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nb/intel/x4x: Work around a quirk

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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.

The workaround is to select stacked mode in this configuration.

Change-Id: I6f37ce15a4e98a4cdbd6d893f22846a65c8be021
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/26564
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
This commit is contained in:
Arthur Heymans
2018-05-26 15:05:09 +02:00
committed by Patrick Georgi
parent 0602ce67a6
commit 5a9dbde59c
1 changed files with 21 additions and 0 deletions
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21
src/northbridge/intel/x4x/raminit.c
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@@ -352,6 +352,26 @@ static void select_cas_dramfreq_ddr3(struct sysinfo *s,
}
}
/* With DDR3 and 533MHz mem clock and an enabled internal gfx device the display
is not usable in non stacked mode, so select stacked mode accordingly */
static void workaround_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_1066MHz)
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 @@ static void decode_spd_select_timings(struct sysinfo *s)
else
select_cas_dramfreq_ddr3(s, &saved_timings);
select_discrete_timings(s, &saved_timings);
workaround_stacked_mode(s);
}
static void find_dimm_config(struct sysinfo *s)