[Mesa-dev] [PATCH] wsi: allow to override the present mode with MESA_VK_WSI_PRESENT_MODE

[Samuel Pitoiset]

This is common to all Vulkan drivers and all WSI.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107391
Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---
 src/vulkan/wsi/wsi_common.c         | 19 +++++++++++++++++++
 src/vulkan/wsi/wsi_common_display.c |  2 ++
 src/vulkan/wsi/wsi_common_private.h |  2 ++
 src/vulkan/wsi/wsi_common_wayland.c |  2 ++
 src/vulkan/wsi/wsi_common_x11.c     |  2 ++
 5 files changed, 27 insertions(+)

diff --git a/src/vulkan/wsi/wsi_common.c b/src/vulkan/wsi/wsi_common.c
index 3cba0a4b06e..77f369f686d 100644
--- a/src/vulkan/wsi/wsi_common.c
+++ b/src/vulkan/wsi/wsi_common.c
@@ -29,6 +29,7 @@
 #include <time.h>
 #include <unistd.h>
 #include <xf86drm.h>
+#include <stdlib.h>
 
 VkResult
 wsi_device_init(struct wsi_device *wsi,
@@ -202,6 +203,24 @@ fail:
    return result;
 }
 
+void
+wsi_swapchain_override_present_mode(struct wsi_swapchain *swapchain)
+{
+   if (getenv("MESA_VK_WSI_PRESENT_MODE")) {
+      const char *mode = getenv("MESA_VK_WSI_PRESENT_MODE");
+
+      if (!strcmp(mode, "fifo")) {
+         swapchain->present_mode = VK_PRESENT_MODE_FIFO_KHR;
+      } else if (!strcmp(mode, "mailbox")) {
+         swapchain->present_mode = VK_PRESENT_MODE_MAILBOX_KHR;
+      } else if (!strcmp(mode, "immediate")) {
+         swapchain->present_mode = VK_PRESENT_MODE_IMMEDIATE_KHR;
+      } else {
+         unreachable("Invalid MESA_VK_WSI_PRESENT_MODE value");
+      }
+   }
+}
+
 void
 wsi_swapchain_finish(struct wsi_swapchain *chain)
 {
diff --git a/src/vulkan/wsi/wsi_common_display.c b/src/vulkan/wsi/wsi_common_display.c
index 09c18315623..36ddb07a5bf 100644
--- a/src/vulkan/wsi/wsi_common_display.c
+++ b/src/vulkan/wsi/wsi_common_display.c
@@ -1765,6 +1765,8 @@ wsi_display_surface_create_swapchain(
 
    chain->surface = (VkIcdSurfaceDisplay *) icd_surface;
 
+   wsi_swapchain_override_present_mode(&chain->base);
+
    for (uint32_t image = 0; image < chain->base.image_count; image++) {
       result = wsi_display_image_init(device, &chain->base,
                                       create_info, allocator,
diff --git a/src/vulkan/wsi/wsi_common_private.h b/src/vulkan/wsi/wsi_common_private.h
index a6f49fc3124..5ed4029ed70 100644
--- a/src/vulkan/wsi/wsi_common_private.h
+++ b/src/vulkan/wsi/wsi_common_private.h
@@ -78,6 +78,8 @@ wsi_swapchain_init(const struct wsi_device *wsi,
                    VkDevice device,
                    const VkSwapchainCreateInfoKHR *pCreateInfo,
                    const VkAllocationCallbacks *pAllocator);
+void
+wsi_swapchain_override_present_mode(struct wsi_swapchain *swapchain);
 
 void wsi_swapchain_finish(struct wsi_swapchain *chain);
 
diff --git a/src/vulkan/wsi/wsi_common_wayland.c b/src/vulkan/wsi/wsi_common_wayland.c
index 03a47028ef2..dcb2f8733f6 100644
--- a/src/vulkan/wsi/wsi_common_wayland.c
+++ b/src/vulkan/wsi/wsi_common_wayland.c
@@ -1015,6 +1015,8 @@ wsi_wl_surface_create_swapchain(VkIcdSurfaceBase *icd_surface,
    chain->vk_format = pCreateInfo->imageFormat;
    chain->drm_format = wl_drm_format_for_vk_format(chain->vk_format, alpha);
 
+   wsi_swapchain_override_present_mode(&chain->base);
+
    if (pCreateInfo->oldSwapchain) {
       /* If we have an oldSwapchain parameter, copy the display struct over
        * from the old one so we don't have to fully re-initialize it.
diff --git a/src/vulkan/wsi/wsi_common_x11.c b/src/vulkan/wsi/wsi_common_x11.c
index c87b9312636..f4dafb3b55e 100644
--- a/src/vulkan/wsi/wsi_common_x11.c
+++ b/src/vulkan/wsi/wsi_common_x11.c
@@ -1373,6 +1373,8 @@ x11_surface_create_swapchain(VkIcdSurfaceBase *icd_surface,
    chain->status = VK_SUCCESS;
    chain->has_dri3_modifiers = wsi_conn->has_dri3_modifiers;
 
+   wsi_swapchain_override_present_mode(&chain->base);
+
    /* If we are reallocating from an old swapchain, then we inherit its
     * last completion mode, to ensure we don't get into reallocation
     * cycles. If we are starting anew, we set 'COPY', as that is the only
-- 
2.21.0