ramips: fix mt7621 boot on v4.9

v4.9 CM code has a few bugs on this HW. Disable the GCR register access
during boot. This caused a cpu stall.

Signed-off-by: John Crispin <john@phrozen.org>

diff --git a/target/linux/ramips/patches-4.9/0098-disable_cm.patch b/target/linux/ramips/patches-4.9/0098-disable_cm.patch
new file mode 100644 (file)
index 0000000..6ea4909
--- /dev/null
+++ b/target/linux/ramips/patches-4.9/0098-disable_cm.patch
@@ -0,0 +1,21 @@
+Index: linux-4.9.14/arch/mips/kernel/mips-cm.c
+===================================================================
+--- linux-4.9.14.orig/arch/mips/kernel/mips-cm.c
++++ linux-4.9.14/arch/mips/kernel/mips-cm.c
+@@ -239,6 +239,7 @@ int mips_cm_probe(void)
+ 
+       /* disable CM regions */
+       write_gcr_reg0_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
++      /*
+       write_gcr_reg0_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
+       write_gcr_reg1_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
+       write_gcr_reg1_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
+@@ -246,7 +247,7 @@ int mips_cm_probe(void)
+       write_gcr_reg2_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
+       write_gcr_reg3_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
+       write_gcr_reg3_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
+-
++*/
+       /* probe for an L2-only sync region */
+       mips_cm_probe_l2sync();
+