asahi: Add and support the no_fp16 driconf flag

This is the driconf equivalent of our debug no16 flag, which disables
fp16 support to work around apps using bad GLSL precision qualifiers.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25052>

src/gallium/drivers/asahi/agx_pipe.c

@@ -2150,6 +2150,10 @@ agx_screen_create(int fd, struct renderonly *ro,
    driParseConfigFiles(config->options, config->options_info, 0, "asahi", NULL,
                        NULL, NULL, 0, NULL, 0);
 
+   /* Forward no16 flag from driconf */
+   if (driQueryOptionb(config->options, "no_fp16"))
+      agx_screen->dev.debug |= AGX_DBG_NO16;
+
    agx_screen->dev.fd = fd;
    agx_screen->dev.ro = ro;
 

src/gallium/drivers/asahi/driinfo_asahi.h

@@ -2,4 +2,5 @@
 
 /* clang-format off */
 DRI_CONF_SECTION_MISCELLANEOUS
+   DRI_CONF_NO_FP16(false)
 DRI_CONF_SECTION_END

src/util/driconf.h

@@ -465,6 +465,10 @@
    DRI_CONF_OPT_B(allow_multisampled_copyteximage, def, \
                   "Allow CopyTexSubImage and other to copy sampled framebuffer")
 
+#define DRI_CONF_NO_FP16(def) \
+   DRI_CONF_OPT_B(no_fp16, def, \
+                  "Disable 16-bit float support")
+
 /**
  * \brief Initialization configuration options
  */