Enable vsync on multiple pipes on top of v1.0.0

Signed-off-by: Eshe N Pickett <[email protected]>

.gitignore

@@ -0,0 +1,8 @@
+*.swp
+*.so
+*.o
+*.exe
+*.lib
+*.dll
+*~
+release/

README.md

@@ -4,16 +4,34 @@
 This program allows a system to alter their vertical sync firing times.
 This is sample code only and is only supported on 11th Gen Core. 
 
-Building steps:
-1) sudo apt install libdrm-dev libpciaccess-dev
-1) Type 'make release' from the main directory. It compiles everything and creates a 
+# Prerequisites
+The build system assumes the following, prior to executing the build steps:
+1) The system has an [Ubuntu OS](https://ubuntu.com/tutorials/install-ubuntu-desktop#1-overview)
+1) Libraries installed: `sudo apt install -y git build-essential make`
+
+# Building steps:
+1) Git clone this repository 
+1) `sudo apt install libdrm-dev libpciaccess-dev`
+    1) If the directory /usr/include/drm does not exist, you may need to also add `sudo apt install -y linux-libc-dev`
+1) Type `make release` from the main directory. It compiles everything and creates a 
    release folder which can then be copied to the target systems.
 
 Building of this program has been succesfully tested on both Ubuntu 20 and Fedora 30.
 
-Installing and running the programs:
+# Installing and running the programs:
 1) On the system, go to the directory where these files exist and set environment variable:
-export LD_LIBRARY_PATH=.
+```console
+export LD_LIBRARY_PATH=`pwd`
+``````
 2) On the primary system, run it as follows:
-	./synctest 
+	```console
+   ./synctest 
+   ```
+
 (Note by default this is set to move vsync by 1.0 ms.)
+
+# Helpful libraries to have installed
+If you are doing debug, it helps to have the following libraries installed:
+```
+apt install -y intel-gpu-tools edid-decode
+```

cmn/vsyncalter.h

@@ -10,7 +10,7 @@
 int vsync_lib_init();
 void vsync_lib_uninit();
 void synchronize_vsync(double time_diff);
-int get_vsync(long *vsync_array, int size);
+int get_vsync(long *vsync_array, int size, int pipe = 0);
 int find_enabled_combo_phys();
 
 #endif

lib/vsyncalter.cpp

@@ -121,6 +121,7 @@ typedef struct _vbl_info {
 	long *vsync_array;
 	int size;
 	int counter;
+	int pipe;
 } vbl_info;
 
 
@@ -354,6 +355,9 @@ static int make_timer(long expire_ms, void *user_ptr, timer_t *t)
 		return -1;
 	}
 
+	/* Ensure that alarm struct is zeroed out prior to use */
+	memset(&te, 0, sizeof te);
+
 	/* Set and enable alarm */
 	te.sigev_notify = SIGEV_SIGNAL;
 	te.sigev_signo = sig_no;
@@ -768,6 +772,33 @@ static void vblank_handler(int fd, unsigned int frame, unsigned int sec,
 	drmWaitVBlank(g_dev_fd, &vbl);
 }
 
+/*******************************************************************************
+ * Description
+ *  pipe_to_wait_for - This function determines the type of vblank synchronization to
+ *	use for the output.
+ *Parameters
+ * int pipe - Indicates which CRTC to get vblank for.  Knowing this, we
+ *	can determine which vblank sequence type to use for it.  Traditional
+ *	cards had only two CRTCs, with CRTC 0 using no special flags, and
+ *	CRTC 1 using DRM_VBLANK_SECONDARY.  The first bit of the pipe
+ *	Bits 1-5 of the pipe parameter are 5 bit wide pipe number between
+ *	0-31.  If this is non-zero it indicates we're dealing with a
+ *	multi-gpu situation and we need to calculate the vblank sync
+ *	using DRM_BLANK_HIGH_CRTC_MASK.
+ * Return val
+ *  int - The flag to OR in for drmWaitVBlank API
+ ******************************************************************************/
+unsigned int pipe_to_wait_for(int pipe)
+{
+	int ret = 0;
+	if (pipe > 1) {
+		ret = (pipe << DRM_VBLANK_HIGH_CRTC_SHIFT) & DRM_VBLANK_HIGH_CRTC_MASK;
+	} else if (pipe > 0) {
+		ret = DRM_VBLANK_SECONDARY;
+	}
+	return ret;
+}
+
 /*******************************************************************************
  * Description
  *  get_vsync - This function gets a list of vsyncs for the number of times
@@ -776,10 +807,12 @@ static void vblank_handler(int fd, unsigned int frame, unsigned int sec,
  *	long *vsync_array - The array in which vsync timestamps need to be given
  *	int size - The size of this array. This is also the number of times that we
  *	need to get the next few vsync timestamps.
+ *	int pipe - This is the pipe whose vblank is needed. Defaults to 0 if not
+ *	provided.
  * Return val
  *  int - 0 == SUCCESS, -1 = ERROR
  ******************************************************************************/
-int get_vsync(long *vsync_array, int size)
+int get_vsync(long *vsync_array, int size, int pipe)
 {
 	drmVBlank vbl;
 	int ret;
@@ -797,9 +830,12 @@ int get_vsync(long *vsync_array, int size)
 	handler_info.vsync_array = vsync_array;
 	handler_info.size = size;
 	handler_info.counter = 0;
+	handler_info.pipe = pipe;
 
 	/* Queue an event for frame + 1 */
-	vbl.request.type = (drmVBlankSeqType) (DRM_VBLANK_RELATIVE | DRM_VBLANK_EVENT);
+	vbl.request.type = (drmVBlankSeqType)
+		(DRM_VBLANK_RELATIVE | DRM_VBLANK_EVENT | pipe_to_wait_for(pipe));
+	DBG("vbl.request.type = 0x%X\n", vbl.request.type);
 	vbl.request.sequence = 1;
 	vbl.request.signal = (unsigned long)&handler_info;
 	ret = drmWaitVBlank(g_dev_fd, &vbl);
@@ -840,4 +876,4 @@ int get_vsync(long *vsync_array, int size)
 
 	close_device();
 	return 0;
-}
+}

synctest/Makefile

@@ -6,7 +6,7 @@ BINNAME=$(notdir $(PWD))
 MAKE += --no-print-directory
 export CC=g++
 export DBG_FLAGS?=-Ofast
-export LIBS=-L. -L../lib  -L/home/ssingh/workspace/tools/vsync/lib -lvsyncalter
+export LIBS=-L. -L../lib -lvsyncalter
 export INCLUDES=-I. -I../cmn
 export CFLAGS=-c -Wall
 export HEADERS=$(wildcard *.h)