commit 67b2c3161baa125ef239fabb49011f5218989aca
author Greg Hackmann <ghackmann@google.com> Mon Oct 01 13:31:26 2012 -0700
committer Greg Hackmann <ghackmann@google.com> Mon Oct 01 13:36:18 2012 -0700
tree 5ff91d19568ac44fc67cfde987e8568e2452a9a2
parent a46f3ffc8589d99c6273ada37c90d6fcf68be70b

hwc: enforce minimum window width

Windows narrower than the FIMD's DMA burst length (128 bytes) are
rejected by the kernel because they may wedge the FIMD.

Bug: 7257993
Change-Id: I145db16940bd972e4197a0851bfc992ad4ecdf45
Signed-off-by: Greg Hackmann <ghackmann@google.com>

libhwc/hwc.cpp

diff --git a/libhwc/hwc.cpp b/libhwc/hwc.cpp
index da72b0d..588b4df 100644
--- a/libhwc/hwc.cpp
+++ b/libhwc/hwc.cpp
@@ -58,6 +58,7 @@
 const int AVAILABLE_GSC_UNITS[] = { 0, 3 };
 const size_t NUM_GSC_UNITS = sizeof(AVAILABLE_GSC_UNITS) /
         sizeof(AVAILABLE_GSC_UNITS[0]);
+const size_t BURSTLEN_BYTES = 16 * 8;
 
 struct exynos5_hwc_composer_device_1_t;
 
@@ -661,6 +662,20 @@
             layer.sourceCrop.bottom < 0;
 }
 
+size_t exynos5_visible_width(hwc_layer_1_t &layer, int format,
+        struct exynos5_hwc_composer_device_1_t *pdev)
+{
+    int bpp;
+    if (exynos5_requires_gscaler(layer, format))
+        bpp = 32;
+    else
+        bpp = exynos5_format_to_bpp(format);
+    int left = max(layer.displayFrame.left, 0);
+    int right = min(layer.displayFrame.right, pdev->xres);
+
+    return (right - left) * bpp / 8;
+}
+
 bool exynos5_supports_overlay(hwc_layer_1_t &layer, size_t i,
         struct exynos5_hwc_composer_device_1_t *pdev)
 {
@@ -700,6 +715,10 @@
         ALOGW("\tlayer %u: off-screen", i);
         return false;
     }
+    if (exynos5_visible_width(layer, handle->format, pdev) < BURSTLEN_BYTES) {
+        ALOGV("\tlayer %u: visible area is too narrow", i);
+        return false;
+    }
 
     return true;
 }