_mode(void);
@@ -967,4 +968,6 @@ int sort_drm_modes_by_res_asc(const void *a, const void *b);
 void igt_sort_connector_modes(drmModeConnector *connector,
 		int (*comparator)(const void *, const void*));
 
+bool igt_check_bigjoiner_support(igt_display_t *display);
+
 #endif /* __IGT_KMS_H__ */
-- 
2.35.1