[plasma/kwin] src/backends/drm: backends/drm: filter out unusably small modes

Git commit a64249da3c9ae470439ba09766e38a47d84ecb91 by Xaver Hugl.
Committed on 17/08/2026 at 15:53.
Pushed by zamundaaa into branch 'master'.

backends/drm: filter out unusably small modes

If a user accidentally selects a mode like 320x240, they will have a
very hard time using system settings to get back to a usable mode.
To avoid that, this simply filters out all modes smaller than 480p,
unless all modes are that small.

M  +13   -2    src/backends/drm/drm_connector.cpp

https://invent.kde.org/plasma/kwin/-/commit/a64249da3c9ae470439ba09766e38a47d84ecb91

diff --git a/src/backends/drm/drm_connector.cpp b/src/backends/drm/drm_connector.cpp
index 5c7122e135b..12b484d9e68 100644
--- a/src/backends/drm/drm_connector.cpp
+++ b/src/backends/drm/drm_connector.cpp
@@ -327,8 +327,19 @@ bool DrmConnector::updateProperties()
     if (!equal && m_conn->count_modes > 0) {
         // reload modes
         m_driverModes.clear();
-        for (int i = 0; i < m_conn->count_modes; i++) {
-            m_driverModes.append(std::make_shared<DrmConnectorMode>(this, m_conn->modes[i]));
+        const auto modes = std::span(m_conn->modes, m_conn->count_modes);
+        auto usableModes = modes | std::views::filter([](drmModeModeInfo mode) {
+            return mode.hdisplay >= 640 && mode.vdisplay >= 480;
+        });
+        if (usableModes.empty()) {
+            // allow unusable modes, we don't have much of a choice
+            for (const auto &mode : modes) {
+                m_driverModes.append(std::make_shared<DrmConnectorMode>(this, mode));
+            }
+        } else {
+            for (const auto &mode : usableModes) {
+                m_driverModes.append(std::make_shared<DrmConnectorMode>(this, mode));
+            }
         }
         m_modes.clear();
         m_modes.append(m_driverModes);