[coreboot-gerrit] Change in coreboot[master]: nb/intel/x4x: Select stacked mode under some circumstances

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/26564


Change subject: nb/intel/x4x: Select stacked mode under some circumstances
......................................................................

nb/intel/x4x: Select stacked mode under some circumstances

It looks like this hardware has a bug where the display controller
does not work properly when dram is clocked 533MHz and the channels
are configured in non-stacked mode.

Change-Id: I6f37ce15a4e98a4cdbd6d893f22846a65c8be021
Signed-off-by: Arthur Heymans <arthur at aheymans.xyz>
---
M src/northbridge/intel/x4x/raminit.c
1 file changed, 21 insertions(+), 0 deletions(-)



  git pull ssh://review.coreboot.org:29418/coreboot refs/changes/64/26564/1

diff --git a/src/northbridge/intel/x4x/raminit.c b/src/northbridge/intel/x4x/raminit.c
index 9e649b0..016fbd9 100644
--- a/src/northbridge/intel/x4x/raminit.c
+++ b/src/northbridge/intel/x4x/raminit.c
@@ -352,6 +352,26 @@
 	}
 }
 
+/* With DDR3 and 533MHz mem clock and a gfx device enabled the display
+ * is not usable in stacked mode, so select stacked mode accordingly */
+static void select_stacked_mode(struct sysinfo *s)
+{
+	u32 deven;
+	/* Only a problem on DDR3 */
+	if (s->spd_type == DDR2)
+		return;
+	/* Does not matter if only one channel is populated */
+	if (!CHANNEL_IS_POPULATED(s->dimms, 0)
+			|| !CHANNEL_IS_POPULATED(s->dimms, 1))
+		return;
+	if (s->selected_timings.mem_clk != MEM_CLOCK_533MHz)
+		return;
+	/* IGD0EN gets disabled if not present  before this code runs */
+	deven = pci_read_config32(PCI_DEV(0, 0, 0), D0F0_DEVEN);
+	if (deven & IGD0EN)
+		s->stacked_mode = 1;
+}
+
 static int ddr3_save_dimminfo(u8 dimm_idx, u8 *raw_spd,
 		struct abs_timings *saved_timings, struct sysinfo *s)
 {
@@ -544,6 +564,7 @@
 	else
 		select_cas_dramfreq_ddr3(s, &saved_timings);
 	select_discrete_timings(s, &saved_timings);
+	select_stacked_mode(s);
 }
 
 static void find_dimm_config(struct sysinfo *s)

-- 
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Gerrit-Project: coreboot
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I6f37ce15a4e98a4cdbd6d893f22846a65c8be021
Gerrit-Change-Number: 26564
Gerrit-PatchSet: 1
Gerrit-Owner: Arthur Heymans <arthur at aheymans.xyz>
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