[v2,4/5] drm/modes: Add support for driver-specific named modes

Commit Message

Geert Uytterhoeven July 14, 2022, 9:04 a.m. UTC

The mode parsing code recognizes named modes only if they are explicitly
listed in the internal whitelist, which is currently limited to "NTSC"
and "PAL".

Provide a mechanism for drivers to override this list to support custom
mode names.

Ideally, this list should just come from the driver's actual list of
modes, but connector->probed_modes is not yet populated at the time of
parsing.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
---
v2:
  - Add Reviewed-by.
---
 drivers/gpu/drm/drm_modes.c | 15 +++++++++++----
 include/drm/drm_connector.h | 10 ++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

Comments

Maxime Ripard July 14, 2022, 12:10 p.m. UTC | #1

On Thu, Jul 14, 2022 at 11:04:09AM +0200, Geert Uytterhoeven wrote:
> The mode parsing code recognizes named modes only if they are explicitly
> listed in the internal whitelist, which is currently limited to "NTSC"
> and "PAL".
> 
> Provide a mechanism for drivers to override this list to support custom
> mode names.
> 
> Ideally, this list should just come from the driver's actual list of
> modes, but connector->probed_modes is not yet populated at the time of
> parsing.
> 
> Signed-off-by: Geert Uytterhoeven <[e-mail]>
> Reviewed-by: Hans de Goede <[e-mail]>

Like we discussed on IRC, I'm not sure allowing drivers to handle named
modes is the right thing to do.

Named modes in general were a workaround the fact that we were missing
infos in drm_display_mode to describe all the modes.

I think we really should focus on addressing that first, and then
creating some kind of backward compat layer to create an initial DRM
state from a named mode provided on the command line.

Maxime

Patch

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 0cbf0467f263b30a..bfc3a08614522689 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1748,24 +1748,30 @@  static int drm_mode_parse_cmdline_options(const char *str,
 static const char * const drm_named_modes_whitelist[] = {
 	"NTSC",
 	"PAL",
+	NULL
 };
 
 static int drm_mode_parse_cmdline_named_mode(const char *name,
 					     unsigned int length, bool refresh,
+					     const struct drm_connector *connector,
 					     struct drm_cmdline_mode *mode)
 {
+	const char * const *named_modes_whitelist;
 	unsigned int i;
 	int ret;
 
-	for (i = 0; i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
-		ret = str_has_prefix(name, drm_named_modes_whitelist[i]);
+	named_modes_whitelist = connector->named_modes_whitelist ? :
+				drm_named_modes_whitelist;
+
+	for (i = 0; named_modes_whitelist[i]; i++) {
+		ret = str_has_prefix(name, named_modes_whitelist[i]);
 		if (ret != length)
 			continue;
 
 		if (refresh)
 			return -EINVAL; /* named + refresh is invalid */
 
-		strcpy(mode->name, drm_named_modes_whitelist[i]);
+		strcpy(mode->name, named_modes_whitelist[i]);
 		mode->specified = true;
 		return 0;
 	}
@@ -1849,7 +1855,8 @@  bool drm_mode_parse_command_line_for_connector(const char *mode_option,
 	/* First check for a named mode */
 	if (mode_end) {
 		ret = drm_mode_parse_cmdline_named_mode(name, mode_end,
-							refresh_ptr, mode);
+							refresh_ptr, connector,
+							mode);
 		if (ret)
 			return false;
 	}
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 3ac4bf87f2571c4c..6361f8a596c01107 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1659,6 +1659,16 @@  struct drm_connector {
 
 	/** @hdr_sink_metadata: HDR Metadata Information read from sink */
 	struct hdr_sink_metadata hdr_sink_metadata;
+
+	/**
+	 * @named_modes_whitelist:
+	 *
+	 * Optional NULL-terminated array of names to be considered valid mode
+	 * names.  This lets the command line option parser distinguish between
+	 * mode names and freestanding extras and/or options.
+	 * If not set, a set of defaults will be used.
+	 */
+	const char * const *named_modes_whitelist;
 };
 
 #define obj_to_connector(x) container_of(x, struct drm_connector, base)