gralloc: Update freed buffermask at alloc

This fixes screen tearing because of the change of HIDL behavior.
The buffer is freed before the next allocation causing the
bufferslots always be unused at allocation. Only the first buffer
in the framebuffer /dev/graphics/fb0 was used.

Thanks to @Chronomonochrome for pointing out the issue in gralloc.

Change-Id: If1f6eb667506743cca828fbf87a45e7c2ee849a9

2 files changed, 12 insertions, 1 deletions

diff --git a/exynos4/hal/include/gralloc_priv.h b/exynos4/hal/include/gralloc_priv.h
index a230d03..98fdac0 100644
--- a/exynos4/hal/include/gralloc_priv.h
+++ b/exynos4/hal/include/gralloc_priv.h
@@ -61,6 +61,8 @@ struct private_module_t {
     uint32_t flags;
     uint32_t numBuffers;
     uint32_t bufferMask;
+    uint32_t bufferFreedMask;
+
     pthread_mutex_t lock;
     buffer_handle_t currentBuffer;
     int ion_client;
diff --git a/exynos4/hal/libgralloc_ump/alloc_device.cpp b/exynos4/hal/libgralloc_ump/alloc_device.cpp
index 1b64dfa..adbc527 100644
--- a/exynos4/hal/libgralloc_ump/alloc_device.cpp
+++ b/exynos4/hal/libgralloc_ump/alloc_device.cpp
@@ -460,14 +460,21 @@ static int gralloc_alloc_framebuffer_locked(alloc_device_t* dev, size_t size, in
     ALOGD_IF(debug_level > 0, "%s current=0x%x vaddr=0x%x l_paddr=0x%x before", __func__, current, vaddr, l_paddr);
 
     /* find a free slot */
+    uint32_t freeSlot = numBuffers -1;
     for (uint32_t i = 0; i < numBuffers; i++) {
         if ((bufferMask & (1LU<<i)) == 0) {
             m->bufferMask |= (1LU<<i);
+            freeSlot = i;
             break;
         }
         current += bufferSize;
         l_paddr = vaddr + current;
     }
+    ALOGE("%d: Using bufferslot:%d", __func__, freeSlot);
+
+    /* Update buffermask with freed slots */
+    m->bufferMask ^= m->bufferFreedMask;
+    m->bufferFreedMask &= m->bufferMask;
 
     ALOGD_IF(debug_level > 0, "%s current=0x%x vaddr=0x%x l_paddr=0x%x after", __func__, current, vaddr, l_paddr);
 
@@ -690,7 +697,9 @@ static int alloc_device_free(alloc_device_t* dev, buffer_handle_t handle)
         const size_t bufferSize = m->finfo.line_length * m->info.yres;
         int index = (hnd->base - m->framebuffer->base) / bufferSize;
 
-        m->bufferMask &= ~(1<<index);
+        /* Mark slot as freed */
+        m->bufferFreedMask |= (1LU<<index);
+
         close(hnd->fd);
 
     } else if (hnd->flags & private_handle_t::PRIV_FLAGS_USES_UMP) {