EDAC, pnd2: Fix Apollo Lake DIMM detection

Non-existent or empty DIMM slots result in error return from
RD_REGP(). But we shouldn't give up on failure.

So long as we find at least one DIMM we can continue.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20170628234407.21521-1-tony.luck@intel.com
Signed-off-by: Borislav Petkov <bp@suse.de>

diff --git a/drivers/edac/pnd2_edac.c b/drivers/edac/pnd2_edac.c
index 407f239553f4f024f549df3849047c0db1940d94..8e599490f6dec2e1c1002742817bd61ded9ecc69 100644 (file)
--- a/drivers/edac/pnd2_edac.c
+++ b/drivers/edac/pnd2_edac.c
@@ -424,16 +424,21 @@ static void dnv_mk_region(char *name, struct region *rp, void *asym)
 
 static int apl_get_registers(void)
 {
+       int ret = -ENODEV;
        int i;
 
        if (RD_REG(&asym_2way, b_cr_asym_2way_mem_region_mchbar))
                return -ENODEV;
 
+       /*
+        * RD_REGP() will fail for unpopulated or non-existent
+        * DIMM slots. Return success if we find at least one DIMM.
+        */
        for (i = 0; i < APL_NUM_CHANNELS; i++)
-               if (RD_REGP(&drp0[i], d_cr_drp0, apl_dports[i]))
-                       return -ENODEV;
+               if (!RD_REGP(&drp0[i], d_cr_drp0, apl_dports[i]))
+                       ret = 0;
 
-       return 0;
+       return ret;
 }
 
 static int dnv_get_registers(void)