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Commit 148bad07 authored by Ady Abraham's avatar Ady Abraham
Browse files

swapchain: increase the minimal buffer count to 3 

On Android, the compositor will latch buffers only if they are completed
(i.e. the gpu fence is signaled), which means 2 buffers would
be acquired from the buffer queue. If the client wants mailbox or
swap_interval=0 behavior, an additional buffer is needed for the app
to never block on dequeueBuffer.

Test: run Vk cube and observe buffer count
Test: CtsDeqpTestCases: dEQP-VK.wsi.*
Bug: 182887411
Change-Id: I4c6bcb85200c6646dd8c504b2d40471c7d6eeed6
parent a785b9a9

vulkan/libvulkan/swapchain.cpp

+33 −16
Original line number Diff line number Diff line
@@ -537,6 +537,30 @@ android_dataspace GetNativeDataspace(VkColorSpaceKHR colorspace) { 
    }

}



int get_min_buffer_count(ANativeWindow* window,

                         uint32_t* out_min_buffer_count) {

    constexpr int kExtraBuffers = 2;



    int err;

    int min_undequeued_buffers;

    err = window->query(window, NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS,

                        &min_undequeued_buffers);

    if (err != android::OK || min_undequeued_buffers < 0) {

        ALOGE(

            "NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS query failed: %s (%d) "

            "value=%d",

            strerror(-err), err, min_undequeued_buffers);

        if (err == android::OK) {

            err = android::UNKNOWN_ERROR;

        }

        return err;

    }



    *out_min_buffer_count =

        static_cast<uint32_t>(min_undequeued_buffers + kExtraBuffers);

    return android::OK;

}



}  // anonymous namespace



VKAPI_ATTR
@@ -848,15 +872,13 @@ VkResult GetPhysicalDeviceSurfacePresentModesKHR(VkPhysicalDevice pdev, 


    int err;

    int query_value;

    uint32_t min_buffer_count;

    ANativeWindow* window = SurfaceFromHandle(surface)->window.get();



    err = window->query(window, NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS, &query_value);

    if (err != android::OK || query_value < 0) {

        ALOGE("NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS query failed: %s (%d) value=%d",

              strerror(-err), err, query_value);

    err = get_min_buffer_count(window, &min_buffer_count);

    if (err != android::OK) {

        return VK_ERROR_SURFACE_LOST_KHR;

    }

    uint32_t min_undequeued_buffers = static_cast<uint32_t>(query_value);



    err = window->query(window, NATIVE_WINDOW_MAX_BUFFER_COUNT, &query_value);

    if (err != android::OK || query_value < 0) {
@@ -867,7 +889,7 @@ VkResult GetPhysicalDeviceSurfacePresentModesKHR(VkPhysicalDevice pdev, 
    uint32_t max_buffer_count = static_cast<uint32_t>(query_value);



    std::vector<VkPresentModeKHR> present_modes;

    if (min_undequeued_buffers + 1 < max_buffer_count)

    if (min_buffer_count < max_buffer_count)

        present_modes.push_back(VK_PRESENT_MODE_MAILBOX_KHR);

    present_modes.push_back(VK_PRESENT_MODE_FIFO_KHR);
@@ -1188,19 +1210,14 @@ VkResult CreateSwapchainKHR(VkDevice device, 
        }

    }



    int query_value;

    err = window->query(window, NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS,

                        &query_value);

    if (err != android::OK || query_value < 0) {

        ALOGE("window->query failed: %s (%d) value=%d", strerror(-err), err,

              query_value);

    uint32_t min_buffer_count;

    err = get_min_buffer_count(window, &min_buffer_count);

    if (err != android::OK) {

        return VK_ERROR_SURFACE_LOST_KHR;

    }

    uint32_t min_undequeued_buffers = static_cast<uint32_t>(query_value);



    uint32_t num_images =

        (swap_interval ? create_info->minImageCount

                       : std::max(3u, create_info->minImageCount)) -

        1 + min_undequeued_buffers;

        std::max(min_buffer_count, create_info->minImageCount);



    // Lower layer insists that we have at least two buffers. This is wasteful

    // and we'd like to relax it in the shared case, but not all the pieces are