[PATCHv2] modesetting: Add common widescreen resolutions

[Adel Gadllah]

Stolen from the intel ddx driver, see:
https://cgit.freedesktop.org/xorg/driver/xf86-video-intel/commit/?id=26fd6bec
https://bugs.freedesktop.org/show_bug.cgi?id=37858

it makes those common modes selectable when using the modesetting driver.

Signed-off-by: Adel Gadllah <adel.gadllah at gmail.com>
---
 hw/xfree86/drivers/modesetting/drmmode_display.c | 107 ++++++++++++++++++++++-
 1 file changed, 106 insertions(+), 1 deletion(-)

diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
index 0d34ca1..4faabcd 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -953,6 +953,111 @@ has_panel_fitter(xf86OutputPtr output)
     return FALSE;
 }
 
+static struct pixel_count {
+	int16_t width, height;
+} common_16_9[] = {
+	{ 640, 360 },
+	{ 720, 405 },
+	{ 864, 486 },
+	{ 960, 540 },
+	{ 1024, 576 },
+	{ 1280, 720 },
+	{ 1366, 768 },
+	{ 1600, 900 },
+	{ 1920, 1080 },
+	{ 2048, 1152 },
+	{ 2560, 1440 },
+	{ 2880, 1620 },
+	{ 3200, 1800 },
+	{ 3840, 2160 },
+	{ 4096, 2304 },
+	{ 5120, 2880 },
+	{ 7680, 4320 },
+	{ 15360, 8640 },
+}, common_16_10[] = {
+	{ 1280, 800 },
+	{ 1400, 900 },
+	{ 1680, 1050 },
+	{ 1920, 1200 },
+	{ 2560, 1600 },
+};
+
+static bool
+drmmode_output_is_duplicate_mode(DisplayModePtr modes, DisplayModePtr m)
+{
+	if (m == NULL)
+		return false;
+
+	while (modes) {
+		if (xf86ModesEqual(modes, m))
+			return true;
+
+		modes = modes->next;
+	}
+
+	return false;
+}
+
+static DisplayModePtr
+drmmode_output_get_default_modes(DisplayModePtr preferred)
+{
+    DisplayModePtr modes;
+    int n;
+
+    modes = xf86GetDefaultModes();
+    if (preferred) {
+		DisplayModePtr m;
+
+		/* Add a half-resolution mode useful for large panels */
+		m = xf86GTFMode(preferred->HDisplay / 2,
+				preferred->VDisplay / 2,
+				xf86ModeVRefresh(preferred),
+				FALSE, FALSE);
+		if (!drmmode_output_is_duplicate_mode(modes, m))
+			modes = xf86ModesAdd(modes, m);
+		else
+			free(m);
+
+		if (preferred->VDisplay * 16 > preferred->HDisplay * 9 - preferred->HDisplay / 32 &&
+		    preferred->VDisplay * 16 < preferred->HDisplay * 9 + preferred->HDisplay / 32) {
+			for (n = 0; n < ARRAY_SIZE(common_16_9); n++) {
+				if (preferred->HDisplay <= common_16_9[n].width ||
+				    preferred->VDisplay <= common_16_9[n].height)
+					break;
+
+				m = xf86GTFMode(common_16_9[n].width,
+						common_16_9[n].height,
+						xf86ModeVRefresh(preferred),
+						FALSE, FALSE);
+				if (!drmmode_output_is_duplicate_mode(modes, m))
+					modes = xf86ModesAdd(modes, m);
+				else
+					free(m);
+			}
+		}
+
+		if (preferred->VDisplay * 16 > preferred->HDisplay * 10 - preferred->HDisplay / 32 &&
+		    preferred->VDisplay * 16 < preferred->HDisplay * 10 + preferred->HDisplay / 32) {
+			for (n = 0; n < ARRAY_SIZE(common_16_10); n++) {
+				if (preferred->HDisplay <= common_16_10[n].width ||
+				    preferred->VDisplay <= common_16_10[n].height)
+					break;
+
+				m = xf86GTFMode(common_16_10[n].width,
+						common_16_10[n].height,
+						xf86ModeVRefresh(preferred),
+						FALSE, FALSE);
+				if (!drmmode_output_is_duplicate_mode(modes, m))
+					modes = xf86ModesAdd(modes, m);
+				else
+					free(m);
+			}
+		}
+	}
+
+	return modes;
+}
+
 static DisplayModePtr
 drmmode_output_add_gtf_modes(xf86OutputPtr output, DisplayModePtr Modes)
 {
@@ -978,7 +1083,7 @@ drmmode_output_add_gtf_modes(xf86OutputPtr output, DisplayModePtr Modes)
     max_vrefresh = max(max_vrefresh, 60.0);
     max_vrefresh *= (1 + SYNC_TOLERANCE);
 
-    m = xf86GetDefaultModes();
+    m = drmmode_output_get_default_modes(preferred);
     xf86ValidateModesSize(output->scrn, m, max_x, max_y, 0);
 
     for (i = m; i; i = i->next) {
-- 
2.5.0