nb/intel/sandybridge/raminit: add additional fallbacks

Add the following fallbacks:
* Try decreasing clock frequency.
   In case of DDR1600 the next possible value of DDR1333 is being used.
* Try decreasing clock frequency.
   In case of DDR1333 the next possible value of DDR1066 is being used.
* Disable failing channel.
   The system may be able to boot with a single channel enabled.

The fallbacks are untested.

Change-Id: I3be7034ad25312b3ebf47a54f335a3893f8d7cc1
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/14173
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/src/northbridge/intel/sandybridge/raminit.c b/src/northbridge/intel/sandybridge/raminit.c
index 3c606e17c2..0c191b2abd 100644
--- a/src/northbridge/intel/sandybridge/raminit.c
+++ b/src/northbridge/intel/sandybridge/raminit.c
@@ -201,6 +201,7 @@ typedef struct ramctr_timing_st {
 #define MAX_TIMA 127
 
 #define MAKE_ERR ((channel<<16)|(slotrank<<8)|1)
+#define GET_ERR_CHANNEL(x) (x>>16)
 
 static void program_timings(ramctr_timing * ctrl, int channel);
 
@@ -241,6 +242,18 @@ static void toggle_io_reset(void) {
 }
 
 /*
+ * Disable a channel in ramctr_timing.
+ */
+static void disable_channel(ramctr_timing *ctrl, int channel) {
+	ctrl->rankmap[channel] = 0;
+	memset(&ctrl->rank_mirror[channel][0], 0, sizeof(ctrl->rank_mirror[0]));
+	ctrl->channel_size_mb[channel] = 0;
+	ctrl->cmd_stretch[channel] = 0;
+	ctrl->mad_dimm[channel] = 0;
+	memset(&ctrl->timings[channel][0], 0, sizeof(ctrl->timings[0]));
+}
+
+/*
  * Fill cbmem with information for SMBIOS type 17.
  */
 static void fill_smbios17(ramctr_timing *ctrl)
@@ -4252,6 +4265,37 @@ void init_dram_ddr3(spd_raw_data *spds, int mobile, int min_tck,
 
 		err = try_init_dram_ddr3(&ctrl, fast_boot, s3resume, me_uma_size);
 	}
+
+	if (err && (ctrl.tCK < TCK_400MHZ)) {
+		/* fallback: lower clock frequency */
+		printk(BIOS_ERR, "RAM training failed, trying fallback.\n");
+		printram("Decreasing clock frequency.\n");
+		ctrl.tCK++;
+		err = try_init_dram_ddr3(&ctrl, fast_boot, s3resume, me_uma_size);
+	}
+
+	if (err && (ctrl.tCK < TCK_400MHZ)) {
+		/* fallback: lower clock frequency */
+		printk(BIOS_ERR, "RAM training failed, trying fallback.\n");
+		printram("Decreasing clock frequency.\n");
+		ctrl.tCK++;
+		err = try_init_dram_ddr3(&ctrl, fast_boot, s3resume, me_uma_size);
+	}
+
+	if (err) {
+		/* fallback: disable failing channel */
+		printk(BIOS_ERR, "RAM training failed, trying fallback.\n");
+		printram("Disable failing channel.\n");
+
+		/* Reset DDR3 frequency */
+		dram_find_spds_ddr3(spds, &ctrl);
+
+		/* disable failing channel */
+		disable_channel(&ctrl, GET_ERR_CHANNEL(err));
+
+		err = try_init_dram_ddr3(&ctrl, fast_boot, s3resume, me_uma_size);
+	}
+
 	if (err)
 		die("raminit failed");