Add begin/end_cpu_access

kms/framebuffer.py

@@ -8,6 +8,8 @@
 
 from typing import TYPE_CHECKING
 
+import pixutils.ioctl
+
 import kms
 import kms.uapi
 
@@ -51,6 +53,12 @@ def clear(self):
             ptr = ptrtype.from_buffer(self.map(idx))
             ctypes.memset(ptr, 0, self.size(idx))
 
+    def begin_cpu_access(self, access: str):
+        raise NotImplementedError()
+
+    def end_cpu_access(self):
+        raise NotImplementedError()
+
 
 class DumbFramebuffer(Framebuffer):
     def __init__(self, card: Card, width: int, height: int, format: kms.PixelFormat) -> None:
@@ -146,12 +154,33 @@ def fd(self, plane_idx):
 
         return p.prime_fd
 
+    def begin_cpu_access(self, access: str):
+        pass
+
+    def end_cpu_access(self):
+        pass
+
 
 class DmabufFramebuffer(Framebuffer):
+    class struct_dma_buf_sync(ctypes.Structure):
+        __slots__ = ['flags']
+        _fields_ = [('flags', ctypes.c_uint64)]
+
+    DMA_BUF_BASE = 'b'
+    DMA_BUF_IOCTL_SYNC = pixutils.ioctl.IOW(DMA_BUF_BASE, 0, struct_dma_buf_sync)
+
+    DMA_BUF_SYNC_READ = 1 << 0
+    DMA_BUF_SYNC_WRITE = 2 << 0
+    DMA_BUF_SYNC_RW = DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE
+    DMA_BUF_SYNC_START = 0 << 2
+    DMA_BUF_SYNC_END = 1 << 2
+
     def __init__(self, card: Card, width: int, height: int, format: kms.PixelFormat,
                  fds: list[int], pitches: list[int], offsets: list[int]) -> None:
         planes = []
 
+        self._sync_flags = 0
+
         for idx in range(len(format.planes)):
             args = kms.uapi.drm_prime_handle(fd=fds[idx])
             fcntl.ioctl(card.fd, kms.uapi.DRM_IOCTL_PRIME_FD_TO_HANDLE, args, True)
@@ -213,3 +242,36 @@ def fd(self, plane_idx):
         p = self.planes[plane_idx]
 
         return p.prime_fd
+
+    def begin_cpu_access(self, access: str):
+        if self._sync_flags != 0:
+            raise RuntimeError("begin_cpu sync already started")
+
+        if access == 'r':
+            self._sync_flags = DmabufFramebuffer.DMA_BUF_SYNC_READ
+        elif access == 'w':
+            self._sync_flags = DmabufFramebuffer.DMA_BUF_SYNC_WRITE
+        elif access == 'rw':
+            self._sync_flags = DmabufFramebuffer.DMA_BUF_SYNC_RW
+        else:
+            raise RuntimeError('Bad access type "{access}"')
+
+        dbs = DmabufFramebuffer.struct_dma_buf_sync()
+        # pylint: disable=attribute-defined-outside-init
+        dbs.flags = DmabufFramebuffer.DMA_BUF_SYNC_START | self._sync_flags
+
+        for p in self.planes:
+            fcntl.ioctl(p.prime_fd, DmabufFramebuffer.DMA_BUF_IOCTL_SYNC, dbs, False)
+
+    def end_cpu_access(self):
+        if self._sync_flags == 0:
+            raise RuntimeError("begin_cpu sync not started")
+
+        dbs = DmabufFramebuffer.struct_dma_buf_sync()
+        # pylint: disable=attribute-defined-outside-init
+        dbs.flags = DmabufFramebuffer.DMA_BUF_SYNC_END | self._sync_flags
+
+        for p in self.planes:
+            fcntl.ioctl(p.prime_fd, DmabufFramebuffer.DMA_BUF_IOCTL_SYNC, dbs, False)
+
+        self._sync_flags = 0

utils/kmstest.py

@@ -66,7 +66,9 @@ def main():
         fb = kms.DumbFramebuffer(card, width, height, fmt)
 
     ts1 = time.perf_counter()
+    fb.begin_cpu_access('w')
     draw_test_pattern(fb)
+    fb.end_cpu_access()
     ts2 = time.perf_counter()
     print(f'Drawing took {(ts2 - ts1) * 1000:.4f} ms')