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

[Samuel Pitoiset]

On 4/9/19 1:10 PM, Lionel Landwerlin wrote:
On 09/04/2019 08:08, Samuel Pitoiset wrote:
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.pitoi...@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");
+      }
+   }
+}
+


I would make this function a bit more robust.

Not all backends support all present modes.

Wayland only supports 2, while X11 supports 3.


There is some checking required to validate that we're not passing 
something invalid no?


I would also store the override in the wsi_device and only do the 
getenv() in wsi_device_init().

So it's only calling getenv once.


And then at swapchain creation do something like this maybe :


chain->base.present_mode =wsi_swapchain_get_present_mode(wsi_device, 
pCreateInfo->presentMode);
The whole approach looks better to me. Though, the only way to get the 
list of supported present modes is to call get_present_mode() but it 
requires a surface and we don't know the platform at device creation.


-Lionel


  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


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