drm/nouveau/kms/nv50-: Program notifier offset before requesting disp caps

Not entirely sure why this never came up when I originally tested this
(maybe some BIOSes already have this setup?) but the ->caps_init vfunc
appears to cause the display engine to throw an exception on driver
init, at least on my ThinkPad P72:

nouveau 0000:01:00.0: disp: chid 0 mthd 008c data 00000000 0000508c 0000102b

This is magic nvidia speak for "You need to have the DMA notifier offset
programmed before you can call NV507D_GET_CAPABILITIES." So, let's fix
this by doing that, and also perform an update afterwards to prevent
racing with the GPU when reading capabilities.

v2:
* Don't just program the DMA notifier offset, make sure to actually
  perform an update
v3:
* Don't call UPDATE()
* Actually read the correct notifier fields, as apparently the
  CAPABILITIES_DONE field lives in a different location than the main
  NV_DISP_CORE_NOTIFIER_1 field. As well, 907d+ use a different
  CAPABILITIES_DONE field then pre-907d cards.
v4:
* Don't forget to check the return value of core507d_read_caps()
v5:
* Get rid of NV50_DISP_CAPS_NTFY[14], use NV50_DISP_CORE_NTFY
* Disable notifier after calling GetCapabilities()

Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: 4a2cb4181b07 ("drm/nouveau/kms/nv50-: Probe SOR and PIOR caps for DP interlacing support")
Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 35 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/dispnv50/core907d.c b/drivers/gpu/drm/nouveau/dispnv50/core907d.c
index b17c03529c78..8564d4dffaff 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/core907d.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/core907d.c
@@ -22,11 +22,45 @@
 #include "core.h"
 #include "head.h"
 
+#include <nvif/push507c.h>
+#include <nvif/timer.h>
+
+#include <nvhw/class/cl907d.h>
+
+#include "nouveau_bo.h"
+
+int
+core907d_caps_init(struct nouveau_drm *drm, struct nv50_disp *disp)
+{
+	struct nv50_core *core = disp->core;
+	struct nouveau_bo *bo = disp->sync;
+	s64 time;
+	int ret;
+
+	NVBO_WR32(bo, NV50_DISP_CORE_NTFY, NV907D_CORE_NOTIFIER_3, CAPABILITIES_4,
+				     NVDEF(NV907D_CORE_NOTIFIER_3, CAPABILITIES_4, DONE, FALSE));
+
+	ret = core507d_read_caps(disp);
+	if (ret < 0)
+		return ret;
+
+	time = nvif_msec(core->chan.base.device, 2000ULL,
+			 if (NVBO_TD32(bo, NV50_DISP_CORE_NTFY,
+				       NV907D_CORE_NOTIFIER_3, CAPABILITIES_4, DONE, ==, TRUE))
+				 break;
+			 usleep_range(1, 2);
+			 );
+	if (time < 0)
+		NV_ERROR(drm, "core caps notifier timeout\n");
+
+	return 0;
+}
+
 static const struct nv50_core_func
 core907d = {
 	.init = core507d_init,
 	.ntfy_init = core507d_ntfy_init,
-	.caps_init = core507d_caps_init,
+	.caps_init = core907d_caps_init,
 	.ntfy_wait_done = core507d_ntfy_wait_done,
 	.update = core507d_update,
 	.head = &head907d,