drm/amd/display: Fix null-deref on vega20 with xgmi [Linux 5.3]

This Linux kernel change "drm/amd/display: Fix null-deref on vega20 with xgmi" is included in the Linux 5.3 release. This change is authored by Roman Li <Roman.Li [at] amd.com> on Tue Jun 18 11:25:25 2019 -0400. The commit for this change in Linux stable tree is 496091f (patch).

drm/amd/display: Fix null-deref on vega20 with xgmi

[Why]
After clkmgr rework it gets initialized after resource pool.
The clkmgr is used in resource pool init for xgmi path.
That causes driver crash on Vega20 with xgmi due to NULL deref.

[How]
Move xgmi compensation code to dce121_clk_mgr_construct()
That also allows to make dce121_clock_patch_xgmi_ss_info()
internal static function.

Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

There are 26 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 .../gpu/drm/amd/display/dc/clk_mgr/dce120/dce120_clk_mgr.c | 14 +++++++++++---
 drivers/gpu/drm/amd/display/dc/dce120/dce120_resource.c    | 10 ----------
 drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr.h            |  2 --
 3 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dce120/dce120_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dce120/dce120_clk_mgr.c
index 08f2e25..906310c 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dce120/dce120_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dce120/dce120_clk_mgr.c
@@ -30,6 +30,7 @@
 #include "dce110/dce110_clk_mgr.h"
 #include "dce120_clk_mgr.h"
 #include "dce100/dce_clk_mgr.h"
+#include "dce120/dce120_hw_sequencer.h"

 static const struct state_dependent_clocks dce120_max_clks_by_state[] = {
 /*ClocksStateInvalid - should not be used*/
@@ -45,16 +46,15 @@

 /**
  * dce121_clock_patch_xgmi_ss_info() - Save XGMI spread spectrum info
- * @clk_mgr: clock manager base structure
+ * @clk_mgr_dce: clock manager internal structure
  *
  * Reads from VBIOS the XGMI spread spectrum info and saves it within
  * the dce clock manager. This operation will overwrite the existing dprefclk
  * SS values if the vBIOS query succeeds. Otherwise, it does nothing. It also
  * sets the ->xgmi_enabled flag.
  */
-void dce121_clock_patch_xgmi_ss_info(struct clk_mgr *clk_mgr_base)
+static void dce121_clock_patch_xgmi_ss_info(struct clk_mgr_internal *clk_mgr_dce)
 {
-   struct clk_mgr_internal *clk_mgr_dce = TO_CLK_MGR_INTERNAL(clk_mgr_base);
    enum bp_result result;
    struct spread_spectrum_info info = { { 0 } };
    struct dc_bios *bp = clk_mgr_dce->base.ctx->dc_bios;
@@ -141,5 +141,13 @@ void dce121_clk_mgr_construct(struct dc_context *ctx, struct clk_mgr_internal *c
 {
    dce120_clk_mgr_construct(ctx, clk_mgr);
    clk_mgr->base.dprefclk_khz = 625000;
+
+   /*
+    * The xGMI enabled info is used to determine if audio and display
+    * clocks need to be adjusted with the WAFL link's SS info.
+    */
+   if (dce121_xgmi_enabled(ctx->dc->hwseq))
+       dce121_clock_patch_xgmi_ss_info(clk_mgr);
+
 }

diff --git a/drivers/gpu/drm/amd/display/dc/dce120/dce120_resource.c b/drivers/gpu/drm/amd/display/dc/dce120/dce120_resource.c
index afa1c60..719c020 100644
--- a/drivers/gpu/drm/amd/display/dc/dce120/dce120_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dce120/dce120_resource.c
@@ -1163,16 +1163,6 @@ static bool construct(
    if (!resource_construct(num_virtual_links, dc, &pool->base, res_funcs))
        goto res_create_fail;

-   /*
-    * This is a bit of a hack. The xGMI enabled info is used to determine
-    * if audio and display clocks need to be adjusted with the WAFL link's
-    * SS info. This is a responsiblity of the clk_mgr. But since MMHUB is
-    * under hwseq, and the relevant register is in MMHUB, we have to do it
-    * here.
-    */
-   if (is_vg20 && dce121_xgmi_enabled(dc->hwseq))
-       dce121_clock_patch_xgmi_ss_info(dc->clk_mgr);
-
    /* Create hardware sequencer */
    if (!dce120_hw_sequencer_create(dc))
        goto controller_create_fail;
diff --git a/drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr.h b/drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr.h
index 721e131..36ebd5b 100644
--- a/drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr.h
@@ -53,8 +53,6 @@ struct clk_mgr_funcs {
    void (*enable_pme_wa) (struct clk_mgr *clk_mgr);
 };

-void dce121_clock_patch_xgmi_ss_info(struct clk_mgr *clk_mgr_base);
-
 struct clk_mgr {
    struct dc_context *ctx;
    struct clk_mgr_funcs *funcs;

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