e1000e: Fix the max snoop/no-snoop latency for 10M

BugLink: https://bugs.launchpad.net/bugs/1944610
[ Upstream commit 44a13a5d99c71bf9e1676d9e51679daf4d7b3d73 ]

We should decode the latency and the max_latency before directly compare.
The latency should be presented as lat_enc = scale x value:
lat_enc_d = (lat_enc & 0x0x3ff) x (1U << (5*((max_ltr_enc & 0x1c00)
>> 10)))

Fixes: cf8fb73c23aa ("e1000e: add support for LTR on I217/I218")
Suggested-by: Yee Li <seven.yi.lee@gmail.com>
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index dc2a570f77425b7d1a8d031ba9bd403abc0ce614..88d2183db9093e168f12bf6f684da2767ec6a40e 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -1006,6 +1006,8 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
 {
        u32 reg = link << (E1000_LTRV_REQ_SHIFT + E1000_LTRV_NOSNOOP_SHIFT) |
            link << E1000_LTRV_REQ_SHIFT | E1000_LTRV_SEND;
+       u16 max_ltr_enc_d = 0;  /* maximum LTR decoded by platform */
+       u16 lat_enc_d = 0;      /* latency decoded */
        u16 lat_enc = 0;        /* latency encoded */
 
        if (link) {
@@ -1059,7 +1061,17 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
                                     E1000_PCI_LTR_CAP_LPT + 2, &max_nosnoop);
                max_ltr_enc = max_t(u16, max_snoop, max_nosnoop);
 
-               if (lat_enc > max_ltr_enc)
+               lat_enc_d = (lat_enc & E1000_LTRV_VALUE_MASK) *
+                            (1U << (E1000_LTRV_SCALE_FACTOR *
+                            ((lat_enc & E1000_LTRV_SCALE_MASK)
+                            >> E1000_LTRV_SCALE_SHIFT)));
+
+               max_ltr_enc_d = (max_ltr_enc & E1000_LTRV_VALUE_MASK) *
+                                (1U << (E1000_LTRV_SCALE_FACTOR *
+                                ((max_ltr_enc & E1000_LTRV_SCALE_MASK)
+                                >> E1000_LTRV_SCALE_SHIFT)));
+
+               if (lat_enc_d > max_ltr_enc_d)
                        lat_enc = max_ltr_enc;
        }
 

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.h b/drivers/net/ethernet/intel/e1000e/ich8lan.h
index 1502895eb45ddd996c9f75aefc4ac29ea61e16a5..e757896287eba1256d3838a7db8af4048c4b2347 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.h
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.h
@@ -274,8 +274,11 @@
 
 /* Latency Tolerance Reporting */
 #define E1000_LTRV                     0x000F8
+#define E1000_LTRV_VALUE_MASK          0x000003FF
 #define E1000_LTRV_SCALE_MAX           5
 #define E1000_LTRV_SCALE_FACTOR                5
+#define E1000_LTRV_SCALE_SHIFT         10
+#define E1000_LTRV_SCALE_MASK          0x00001C00
 #define E1000_LTRV_REQ_SHIFT           15
 #define E1000_LTRV_NOSNOOP_SHIFT       16
 #define E1000_LTRV_SEND                        (1 << 30)