st/nine: Make it optional to use a sw renderer

Until the problem described in
https://gitlab.freedesktop.org/mesa/mesa/-/issues/4489
is fixed, the advantages of using a sw renderer for the
sw rendering in nine are too small compared to the
disadvantages.

Add an option to control whether we use a sw renderer,
and make it so by default we don't.

Signed-off-by: Axel Davy <davyaxel0@gmail.com>
Acked-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10160>

2 files changed, 14 insertions, 7 deletions

diff --git a/src/gallium/targets/d3dadapter9/drm.c b/src/gallium/targets/d3dadapter9/drm.c
index cb05d5ca579..7a889a0d623 100644
--- a/src/gallium/targets/d3dadapter9/drm.c
+++ b/src/gallium/targets/d3dadapter9/drm.c
@@ -61,6 +61,7 @@ const driOptionDescription __driConfigOptionsNine[] = {
         DRI_CONF_NINE_DYNAMICTEXTUREWORKAROUND(true)
         DRI_CONF_NINE_SHADERINLINECONSTANTS(false)
         DRI_CONF_NINE_SHMEM_LIMIT()
+        DRI_CONF_NINE_FORCESWRENDERINGONCPU(false)
     DRI_CONF_SECTION_END
     DRI_CONF_SECTION_DEBUG
         DRI_CONF_OVERRIDE_VRAM_SIZE()
@@ -101,13 +102,13 @@ drm_destroy( struct d3dadapter9_context *ctx )
 {
     struct d3dadapter9drm_context *drm = (struct d3dadapter9drm_context *)ctx;
 
-    if (ctx->ref)
+    if (ctx->ref && ctx->hal != ctx->ref)
         ctx->ref->destroy(ctx->ref);
     /* because ref is a wrapper around hal, freeing ref frees hal too. */
     else if (ctx->hal)
         ctx->hal->destroy(ctx->hal);
 
-    if (drm->swdev)
+    if (drm->swdev && drm->swdev != drm->dev)
         pipe_loader_release(&drm->swdev, 1);
     if (drm->dev)
         pipe_loader_release(&drm->dev, 1);
@@ -214,6 +215,7 @@ drm_create_adapter( int fd,
     driOptionCache userInitOptions;
     int throttling_value_user = -2;
     int override_vendorid = -1;
+    bool sw_rendering;
 
     if (!ctx) { return E_OUTOFMEMORY; }
 
@@ -283,17 +285,18 @@ drm_create_adapter( int fd,
     ctx->base.shader_inline_constants = driQueryOptionb(&userInitOptions, "shader_inline_constants");
     ctx->base.memfd_virtualsizelimit = driQueryOptioni(&userInitOptions, "texture_memory_limit");
     ctx->base.override_vram_size = driQueryOptioni(&userInitOptions, "override_vram_size");
+    sw_rendering = driQueryOptionb(&userInitOptions, "force_sw_rendering_on_cpu");
 
     driDestroyOptionCache(&userInitOptions);
     driDestroyOptionInfo(&defaultInitOptions);
 
     /* wrap it to create a software screen that can share resources */
-    if (pipe_loader_sw_probe_wrapped(&ctx->swdev, ctx->base.hal))
+    if (sw_rendering && pipe_loader_sw_probe_wrapped(&ctx->swdev, ctx->base.hal))
         ctx->base.ref = pipe_loader_create_screen(ctx->swdev);
-
-    if (!ctx->base.ref) {
-        ERR("Couldn't wrap drm screen to swrast screen. Software devices "
-            "will be unavailable.\n");
+    else {
+        /* Use the hardware for sw rendering */
+        ctx->swdev = ctx->dev;
+        ctx->base.ref = ctx->base.hal;
     }
 
     /* read out PCI info */
diff --git a/src/util/driconf.h b/src/util/driconf.h
index 5467c150d31..dc31d5b0129 100644
--- a/src/util/driconf.h
+++ b/src/util/driconf.h
@@ -418,6 +418,10 @@
    DRI_CONF_OPT_I(texture_memory_limit, 512, 0, 0, \
                   "In MB the limit of virtual memory used for textures until shmem files are unmapped (default 512MB, 32bits only). If negative disables shmem. Set to a low amount to reduce virtual memory usage, but can inccur a small perf hit if too low.")
 
+#define DRI_CONF_NINE_FORCESWRENDERINGONCPU(def) \
+   DRI_CONF_OPT_B(force_sw_rendering_on_cpu, def, \
+                  "If set to false, emulates software rendering on the requested device, else uses a software renderer.")
+
 /**
  * \brief radeonsi specific configuration options
  */