From a5ae9c4cc87509034be0e3eea0578ad83021739a Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Fri, 19 Aug 2022 11:43:39 +0300
Subject: [PATCH] mechanism to request queues before creating the device
 (vk_init_queue)

---
 src/vk.c |   59 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
 src/vk.h |    6 ++++--
 2 files changed, 54 insertions(+), 11 deletions(-)

diff --git a/src/vk.c b/src/vk.c
index 82b1ccf..6887460 100644
--- a/src/vk.c
+++ b/src/vk.c
@@ -62,6 +62,12 @@ static int have_ext(VkExtensionProperties *ext, int next, const char *name);
 static Display *dpy;
 static Window win;
 static int initflags;
+#define MAX_INIT_QUEUE	32
+static struct {
+	unsigned int flags;
+	int count;
+} initq[MAX_INIT_QUEUE];
+static int num_initq;
 
 static VkInstance vk;
 static VkPhysicalDevice vkpdev;
@@ -93,8 +99,23 @@ void vk_init_xwin(Display *d, Window w)
 	win = w;
 }
 
+void vk_init_queue(unsigned int qflags, int count)
+{
+	if(num_initq >= MAX_INIT_QUEUE) {
+		fprintf(stderr, "vk_init_queue: too many queues\n");
+		return;
+	}
+	initq[num_initq].flags = qflags;
+	initq[num_initq].count = count;
+	num_initq++;
+}
+
 int vk_init(unsigned int flags, unsigned int *usedflags)
 {
+	if(!num_initq) {
+		vk_init_queue(VKQ_GFX | VKQ_PRESENT, 1);
+	}
+
 	initflags = flags;
 	if(create_instance() == -1)	return -1;
 	if(create_surface() == -1) return -1;
@@ -648,12 +669,12 @@ int choose_phys_dev(void)
 
 static int create_device(void)
 {
-	float prio = 1.0f;
-	VkDeviceQueueCreateInfo qinf = {0};
+	float *prio;
+	VkDeviceQueueCreateInfo qinf[MAX_INIT_QUEUE] = {0};
 	VkPhysicalDeviceFeatures feat = {0};
 	VkDeviceCreateInfo devinf = {0};
 	const char *ext[ARRSZ(known_devext_list) + 16];
-	int i, num_ext;
+	int i, j, num_ext, qfam, totalq;
 
 	vkEnumerateDeviceExtensionProperties(vkpdev, 0, &dev_ext_count, 0);
 	dev_ext = malloc_nf(dev_ext_count * sizeof *dev_ext);
@@ -680,14 +701,34 @@ static int create_device(void)
 		}
 	}
 
-	qinf.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
-	qinf.queueFamilyIndex = vk_find_qfamily(VKQ_GFX | VKQ_PRESENT);
-	qinf.queueCount = 1;
-	qinf.pQueuePriorities = &prio;
+	totalq = 0;
+	for(i=0; i<num_initq; i++) {
+		totalq += initq[i].count;
+	}
+	if(totalq > 1024) {
+		fprintf(stderr, "create_device: arbitrary limit of total queues exceeded (%d)\n", totalq);
+		return -1;
+	}
+	prio = alloca(totalq * sizeof *prio);
+
+	for(i=0; i<num_initq; i++) {
+		if((qfam = vk_find_qfamily(initq[i].flags)) == -1) {
+			fprintf(stderr, "create_device: failed to find queue family (flags: 0x%2x)\n",
+					initq[i].flags);
+			return -1;
+		}
+		qinf[i].sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
+		qinf[i].queueFamilyIndex = qfam;
+		qinf[i].queueCount = initq[i].count;
+		qinf[i].pQueuePriorities = prio;
+		for(j=0; j<initq[i].count; i++) {
+			*prio++ = 1.0f;	/* all queue priorities 1 */
+		}
+	}
 
 	devinf.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
-	devinf.pQueueCreateInfos = &qinf;
-	devinf.queueCreateInfoCount = 1;
+	devinf.pQueueCreateInfos = qinf;
+	devinf.queueCreateInfoCount = num_initq;
 	devinf.pEnabledFeatures = &feat;
 	devinf.enabledExtensionCount = num_ext;
 	devinf.ppEnabledExtensionNames = ext;
diff --git a/src/vk.h b/src/vk.h
index 319fa99..3f765ac 100644
--- a/src/vk.h
+++ b/src/vk.h
@@ -10,14 +10,16 @@ enum {
 	VKINIT_RAY		= 0x100
 };
 
-/* queue capability flags for vk_find_qfamily */
+/* queue capability flags for vk_find_qfamily and vk_init_queue */
 enum {
 	VKQ_GFX			= 1,
 	VKQ_COMPUTE		= 2,
-	VKQ_PRESENT		= 4
+	VKQ_PRESENT		= 4,
+	VKQ_XFER		= 8
 };
 
 void vk_init_xwin(Display *dpy, Window win);
+void vk_init_queue(unsigned int qflags, int count);
 
 int vk_init(unsigned int flags, unsigned int *usedflags);
 void vk_cleanup(void);
-- 
1.7.10.4