From: José Fonseca <jfonseca@vmware.com>
Date: Fri, 14 Aug 2009 19:05:33 +0000 (+0100)
Subject: gallium: Always map for READ flag when DISCARD is not set.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=e3bc1fb6bcd3141df8ab9123c4f6c276f30f6649;p=mesa.git

gallium: Always map for READ flag when DISCARD is not set.

This prevents the driver from discarding a buffer when the whole buffer
is mapped for writing, but only a portion is effectively written.

This is a temporary fix, because WRITE shouldn't imply DISCARD.

The full fix implies using PIPE_BUFFER_USAGE_DISCARD, throughout
the code, and will go only into master.
---

diff --git a/src/gallium/include/pipe/p_inlines.h b/src/gallium/include/pipe/p_inlines.h
index cf176c92099..a5c1e8270a3 100644
--- a/src/gallium/include/pipe/p_inlines.h
+++ b/src/gallium/include/pipe/p_inlines.h
@@ -63,6 +63,13 @@ pipe_buffer_map(struct pipe_screen *screen,
    if(screen->buffer_map_range) {
       unsigned offset = 0;
       unsigned length = buf->size;
+
+      /* XXX: Actually we should be using/detecting DISCARD
+       * instead of assuming that WRITE implies discard */
+      if((usage & PIPE_BUFFER_USAGE_CPU_WRITE) &&
+         !(usage & PIPE_BUFFER_USAGE_DISCARD))
+         usage |= PIPE_BUFFER_USAGE_CPU_READ;
+
       return screen->buffer_map_range(screen, buf, offset, length, usage);
    }
    else