realtek: adapt RTl931x "digital 2" serdes page calculation

The more we step down into the SerDes deeps the more confusing it
gets. Nevertheless it is not to late to fix a wrong assumption.
Until now it seemed as if the frontend/backend SerDes mapping is
totally without intersection. This is not true.

The backend SerDes mapping is also dependent on the mode. Especially
the proprietary Realtek XSGMII mode stands out from all other
mappings. So fix the descriptions and the calculation of the third
page package (digital 2 aka XSGMII 2).

As it was not yet used it had no impact.

Fixes: a4cbb44c1b ("realtek: convert access to RTL931x analog serdes pages")
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19873
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
index cebf95d8dfe382abd458938a5b7d250c968d7308..5ba7af7fd2199fd3b468dd282cb0798948fb4a8d 100644 (file)
--- a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
+++ b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
@@ -2362,26 +2362,33 @@ static int rtmdio_930x_read_mmd_phy(u32 port, u32 devnum, u32 regnum, u32 *val)
 /*
  * The RTL931x family has 14 "frontend" SerDes that are cascaded. All operations (e.g. reset) work
  * on this frontend view while their registers are distributed over a total of least 26 background
- * SerDes. Two types of SerDes exist:
+ * SerDes with 64 pages and 32 registers. Three types of SerDes exist:
  *
- * An "even" SerDes with numbers 0, 1, 2, 4, 6, 8, 10, 12 works on one background SerDes.
+ * - Serdes 0,1 are "simple" and work on one background serdes.
+ * - "Even" SerDes with numbers 2, 4, 6, 8, 10, 12 work on two background SerDes. One analog and
+ *   one digital.
+ * - "Odd" SerDes with numbers 3, 5, 7, 9, 11, 13 work on a total of 3 background SerDes (one analog
+ *   and two digital)
+ *
+ * This maps to:
  *
- * The "odd" SerDes with numbers 3, 5, 7, 9, 11 & 13 SerDes consist of a total of 3 background
- * SerDes (one analog and two XSGMII) each with its own page/register set. So it gives this
- * mapping:
-
  * Frontend SerDes  |  0  1  2  3  4  5  6  7  8  9 10 11 12 13
  * -----------------+------------------------------------------
  * Backend SerDes 1 |  0  1  2  3  6  7 10 11 14 15 18 19 22 23
  * Backend SerDes 2 |  0  1  2  4  6  8 10 12 14 16 18 20 22 24
- * Backend SerDes 3 |  0  1  2  5  6  9 10 13 14 17 18 21 22 25
+ * Backend SerDes 3 |  0  1  3  5  7  9 11 13 15 17 19 21 23 25
+ *
+ * Note: In Realtek proprietary XSGMII mode (10G pumped SGMII) the frontend SerDes works on the
+ * two digital SerDes while in all other modes it works on the analog and the first digital SerDes.
+ * Overlapping (e.g. backend SerDes 7 can be analog or digital 2) is avoided by the existing
+ * hardware designs.
  *
  * Align this for readability by simulating a total of 576 pages and mix them as follows.
  *
  * frontend page               "even" frontend SerDes          "odd" frontend SerDes
  * page 0x000-0x03f (analog):  page 0x000-0x03f back SDS       page 0x000-0x03f back SDS
- * page 0x100-0x13f (XSGMII1): page 0x000-0x03f back SDS       page 0x000-0x03f back SDS+1
- * page 0x200-0x23f (XSGMII2): page 0x000-0x03f back SDS       page 0x000-0x03f back SDS+2
+ * page 0x100-0x13f (digi 1):  page 0x000-0x03f back SDS       page 0x000-0x03f back SDS+1
+ * page 0x200-0x23f (digi 2):  page 0x000-0x03f back SDS+1     page 0x000-0x03f back SDS+2
  */ 
 
 static int rtmdio_931x_get_backing_sds(u32 sds, u32 page)
@@ -2392,8 +2399,12 @@ static int rtmdio_931x_get_backing_sds(u32 sds, u32 page)
        if (page & 0xc0)
                return -EINVAL; /* hole */
 
-       if ((sds & 1) && (sds != 1))
-               back += (page >> 8); /* distribute "odd" to 3 background SerDes */
+       if (sds >= 2) {
+               if (sds & 1)
+                       back += (page >> 8); /* distribute "odd" to 3 background SerDes */
+               else
+                       back += (page >> 9); /* distribute "even" to 2 background SerDes */
+       }
 
        return back;
 }