From 8a6eea3132749f35860b2bc7c4434cde8955b3de Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Tue, 16 Aug 2022 07:06:05 +0300
Subject: [PATCH] queue family selection

---
 src/vk.c |   69 ++++++++++++++++++++++++++++++++++++++++++++++----------------
 src/vk.h |   11 ++++++++++
 2 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/src/vk.c b/src/vk.c
index ca03b35..82b1ccf 100644
--- a/src/vk.c
+++ b/src/vk.c
@@ -65,9 +65,9 @@ static int initflags;
 
 static VkInstance vk;
 static VkPhysicalDevice vkpdev;
-static int vkqfam_idx, vkqfam_maxq;
+static VkQueueFamilyProperties *qfam;
+static uint32_t num_qfam;
 static VkDevice vkdev;
-static VkQueue vkq;
 static VkSurfaceKHR vksurf;
 static VkSurfaceCapabilitiesKHR vksurf_caps;
 static int vksurf_numfmt, vksurf_selfmt;
@@ -176,6 +176,51 @@ int vk_reshape(int xsz, int ysz)
 	return 0;
 }
 
+int vk_find_qfamily(unsigned int flags)
+{
+	int i, famidx = -1;
+	VkBool32 can_pres;
+
+	if(!qfam) return -1;	/* not initialized I guess... */
+
+	for(i=0; i<num_qfam; i++) {
+		vkGetPhysicalDeviceSurfaceSupportKHR(vkpdev, i, vksurf, &can_pres);
+
+		if((flags & VKQ_PRESENT) && !can_pres) {
+			continue;
+		}
+		if((flags & VKQ_GFX) && !(qfam[i].queueFlags & VK_QUEUE_GRAPHICS_BIT)) {
+			continue;
+		}
+		if((flags & VKQ_COMPUTE) && !(qfam[i].queueFlags & VK_QUEUE_COMPUTE_BIT)) {
+			continue;
+		}
+
+		return i;	/* found a suitabe queue family */
+	}
+
+	return -1;
+}
+
+VkQueue vk_getq_fam(int fam, int n)
+{
+	VkQueue q;
+
+	if(fam < 0) return 0;
+	if(n < 0 || n >= qfam[fam].queueCount) {
+		fprintf(stderr, "vk_getq_fam: invalid index %d, family %d has %d queues\n",
+			   n, fam, qfam[fam].queueCount);
+		return 0;
+	}
+
+	vkGetDeviceQueue(vkdev, fam, n, &q);
+	return q;
+}
+
+VkQueue vk_getq(unsigned int flags)
+{
+	return vk_getq_fam(vk_find_qfamily(flags), 0);
+}
 
 int vk_create_rpass(void)
 {
@@ -557,10 +602,9 @@ static int create_surface(void)
 
 int choose_phys_dev(void)
 {
-	uint32_t i, num_pdev, num_qfam, score, best_score, best_dev;
+	uint32_t i, num_pdev, score, best_score, best_dev;
 	VkPhysicalDevice *pdev;
 	VkPhysicalDeviceProperties pdevprop;
-	VkQueueFamilyProperties *qfam;
 	VkBool32 can_pres;
 
 	vkEnumeratePhysicalDevices(vk, &num_pdev, 0);
@@ -591,21 +635,12 @@ int choose_phys_dev(void)
 	}
 	vkpdev = pdev[best_dev];
 
+	if(qfam) free(qfam);
+
 	vkGetPhysicalDeviceQueueFamilyProperties(vkpdev, &num_qfam, 0);
 	qfam = malloc_nf(num_qfam * sizeof *qfam);
 	vkGetPhysicalDeviceQueueFamilyProperties(vkpdev, &num_qfam, qfam);
 
-	vkqfam_idx = -1;
-	for(i=0; i<num_qfam; i++) {
-		vkGetPhysicalDeviceSurfaceSupportKHR(vkpdev, i, vksurf, &can_pres);
-		if(qfam[i].queueCount && (qfam[i].queueFlags & VK_QUEUE_GRAPHICS_BIT) && can_pres) {
-			vkqfam_maxq = qfam[i].queueCount;
-			vkqfam_idx = i;
-			break;
-		}
-	}
-
-	free(qfam);
 	free(pdev);
 	choose_pixfmt();
 	return 0;
@@ -646,7 +681,7 @@ static int create_device(void)
 	}
 
 	qinf.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
-	qinf.queueFamilyIndex = vkqfam_idx;
+	qinf.queueFamilyIndex = vk_find_qfamily(VKQ_GFX | VKQ_PRESENT);
 	qinf.queueCount = 1;
 	qinf.pQueuePriorities = &prio;
 
@@ -661,8 +696,6 @@ static int create_device(void)
 		fprintf(stderr, "failed to create vulkan device\n");
 		return -1;
 	}
-
-	vkGetDeviceQueue(vkdev, vkqfam_idx, 0, &vkq);
 	return 0;
 }
 
diff --git a/src/vk.h b/src/vk.h
index 470f757..319fa99 100644
--- a/src/vk.h
+++ b/src/vk.h
@@ -10,6 +10,13 @@ enum {
 	VKINIT_RAY		= 0x100
 };
 
+/* queue capability flags for vk_find_qfamily */
+enum {
+	VKQ_GFX			= 1,
+	VKQ_COMPUTE		= 2,
+	VKQ_PRESENT		= 4
+};
+
 void vk_init_xwin(Display *dpy, Window win);
 
 int vk_init(unsigned int flags, unsigned int *usedflags);
@@ -17,6 +24,10 @@ void vk_cleanup(void);
 
 int vk_reshape(int xsz, int ysz);
 
+int vk_find_qfamily(unsigned int flags);
+VkQueue vk_getq_fam(int fam, int n);
+VkQueue vk_getq(unsigned int flags);
+
 int vk_create_rpass(void);
 void vk_free_rpass(int rp);
 void vk_rpass_colorbuf(int rp, int fmt, int n);
-- 
1.7.10.4