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Optimize shadow buffer blit #127

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Optimize shadow buffer blit #127

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803fa7f
Introduce helper to detect buffer placement via usage
phreer Jun 24, 2025
c5a0236
Use client composition for dGPU local memory layers
phreer Jun 24, 2025
5604cca
Don't use shadow buffer for system memory layers
phreer Jun 24, 2025
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5 changes: 3 additions & 2 deletions backend/Backend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -123,8 +123,9 @@ bool Backend::IsClientLayer(HwcDisplay *display, HwcLayer *layer) {
!layer->IsLayerUsableAsDevice() ||
display->color_transform_hint() != HAL_COLOR_TRANSFORM_IDENTITY ||
(layer->GetLayerData().pi.RequireScalingOrPhasing() &&
display->GetHwc2()->GetResMan().ForcedScalingWithGpu()) ||
(!IsVideoLayer(layer) && IsDownScaling(layer)) ||
display->GetHwc2()->GetResMan().ForcedScalingWithGpu()) ||
(!IsVideoLayer(layer) && IsDownScaling(layer)) ||
(has_local_memory_flag(layer->GetLayerData().bi->usage) && !layer->GetAllowP2P()) ||
(!display->IsInHeadlessMode() && display->GetPipe().device->IsIvshmDev());
}

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3 changes: 2 additions & 1 deletion hwc2_device/HwcLayer.cpp
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Expand Up @@ -301,7 +301,8 @@ void HwcLayer::ImportFb() {
is_pixel_blend_mode_supported = false;

int kms_fd = parent_->GetPipe().device->GetFd();
bool use_shadow_fds = parent_->GetPipe().device->GetName() == "virtio_gpu" &&
bool use_shadow_fds = has_local_memory_flag(layer_data_.bi->usage) &&
parent_->GetPipe().device->GetName() == "virtio_gpu" &&
!allow_p2p_ && (intel_dgpu_fd() >= 0) &&
!virtio_gpu_allow_p2p(kms_fd) && InitializeBlitter(layer_data_.bi.value());
layer_data_.bi->use_shadow_fds = use_shadow_fds;
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3 changes: 3 additions & 0 deletions hwc2_device/HwcLayer.h
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Expand Up @@ -67,6 +67,9 @@ class HwcLayer {
return layer_data_;
}

bool GetAllowP2P() const {
return allow_p2p_;
}
// Layer hooks
HWC2::Error SetCursorPosition(int32_t /*x*/, int32_t /*y*/);
HWC2::Error SetLayerBlendMode(int32_t mode);
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6 changes: 6 additions & 0 deletions utils/intel_blit.h
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Expand Up @@ -22,6 +22,9 @@

#include "UniqueFd.h"

/* Buffer is allocated on dGPU local memory if this flag is set */
#define GRALLOC_USAGE_PRIVATE_2 (1ull << 30)

#define I915_TILING_4 9

struct intel_info {
Expand Down Expand Up @@ -49,6 +52,9 @@ int intel_create_buffer(struct intel_info *info,
uint64_t modifier, uint32_t *out_handle);
int intel_dgpu_fd();
bool virtio_gpu_allow_p2p(int virtgpu_fd);
inline bool has_local_memory_flag(uint64_t usage) {
return (usage & GRALLOC_USAGE_PRIVATE_2) != 0;
}

class IntelBlitter {
public:
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