linux-kernel - [PATCH v3 6/6] EDAC/amd64: Adjust printed Chip Select sizes when interleaved

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Message-ID: <20190228153558.127292-6-Yazen.Ghannam@amd.com>
Date:   Thu, 28 Feb 2019 15:36:12 +0000
From:   "Ghannam, Yazen" <Yazen.Ghannam@....com>
To:     "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>
CC:     "Ghannam, Yazen" <Yazen.Ghannam@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bp@...en8.de" <bp@...en8.de>
Subject: [PATCH v3 6/6] EDAC/amd64: Adjust printed Chip Select sizes when
 interleaved

From: Yazen Ghannam <yazen.ghannam@....com>

AMD systems may support Chip Select interleaving. However, on Family
17h+ this was not taken into account when printing the Chip Select
sizes.

Add support to detect if Chip Selects are interleaved on Family 17h+,
and adjust the sizes accordingly.

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
---
Link:
https://lkml.kernel.org/r/20190226172532.12924-6-Yazen.Ghannam@amd.com

v2->v3:
* Change Fam17h+ to Family 17h+ in commit message.

v1->v2:
* No change.

 drivers/edac/amd64_edac.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index c05995685cfa..1b9cf916b2d0 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -784,6 +784,22 @@ static void debug_dump_dramcfg_low(struct amd64_pvt *pvt, u32 dclr, int chan)
 		 (dclr & BIT(15)) ?  "yes" : "no");
 }
 
+/*
+ * The Address Mask should be a contiguous set of bits in the non-interleaved
+ * case. So to check for CS interleaving, find the most- and least-significant
+ * bits of the mask, generate a contiguous bitmask, and compare the two.
+ */
+static bool f17_cs_interleaved(struct amd64_pvt *pvt, u8 ctrl, int cs)
+{
+	u32 mask = pvt->csels[ctrl].csmasks[cs >> 1];
+	u32 msb = fls(mask) - 1, lsb = ffs(mask) - 1;
+	u32 test_mask = GENMASK(msb, lsb);
+
+	edac_dbg(1, "mask=0x%08x test_mask=0x%08x\n", mask, test_mask);
+
+	return mask ^ test_mask;
+}
+
 static void debug_display_dimm_sizes_df(struct amd64_pvt *pvt, u8 ctrl)
 {
 	int dimm, size0, size1, cs0, cs1;
@@ -800,8 +816,19 @@ static void debug_display_dimm_sizes_df(struct amd64_pvt *pvt, u8 ctrl)
 		size1 = 0;
 		cs1 = dimm * 2 + 1;
 
-		if (csrow_enabled(cs1, ctrl, pvt))
-			size1 = pvt->ops->dbam_to_cs(pvt, ctrl, 0, cs1);
+		if (csrow_enabled(cs1, ctrl, pvt)) {
+			/*
+			 * CS interleaving is only supported if both CSes have
+			 * the same amount of memory. Because they are
+			 * interleaved, it will look like both CSes have the
+			 * full amount of memory. Save the size for both as
+			 * half the amount we found on CS0, if interleaved.
+			 */
+			if (f17_cs_interleaved(pvt, ctrl, cs1))
+				size1 = size0 = (size0 >> 1);
+			else
+				size1 = pvt->ops->dbam_to_cs(pvt, ctrl, 0, cs1);
+		}
 
 		amd64_info(EDAC_MC ": %d: %5dMB %d: %5dMB\n",
 				cs0,	size0,
-- 
2.17.1