[FAQ] [参考译文] [常见问题解答] TDA4VM：如何在 SDK 8.6及更低版本的本机 Linux 驱动程序中修复 CPSW 端口8上的通信故障。

From 0badc8f20da335c699895cb92353e10f9f6dc109 Mon Sep 17 00:00:00 2001
From: Tanmay Patil <t-patil@ti.com>
Date: Mon, 24 Apr 2023 14:28:24 +0530
Subject: [PATCH] net: ethernet: ti: cpsw_ale: Fix ale field set and get

CPSW ALE has 75 bit ALE entries which is are stored in 3
32 bit words. With Read/Write using cpsw_ale_get_field()/
cpsw_ale_set_field(), the function assumes that the field
will be strictly contained within one word. This is not
the case and ALE field entries can span upto two words.

This commit adds the support for reading/writing ALE
fields which span two words.

Signed-off-by: Tanmay Patil <t-patil@ti.com>
---
 drivers/net/ethernet/ti/cpsw_ale.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw_ale.c b/drivers/net/ethernet/ti/cpsw_ale.c
index 6d60373d15e0..dc8d6f8e7dda 100644
--- a/drivers/net/ethernet/ti/cpsw_ale.c
+++ b/drivers/net/ethernet/ti/cpsw_ale.c
@@ -106,23 +106,35 @@ struct cpsw_ale_dev_id {
 
 static inline int cpsw_ale_get_field(u32 *ale_entry, u32 start, u32 bits)
 {
-	int idx;
+	int idx, idx2;
+	u32 hi_val = 0;
 
 	idx    = start / 32;
+	idx2 = (start + bits - 1) / 32;
+	if (idx != idx2) {
+		idx2 = 2 - idx2; /* flip */
+		hi_val = ale_entry[idx2] << ((idx2 * 32) - start);
+	}
 	start -= idx * 32;
 	idx    = 2 - idx; /* flip */
-	return (ale_entry[idx] >> start) & BITMASK(bits);
+	return (hi_val + (ale_entry[idx] >> start)) & BITMASK(bits);
 }
 
 static inline void cpsw_ale_set_field(u32 *ale_entry, u32 start, u32 bits,
 				      u32 value)
 {
-	int idx;
+	int idx, idx2;
 
 	value &= BITMASK(bits);
-	idx    = start / 32;
+	idx = start / 32;
+	idx2 = (start + bits - 1) / 32;
+	if (idx != idx2) {
+		idx2 = 2 - idx2; /* flip */
+		ale_entry[idx2] &= ~(BITMASK(bits + start - (idx2 * 32)));
+		ale_entry[idx2] |= (value >> ((idx2 * 32) - start));
+	}
 	start -= idx * 32;
-	idx    = 2 - idx; /* flip */
+	idx = 2 - idx; /* flip */
 	ale_entry[idx] &= ~(BITMASK(bits) << start);
 	ale_entry[idx] |=  (value << start);
 }
-- 
2.25.1