drm: Take vt(4) default mode from loader tunables

By default, vt(4) gets the "preferred mode" from DRM, when using a DRM
video driver as its backend. The preferred mode is usually the native
screen resolution.

Now, if this mode isn't appropriate, a user can use loader tunables to
select a mode. The tunables are read in the following order:
    1. kern.vt.fb.modes.$connector_name
    2. kern.vt.fb.default_mode

For example, to set a 1024x768 mode, no matter the connector:
    kern.vt.fb.default_mode="1024x768"

To set a 800x600 mode only on the laptop builtin screen:
    kern.vt.fb.modes.LVDS-1="800x600"

Beside r274031, this MFC includes:

r274049:
  drm: When reading connector mode tunables, list connectors

  ... and their associated tunables. This gives a way to know the list of
  available connectors, no matter the driver.

  The problem is that xrandr(1) can list connectors but it uses a
  different naming.

r274050:
  vt(4): Document kern.vt.fb.default_mode and kern.vt.fb.modes.*

  Those tunables are used to set a specific mode in vt(4) instead of using
  the default mode.

  Differential Revision:	https://reviews.freebsd.org/D1098
  Reviewed by:	ak@, emaste@, kwm@

r274051:
  vt(4): Improve the description of kern.vt.fb.modes.$connector

  Differential Revision:	https://reviews.freebsd.org/D1098
  Submitted by:	emaste@

r274053:
  vt(4): Start new sentences on their own lines

  Submitted by:	brueffer@

MFC of:		r274031, r274049, r274050, r274051, r274053

2 files changed, 68 insertions, 182 deletions

diff --git a/sys/dev/drm2/drm_fb_helper.c b/sys/dev/drm2/drm_fb_helper.c
index 05f616e..20ee3fb 100644
--- a/sys/dev/drm2/drm_fb_helper.c
+++ b/sys/dev/drm2/drm_fb_helper.c
@@ -38,6 +38,8 @@ __FBSDID("$FreeBSD$");
 
 
 #include <sys/kdb.h>
+#include <sys/param.h>
+#include <sys/systm.h>
 
 struct vt_kms_softc {
 	struct drm_fb_helper *fb_helper;
@@ -97,170 +99,34 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
 	return 0;
 }
 
-const char *fb_mode_option;
-
-/**
- * drm_fb_helper_connector_parse_command_line - parse command line for connector
- * @connector - connector to parse line for
- * @mode_option - per connector mode option
- *
- * This parses the connector specific then generic command lines for
- * modes and options to configure the connector.
- *
- * This uses the same parameters as the fb modedb.c, except for extra
- *	<xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m][eDd]
- *
- * enable/enable Digital/disable bit at the end
- */
-static bool drm_fb_helper_connector_parse_command_line(struct drm_fb_helper_connector *fb_helper_conn,
-						       const char *mode_option)
-{
-	const char *name;
-	unsigned int namelen;
-	int res_specified = 0, bpp_specified = 0, refresh_specified = 0;
-	unsigned int xres = 0, yres = 0, bpp = 32, refresh = 0;
-	int yres_specified = 0, cvt = 0, rb = 0, interlace = 0, margins = 0;
-	int i;
-	enum drm_connector_force force = DRM_FORCE_UNSPECIFIED;
-	struct drm_fb_helper_cmdline_mode *cmdline_mode;
-	struct drm_connector *connector;
-
-	if (!fb_helper_conn)
-		return false;
-	connector = fb_helper_conn->connector;
-
-	cmdline_mode = &fb_helper_conn->cmdline_mode;
-	if (!mode_option)
-		mode_option = fb_mode_option;
-
-	if (!mode_option) {
-		cmdline_mode->specified = false;
-		return false;
-	}
-
-	name = mode_option;
-	namelen = strlen(name);
-	for (i = namelen-1; i >= 0; i--) {
-		switch (name[i]) {
-		case '@':
-			namelen = i;
-			if (!refresh_specified && !bpp_specified &&
-			    !yres_specified) {
-				refresh = strtol(&name[i+1], NULL, 10);
-				refresh_specified = 1;
-				if (cvt || rb)
-					cvt = 0;
-			} else
-				goto done;
-			break;
-		case '-':
-			namelen = i;
-			if (!bpp_specified && !yres_specified) {
-				bpp = strtol(&name[i+1], NULL, 10);
-				bpp_specified = 1;
-				if (cvt || rb)
-					cvt = 0;
-			} else
-				goto done;
-			break;
-		case 'x':
-			if (!yres_specified) {
-				yres = strtol(&name[i+1], NULL, 10);
-				yres_specified = 1;
-			} else
-				goto done;
-		case '0' ... '9':
-			break;
-		case 'M':
-			if (!yres_specified)
-				cvt = 1;
-			break;
-		case 'R':
-			if (cvt)
-				rb = 1;
-			break;
-		case 'm':
-			if (!cvt)
-				margins = 1;
-			break;
-		case 'i':
-			if (!cvt)
-				interlace = 1;
-			break;
-		case 'e':
-			force = DRM_FORCE_ON;
-			break;
-		case 'D':
-			if ((connector->connector_type != DRM_MODE_CONNECTOR_DVII) &&
-			    (connector->connector_type != DRM_MODE_CONNECTOR_HDMIB))
-				force = DRM_FORCE_ON;
-			else
-				force = DRM_FORCE_ON_DIGITAL;
-			break;
-		case 'd':
-			force = DRM_FORCE_OFF;
-			break;
-		default:
-			goto done;
-		}
-	}
-	if (i < 0 && yres_specified) {
-		xres = strtol(name, NULL, 10);
-		res_specified = 1;
-	}
-done:
-
-	DRM_DEBUG_KMS("cmdline mode for connector %s %dx%d@%dHz%s%s%s\n",
-		drm_get_connector_name(connector), xres, yres,
-		(refresh) ? refresh : 60, (rb) ? " reduced blanking" :
-		"", (margins) ? " with margins" : "", (interlace) ?
-		" interlaced" : "");
-
-	if (force) {
-		const char *s;
-		switch (force) {
-		case DRM_FORCE_OFF: s = "OFF"; break;
-		case DRM_FORCE_ON_DIGITAL: s = "ON - dig"; break;
-		default:
-		case DRM_FORCE_ON: s = "ON"; break;
-		}
-
-		DRM_INFO("forcing %s connector %s\n",
-			 drm_get_connector_name(connector), s);
-		connector->force = force;
-	}
-
-	if (res_specified) {
-		cmdline_mode->specified = true;
-		cmdline_mode->xres = xres;
-		cmdline_mode->yres = yres;
-	}
-
-	if (refresh_specified) {
-		cmdline_mode->refresh_specified = true;
-		cmdline_mode->refresh = refresh;
-	}
-
-	if (bpp_specified) {
-		cmdline_mode->bpp_specified = true;
-		cmdline_mode->bpp = bpp;
-	}
-	cmdline_mode->rb = rb ? true : false;
-	cmdline_mode->cvt = cvt  ? true : false;
-	cmdline_mode->interlace = interlace ? true : false;
-
-	return true;
-}
-
 static int
 fb_get_options(const char *connector_name, char **option)
 {
+	char tunable[64];
 
 	/*
-	 * TODO: store mode options pointer in ${option} for connector with
-	 * name ${connector_name}
+	 * A user may use loader tunables to set a specific mode for the
+	 * console. Tunables are read in the following order:
+	 *     1. kern.vt.fb.modes.$connector_name
+	 *     2. kern.vt.fb.default_mode
+	 *
+	 * Example of a mode specific to the LVDS connector:
+	 *     kern.vt.fb.modes.LVDS="1024x768"
+	 *
+	 * Example of a mode applied to all connectors not having a
+	 * connector-specific mode:
+	 *     kern.vt.fb.default_mode="640x480"
 	 */
-	return (1);
+	snprintf(tunable, sizeof(tunable), "kern.vt.fb.modes.%s",
+	    connector_name);
+	DRM_INFO("Connector %s: get mode from tunables:\n", connector_name);
+	DRM_INFO("  - %s\n", tunable);
+	DRM_INFO("  - kern.vt.fb.default_mode\n");
+	*option = getenv(tunable);
+	if (*option == NULL)
+		*option = getenv("kern.vt.fb.default_mode");
+
+	return (*option != NULL ? 0 : 1);
 }
 
 static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
@@ -269,15 +135,52 @@ static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
 	int i;
 
 	for (i = 0; i < fb_helper->connector_count; i++) {
+		struct drm_cmdline_mode *mode;
+		struct drm_connector *connector;
 		char *option = NULL;
 
 		fb_helper_conn = fb_helper->connector_info[i];
+		connector = fb_helper_conn->connector;
+		mode = &fb_helper_conn->cmdline_mode;
 
 		/* do something on return - turn off connector maybe */
-		if (fb_get_options(drm_get_connector_name(fb_helper_conn->connector), &option))
+		if (fb_get_options(drm_get_connector_name(connector), &option))
 			continue;
 
-		drm_fb_helper_connector_parse_command_line(fb_helper_conn, option);
+		if (drm_mode_parse_command_line_for_connector(option,
+							      connector,
+							      mode)) {
+			if (mode->force) {
+				const char *s;
+				switch (mode->force) {
+				case DRM_FORCE_OFF:
+					s = "OFF";
+					break;
+				case DRM_FORCE_ON_DIGITAL:
+					s = "ON - dig";
+					break;
+				default:
+				case DRM_FORCE_ON:
+					s = "ON";
+					break;
+				}
+
+				DRM_INFO("forcing %s connector %s\n",
+					 drm_get_connector_name(connector), s);
+				connector->force = mode->force;
+			}
+
+			DRM_INFO("cmdline mode for connector %s %dx%d@%dHz%s%s%s\n",
+				      drm_get_connector_name(connector),
+				      mode->xres, mode->yres,
+				      mode->refresh_specified ? mode->refresh : 60,
+				      mode->rb ? " reduced blanking" : "",
+				      mode->margins ? " with margins" : "",
+				      mode->interlace ?  " interlaced" : "");
+		}
+
+		freeenv(option);
+
 	}
 	return 0;
 }
@@ -956,7 +859,7 @@ int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 	/* first up get a count of crtcs now in use and new min/maxes width/heights */
 	for (i = 0; i < fb_helper->connector_count; i++) {
 		struct drm_fb_helper_connector *fb_helper_conn = fb_helper->connector_info[i];
-		struct drm_fb_helper_cmdline_mode *cmdline_mode;
+		struct drm_cmdline_mode *cmdline_mode;
 
 		cmdline_mode = &fb_helper_conn->cmdline_mode;
 
@@ -1181,7 +1084,7 @@ static struct drm_display_mode *drm_has_preferred_mode(struct drm_fb_helper_conn
 
 static bool drm_has_cmdline_mode(struct drm_fb_helper_connector *fb_connector)
 {
-	struct drm_fb_helper_cmdline_mode *cmdline_mode;
+	struct drm_cmdline_mode *cmdline_mode;
 	cmdline_mode = &fb_connector->cmdline_mode;
 	return cmdline_mode->specified;
 }
@@ -1192,10 +1095,8 @@ static struct drm_display_mode *drm_pick_cmdline_mode(struct drm_fb_helper_conne
 	struct drm_cmdline_mode *cmdline_mode;
 	struct drm_display_mode *mode = NULL;
 
-	cmdline_mode = &fb_helper_conn->cmdline_mode1;
-	if (cmdline_mode->specified == false &&
-	    !drm_fetch_cmdline_mode_from_kenv(fb_helper_conn->connector,
-	    cmdline_mode))
+	cmdline_mode = &fb_helper_conn->cmdline_mode;
+	if (cmdline_mode->specified == false)
 			return (NULL);
 
 	/* attempt to find a matching mode in the list of modes
diff --git a/sys/dev/drm2/drm_fb_helper.h b/sys/dev/drm2/drm_fb_helper.h
index 4b5ef85..16ef7ee 100644
--- a/sys/dev/drm2/drm_fb_helper.h
+++ b/sys/dev/drm2/drm_fb_helper.h
@@ -40,20 +40,6 @@ struct drm_fb_helper_crtc {
 	struct drm_display_mode *desired_mode;
 };
 
-/* mode specified on the command line */
-struct drm_fb_helper_cmdline_mode {
-	bool specified;
-	bool refresh_specified;
-	bool bpp_specified;
-	int xres, yres;
-	int bpp;
-	int refresh;
-	bool rb;
-	bool interlace;
-	bool cvt;
-	bool margins;
-};
-
 struct drm_fb_helper_surface_size {
 	u32 fb_width;
 	u32 fb_height;
@@ -74,9 +60,8 @@ struct drm_fb_helper_funcs {
 };
 
 struct drm_fb_helper_connector {
-	struct drm_fb_helper_cmdline_mode cmdline_mode;
-	struct drm_cmdline_mode cmdline_mode1;
 	struct drm_connector *connector;
+	struct drm_cmdline_mode cmdline_mode;
 };
 
 struct drm_fb_helper {