linux-kernel - [PATCH v2 14/41] drm/modes: Move named modes parsing to a separate function

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Date:   Mon, 29 Aug 2022 15:11:28 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Maxime Ripard <mripard@...nel.org>,
        Ben Skeggs <bskeggs@...hat.com>,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Lyude Paul <lyude@...hat.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Karol Herbst <kherbst@...hat.com>,
        Noralf Trønnes <noralf@...nnes.org>,
        Emma Anholt <emma@...olt.net>, Daniel Vetter <daniel@...ll.ch>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Cc:     Maxime Ripard <maxime@...no.tech>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-arm-kernel@...ts.infradead.org,
        Phil Elwell <phil@...pberrypi.com>,
        intel-gfx@...ts.freedesktop.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        dri-devel@...ts.freedesktop.org, Dom Cobley <dom@...pberrypi.com>,
        linux-kernel@...r.kernel.org, nouveau@...ts.freedesktop.org,
        linux-sunxi@...ts.linux.dev,
        Mateusz Kwiatkowski <kfyatek+publicgit@...il.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH v2 14/41] drm/modes: Move named modes parsing to a separate function

The current construction of the named mode parsing doesn't allow to extend
it easily. Let's move it to a separate function so we can add more
parameters and modes.

Signed-off-by: Maxime Ripard <maxime@...no.tech>

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 99a21e5cd00d..0636cb707544 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1909,6 +1909,9 @@ void drm_connector_list_update(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_connector_list_update);
 
+#define STR_STRICT_EQ(str, len, cmp) \
+	((strlen(cmp) == len) && !strncmp(str, cmp, len))
+
 static int drm_mode_parse_cmdline_bpp(const char *str, char **end_ptr,
 				      struct drm_cmdline_mode *mode)
 {
@@ -2208,6 +2211,52 @@ static const char * const drm_named_modes_whitelist[] = {
 	"PAL",
 };
 
+static int drm_mode_parse_cmdline_named_mode(const char *name,
+					     unsigned int name_end,
+					     struct drm_cmdline_mode *cmdline_mode)
+{
+	unsigned int i;
+
+	if (!name_end)
+		return 0;
+
+	/* If the name starts with a digit, it's not a named mode */
+	if (isdigit(name[0]))
+		return 0;
+
+	/*
+	 * If there's an equal sign in the name, the command-line
+	 * contains only an option and no mode.
+	 */
+	if (strnchr(name, name_end, '='))
+		return 0;
+
+	/* The connection status extras can be set without a mode. */
+	if (STR_STRICT_EQ(name, name_end, "d") ||
+	    STR_STRICT_EQ(name, name_end, "D") ||
+	    STR_STRICT_EQ(name, name_end, "e"))
+		return 0;
+
+	/*
+	 * We're sure we're a named mode at that point, iterate over the
+	 * list of modes we're aware of.
+	 */
+	for (i = 0; i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
+		int ret;
+
+		ret = str_has_prefix(name, drm_named_modes_whitelist[i]);
+		if (ret != name_end)
+			continue;
+
+		strcpy(cmdline_mode->name, drm_named_modes_whitelist[i]);
+		cmdline_mode->specified = true;
+
+		return 1;
+	}
+
+	return -EINVAL;
+}
+
 /**
  * drm_mode_parse_command_line_for_connector - parse command line modeline for connector
  * @mode_option: optional per connector mode option
@@ -2244,7 +2293,7 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
 	const char *bpp_ptr = NULL, *refresh_ptr = NULL, *extra_ptr = NULL;
 	const char *options_ptr = NULL;
 	char *bpp_end_ptr = NULL, *refresh_end_ptr = NULL;
-	int i, len, ret;
+	int len, ret;
 
 	memset(mode, 0, sizeof(*mode));
 	mode->panel_orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
@@ -2285,17 +2334,19 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
 		parse_extras = true;
 	}
 
-	/* First check for a named mode */
-	for (i = 0; i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
-		ret = str_has_prefix(name, drm_named_modes_whitelist[i]);
-		if (ret == mode_end) {
-			if (refresh_ptr)
-				return false; /* named + refresh is invalid */
 
-			strcpy(mode->name, drm_named_modes_whitelist[i]);
-			mode->specified = true;
-			break;
-		}
+	if (mode_end) {
+		ret = drm_mode_parse_cmdline_named_mode(name, mode_end, mode);
+		if (ret < 0)
+			return false;
+
+		/*
+		 * Having a mode that starts by a letter (and thus is named)
+		 * and an at-sign (used to specify a refresh rate) is
+		 * disallowed.
+		 */
+		if (ret && refresh_ptr)
+			return false;
 	}
 
 	/* No named mode? Check for a normal mode argument, e.g. 1024x768 */

-- 
b4 0.10.0-dev-65ba7