backends/drm: query min and max values for properties

src/backends/drm/drm_property.cpp

@@ -30,6 +30,11 @@ DrmProperty::DrmProperty(DrmObject *obj, drmModePropertyRes *prop, uint64_t val,
         m_enumNames = enumNames;
         initEnumMap(prop);
     }
+    if (prop->flags & DRM_MODE_PROP_RANGE) {
+        Q_ASSERT(prop->count_values > 1);
+        m_minValue = prop->values[0];
+        m_maxValue = prop->values[1];
+    }
 }
 
 DrmProperty::~DrmProperty() = default;
@@ -146,4 +151,14 @@ void DrmProperty::setLegacy()
     m_legacy = true;
 }
 
+uint64_t DrmProperty::minValue() const
+{
+    return m_minValue;
+}
+
+uint64_t DrmProperty::maxValue() const
+{
+    return m_maxValue;
+}
+
 }

src/backends/drm/drm_property.h

@@ -60,6 +60,9 @@ public:
     void setCurrent(uint64_t value);
     uint64_t current() const;
 
+    uint64_t minValue() const;
+    uint64_t maxValue() const;
+
     void commit();
     void commitPending();
     void rollbackPending();
@@ -87,6 +90,9 @@ private:
     // the value currently set for or by the kernel
     uint64_t m_current = 0;
 
+    uint64_t m_minValue = -1;
+    uint64_t m_maxValue = -1;
+
     QMap<uint32_t, uint64_t> m_enumMap;
     QVector<QByteArray> m_enumNames;
     const bool m_immutable;