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

[Eric Engestrom]

On Tuesday, 2019-04-09 09:08:36 +0200, 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.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");

const char *mode = getenv("MESA_VK_WSI_PRESENT_MODE");
if (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");

unreachable() means the compiler is allowed to do anything, including
considering the application as dead.

Not something we want user to be able to do with a simple
`MESA_VK_WSI_PRESENT_MODE=0` :)

With an assert() instead, this is:
Reviewed-by: Eric Engestrom <eric.engestrom at intel.com>

> +      }
> +   }
> +}
> +
>  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
> 
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