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.

In order for the tests to still pass, some extra checks are needed, so
it's not a 1:1 move.

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Tested-by: Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v9-9-24b168e5bcd5@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 5d4ac79381c49a95dac9be8fa2a3b2cb57454341..757a5dbb3cab89a4d6d53a20c8690382abe17bbe 100644 (file)
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1755,6 +1755,51 @@ 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 (name_end == 1 &&
+           (name[0] == 'd' || name[0] == 'D' || name[0] == 'e'))
+               return 0;
+
+       /*
+        * We're sure we're a named mode at this 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
@@ -1791,7 +1836,7 @@ 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;
@@ -1832,18 +1877,19 @@ 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 */
+       if (!mode_end)
+               return false;
 
-                       strcpy(mode->name, drm_named_modes_whitelist[i]);
-                       mode->specified = true;
-                       break;
-               }
-       }
+       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 */
        if (!mode->specified && isdigit(name[0])) {