From 64ec76f5a67ddc836d3d49d7800d27ce7eb20d06 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E9=80=9A=E6=B4=B2?= <zhangsongcui3371@sina.com>
Date: Thu, 18 Apr 2024 09:52:55 +0800
Subject: [PATCH] Display (Linux): detect refresh rate for DRM method

---
 src/detection/displayserver/linux/drm.c | 61 ++++++++++++-------------
 src/util/edidHelper.c                   | 19 ++++++++
 src/util/edidHelper.h                   |  1 +
 3 files changed, 49 insertions(+), 32 deletions(-)

diff --git a/src/detection/displayserver/linux/drm.c b/src/detection/displayserver/linux/drm.c
index f76df154b..3710f1db2 100644
--- a/src/detection/displayserver/linux/drm.c
+++ b/src/detection/displayserver/linux/drm.c
@@ -36,31 +36,28 @@ static const char* drmParseSysfs(FFDisplayServerResult* result)
             continue;
         }
 
-        ffStrbufSubstrBefore(&drmDir, drmDirWithDnameLength);
-        ffStrbufAppendS(&drmDir, "/modes");
-
-        char modes[32];
-        if (ffReadFileData(drmDir.chars, sizeof(modes), modes) < 3)
-        {
-            ffStrbufSubstrBefore(&drmDir, drmDirLength);
-            continue;
-        }
-
         unsigned width = 0, height = 0;
+        double refreshRate = 0;
+        FF_STRBUF_AUTO_DESTROY name = ffStrbufCreate();
 
-        int scanned = sscanf(modes, "%ux%u", &width, &height);
-        if(scanned == 2 && width > 0 && height > 0)
+        ffStrbufSubstrBefore(&drmDir, drmDirWithDnameLength);
+        ffStrbufAppendS(&drmDir, "/edid");
+
+        uint8_t edidData[128];
+        if(ffReadFileData(drmDir.chars, sizeof(edidData), edidData) == sizeof(edidData))
         {
-            ffStrbufSubstrBefore(&drmDir, drmDirLength);
-            ffStrbufAppendS(&drmDir, entry->d_name);
-            ffStrbufAppendS(&drmDir, "/edid");
+            ffEdidGetName(edidData, &name);
+            ffEdidGetPreferredResolutionAndRefreshRate(edidData, &width, &height, &refreshRate);
+        }
+        else
+        {
+            ffStrbufSubstrBefore(&drmDir, drmDirWithDnameLength);
+            ffStrbufAppendS(&drmDir, "/modes");
 
-            FF_STRBUF_AUTO_DESTROY name = ffStrbufCreate();
-            uint8_t edidData[128];
-            if(ffReadFileData(drmDir.chars, sizeof(edidData), edidData) == sizeof(edidData))
-                ffEdidGetName(edidData, &name);
-            else
+            char modes[32];
+            if (ffReadFileData(drmDir.chars, sizeof(modes), modes) >= 3)
             {
+                sscanf(modes, "%ux%u", &width, &height);
                 const char* plainName = entry->d_name;
                 if (ffStrStartsWith(plainName, "card"))
                 {
@@ -69,20 +66,20 @@ static const char* drmParseSysfs(FFDisplayServerResult* result)
                 }
                 ffStrbufAppendS(&name, plainName);
             }
-
-            ffdsAppendDisplay(
-                result,
-                width, height,
-                0,
-                0, 0,
-                0,
-                &name,
-                FF_DISPLAY_TYPE_UNKNOWN,
-                false,
-                0
-            );
         }
 
+        ffdsAppendDisplay(
+            result,
+            width, height,
+            refreshRate,
+            0, 0,
+            0,
+            &name,
+            FF_DISPLAY_TYPE_UNKNOWN,
+            false,
+            0
+        );
+
         ffStrbufSubstrBefore(&drmDir, drmDirLength);
     }
 
diff --git a/src/util/edidHelper.c b/src/util/edidHelper.c
index 5fa2c662b..09931d22d 100644
--- a/src/util/edidHelper.c
+++ b/src/util/edidHelper.c
@@ -7,6 +7,25 @@ void ffEdidGetPhysicalResolution(const uint8_t edid[128], uint32_t* width, uint3
     *height = (((uint32_t) edid[dtd + 7] >> 4) << 8) | edid[dtd + 5];
 }
 
+void ffEdidGetPreferredResolutionAndRefreshRate(const uint8_t edid[128], uint32_t* width, uint32_t* height, double* refreshRate)
+{
+    for (uint32_t i = 0x36; i < 0x7E; i += 0x12)
+    { // read through descriptor blocks...
+        if (edid[i] != 0x00 && edid[i + 1] != 0x00)
+        { // a dtd
+            uint32_t hactive = edid[i+2] + ((edid[i + 4] & 0xf0) << 4);
+            uint32_t hblank = edid[i+3] + ((edid[i + 4] & 0x0f) << 8);
+            uint32_t vactive = edid[i+5] + ((edid[i + 7] & 0xf0) << 4);
+            uint32_t vblank = edid[i+6] + ((edid[i + 7] & 0x0f) << 8);
+            uint32_t pixclk = (edid[i+1] << 8) | (edid[i]);
+            *width = hactive;
+            *height = vactive;
+            *refreshRate = (double)pixclk * 10000 / (double)(hactive+hblank) / (double)(vactive+vblank);
+            return;
+        }
+    }
+}
+
 void ffEdidGetVendorAndModel(const uint8_t edid[128], FFstrbuf* result)
 {
     // https://github.com/jinksong/read_edid/blob/master/parse-edid/parse-edid.c
diff --git a/src/util/edidHelper.h b/src/util/edidHelper.h
index 6e768ddf9..cad9e6ce9 100644
--- a/src/util/edidHelper.h
+++ b/src/util/edidHelper.h
@@ -5,6 +5,7 @@
 
 void ffEdidGetVendorAndModel(const uint8_t edid[128], FFstrbuf* result);
 bool ffEdidGetName(const uint8_t edid[128], FFstrbuf* name);
+void ffEdidGetPreferredResolutionAndRefreshRate(const uint8_t edid[128], uint32_t* width, uint32_t* height, double* refreshRate);
 void ffEdidGetPhysicalResolution(const uint8_t edid[128], uint32_t* width, uint32_t* height);
 void ffEdidGetPhysicalSize(const uint8_t edid[128], uint32_t* width, uint32_t* height); // in mm
 void ffEdidGetSerialAndManufactureDate(const uint8_t edid[128], uint32_t* serial, uint16_t* year, uint16_t* week);