[Mesa-dev] [PATCH] intel: Fix initial MakeCurrent for drawables of multi screens

[Xiong Zhang]

This patch fix a regression caused by commit 11baad35.

Multi screens share one context. When the first screen call
intel_prepare_render(), it will set ctx->ViewportInitialized to
true, so the following screens don't have chance to call intel
_prepare_render().
If all screens run following gl command:
eglMakeCurrent()
glClearColor()
glClear()
eglSwapBuffers()
The first screen can run above command successfully. But the
following screen will occur segment fault error on eglSwapBuffers().
Because when following screens run:
eglMakeCurrent() won't call intel_prepare_render(); the width and
height of Draw buffer is zero, this causes glClear() return early
without calling Driver.Clear(); finaly Draw buffer doesn't have
bo, so eglSwapBuffers() occur segment fault error.

Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>
---
 src/mesa/drivers/dri/i965/brw_context.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index ef1ac45..3a935f9 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -917,6 +917,7 @@ intelMakeCurrent(__DRIcontext * driContextPriv,
    if (driContextPriv) {
       struct gl_context *ctx = &brw->ctx;
       struct gl_framebuffer *fb, *readFb;
+      struct intel_renderbuffer *rb = NULL;
 
       if (driDrawPriv == NULL && driReadPriv == NULL) {
          fb = _mesa_get_incomplete_framebuffer();
@@ -924,6 +925,7 @@ intelMakeCurrent(__DRIcontext * driContextPriv,
       } else {
          fb = driDrawPriv->driverPrivate;
          readFb = driReadPriv->driverPrivate;
+	 rb = intel_get_renderbuffer(fb, BUFFER_BACK_LEFT);
          driContextPriv->dri2.draw_stamp = driDrawPriv->dri2.stamp - 1;
          driContextPriv->dri2.read_stamp = driReadPriv->dri2.stamp - 1;
       }
@@ -935,10 +937,10 @@ intelMakeCurrent(__DRIcontext * driContextPriv,
       intel_gles3_srgb_workaround(brw, fb);
       intel_gles3_srgb_workaround(brw, readFb);
 
-      /* If the context viewport hasn't been initialized, force a call out to
-       * the loader to get buffers so we have a drawable size for the initial
-       * viewport. */
-      if (!brw->ctx.ViewportInitialized)
+      /* If the context viewport hasn't been initialized or buffers isn't 
+       * initialized, force a call out to the loader to get buffers so we 
+       * have a drawable size for the initial viewport. */
+      if (!brw->ctx.ViewportInitialized || (rb && !rb->mt))
          intel_prepare_render(brw);
 
       _mesa_make_current(ctx, fb, readFb);
-- 
1.8.3.2