intel: Add INTEL_DEBUG=nofc for disabling fast clears

Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>

docs/envvars.html

@@ -307,6 +307,8 @@ See the <a href="xlibdriver.html">Xlib software driver page</a> for details.
    <dd>disable instruction compaction</dd>
    <dt><code>nodualobj</code></dt>
    <dd>suppress generation of dual-object geometry shader code</dd>
+   <dt><code>nofc</code></dt>
+   <dd>disable fast clears</dd>
    <dt><code>norbc</code></dt>
    <dd>disable single sampled render buffer compression</dd>
    <dt><code>optimizer</code></dt>

src/intel/dev/gen_debug.c

@@ -89,6 +89,7 @@ static const struct debug_control debug_control[] = {
    { "tcs8",        DEBUG_TCS_EIGHT_PATCH },
    { "bt",          DEBUG_BT },
    { "pc",          DEBUG_PIPE_CONTROL },
+   { "nofc",        DEBUG_NO_FAST_CLEAR },
    { NULL,    0 }
 };
 

src/intel/dev/gen_debug.h

@@ -87,6 +87,7 @@ extern uint64_t INTEL_DEBUG;
 #define DEBUG_TCS_EIGHT_PATCH     (1ull << 43)
 #define DEBUG_BT                  (1ull << 44)
 #define DEBUG_PIPE_CONTROL        (1ull << 45)
+#define DEBUG_NO_FAST_CLEAR       (1ull << 46)
 
 /* These flags are not compatible with the disk shader cache */
 #define DEBUG_DISK_CACHE_DISABLE_MASK DEBUG_SHADER_TIME