[PATCH 01/13] drm/i915/dram: Also apply the 16Gb DIMM w/a for larger DRAM chips

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

While the spec only asks us to do the WM0 latency bump for 16Gb
DRAM devices I believe we should apply it for larger DRAM chips.
At the time the w/a was added there were no larger chips on
the market, but I think I've seen at least 32Gb DDR4 chips
being available these days.

Whether it's possible to actually find suitable DIMMs for the
affected systems with largers chips I don't know. Also it's
not known whether the 1 usec latency bump would be sufficient
for larger chips. Someone would need to find such DIMMs and
test this. Fortunately we do have a bit of extra latency already
with the 1 usec bump, as the actual requirement was .4 usec for
for 16Gb chips.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/skl_watermark.c |  4 ++--
 drivers/gpu/drm/i915/soc/intel_dram.c        | 10 +++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 0b9c86042e78..b7482d428868 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -3209,9 +3209,9 @@ adjust_wm_latency(struct intel_display *display,
 	}
 
 	/*
-	 * WA Level-0 adjustment for 16Gb DIMMs: SKL+
+	 * WA Level-0 adjustment for 16Gb+ DIMMs: SKL+
 	 * If we could not get dimm info enable this WA to prevent from
-	 * any underrun. If not able to get DIMM info assume 16Gb DIMM
+	 * any underrun. If not able to get DIMM info assume 16Gb+ DIMM
 	 * to avoid any underrun.
 	 */
 	if (!display->platform.dg2 && dram_info->has_16gb_dimms)
diff --git a/drivers/gpu/drm/i915/soc/intel_dram.c b/drivers/gpu/drm/i915/soc/intel_dram.c
index 149527827624..8e81573022ff 100644
--- a/drivers/gpu/drm/i915/soc/intel_dram.c
+++ b/drivers/gpu/drm/i915/soc/intel_dram.c
@@ -335,7 +335,7 @@ static bool
 skl_is_16gb_dimm(const struct dram_dimm_info *dimm)
 {
 	/* Convert total Gb to Gb per DRAM device */
-	return dimm->size / (intel_dimm_num_devices(dimm) ?: 1) == 16;
+	return dimm->size / (intel_dimm_num_devices(dimm) ?: 1) >= 16;
 }
 
 static void
@@ -354,7 +354,7 @@ skl_dram_get_dimm_info(struct drm_i915_private *i915,
 	}
 
 	drm_dbg_kms(&i915->drm,
-		    "CH%u DIMM %c size: %u Gb, width: X%u, ranks: %u, 16Gb DIMMs: %s\n",
+		    "CH%u DIMM %c size: %u Gb, width: X%u, ranks: %u, 16Gb+ DIMMs: %s\n",
 		    channel, dimm_name, dimm->size, dimm->width, dimm->ranks,
 		    str_yes_no(skl_is_16gb_dimm(dimm)));
 }
@@ -384,7 +384,7 @@ skl_dram_get_channel_info(struct drm_i915_private *i915,
 	ch->is_16gb_dimm = skl_is_16gb_dimm(&ch->dimm_l) ||
 		skl_is_16gb_dimm(&ch->dimm_s);
 
-	drm_dbg_kms(&i915->drm, "CH%u ranks: %u, 16Gb DIMMs: %s\n",
+	drm_dbg_kms(&i915->drm, "CH%u ranks: %u, 16Gb+ DIMMs: %s\n",
 		    channel, ch->ranks, str_yes_no(ch->is_16gb_dimm));
 
 	return 0;
@@ -406,7 +406,7 @@ skl_dram_get_channels_info(struct drm_i915_private *i915, struct dram_info *dram
 	u32 val;
 	int ret;
 
-	/* Assume 16Gb DIMMs are present until proven otherwise */
+	/* Assume 16Gb+ DIMMs are present until proven otherwise */
 	dram_info->has_16gb_dimms = true;
 
 	val = intel_uncore_read(&i915->uncore,
@@ -438,7 +438,7 @@ skl_dram_get_channels_info(struct drm_i915_private *i915, struct dram_info *dram
 	drm_dbg_kms(&i915->drm, "Memory configuration is symmetric? %s\n",
 		    str_yes_no(dram_info->symmetric_memory));
 
-	drm_dbg_kms(&i915->drm, "16Gb DIMMs: %s\n",
+	drm_dbg_kms(&i915->drm, "16Gb+ DIMMs: %s\n",
 		    str_yes_no(dram_info->has_16gb_dimms));
 
 	return 0;
-- 
2.49.1