[PATCH net-next v2 2/8] net: stmmac: mdio: use same test for MDC clock divisor lookups

["Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>]

Use the same frequency test for all clk_csr value lookups (clock
rate > table rate). This has the side effect that the standard rate
table results in the divider being used for the maximum frequency
for the divider rather than the next higher divider. This still
allows MDC to meet the IEE 802.3 specification, but at a rate closer
to 2.5MHz for these frequencies.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/common.h  |  1 +
 .../net/ethernet/stmicro/stmmac/stmmac_mdio.c | 27 +++++++++----------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index 42a48f655849..e4ce1167ebab 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -257,6 +257,7 @@ struct stmmac_safety_stats {
 	(sizeof(struct stmmac_safety_stats) / sizeof(unsigned long))
 
 /* CSR Frequency Access Defines*/
+#define CSR_F_20M	20000000
 #define CSR_F_35M	35000000
 #define CSR_F_60M	60000000
 #define CSR_F_100M	100000000
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index c4123d2260bd..6292911fb54b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -484,15 +484,16 @@ struct stmmac_clk_rate {
  * clock frequencies.
  */
 static const struct stmmac_clk_rate stmmac_std_csr_to_mdc[] = {
-	{ CSR_F_35M, STMMAC_CSR_20_35M },
-	{ CSR_F_60M, STMMAC_CSR_35_60M },
-	{ CSR_F_100M, STMMAC_CSR_60_100M },
-	{ CSR_F_150M, STMMAC_CSR_100_150M },
-	{ CSR_F_250M, STMMAC_CSR_150_250M },
-	{ CSR_F_300M, STMMAC_CSR_250_300M },
-	{ CSR_F_500M, STMMAC_CSR_300_500M },
-	{ CSR_F_800M, STMMAC_CSR_500_800M },
-	{ },
+	{ CSR_F_800M, ~0 },
+	{ CSR_F_500M, STMMAC_CSR_500_800M },
+	{ CSR_F_300M, STMMAC_CSR_300_500M },
+	{ CSR_F_250M, STMMAC_CSR_250_300M },
+	{ CSR_F_150M, STMMAC_CSR_150_250M },
+	{ CSR_F_100M, STMMAC_CSR_100_150M },
+	{ CSR_F_60M,  STMMAC_CSR_60_100M },
+	{ CSR_F_35M,  STMMAC_CSR_35_60M },
+	{ CSR_F_20M,  STMMAC_CSR_20_35M },
+	{ 0, ~0 },
 };
 
 /* The sun8i clk_csr_i to GMII_Address CR field mapping uses rate as the
@@ -548,13 +549,12 @@ static u32 stmmac_clk_csr_set(struct stmmac_priv *priv)
 	 * divider.
 	 */
 	for (i = 0; stmmac_std_csr_to_mdc[i].rate; i++)
-		if (clk_rate < stmmac_std_csr_to_mdc[i].rate) {
-			value = stmmac_std_csr_to_mdc[i].cr;
+		if (clk_rate > stmmac_std_csr_to_mdc[i].rate)
 			break;
-		}
+	if (stmmac_std_csr_to_mdc[i].cr != (u8)~0)
+		value = stmmac_std_csr_to_mdc[i].cr;
 
 	if (priv->plat->flags & STMMAC_FLAG_HAS_SUN8I) {
-		/* Note the different test - this is intentional. */
 		for (i = 0; stmmac_sun8i_csr_to_mdc[i].rate; i++)
 			if (clk_rate > stmmac_sun8i_csr_to_mdc[i].rate)
 				break;
@@ -562,7 +562,6 @@ static u32 stmmac_clk_csr_set(struct stmmac_priv *priv)
 	}
 
 	if (priv->plat->core_type == DWMAC_CORE_XGMAC) {
-		/* Note the different test - this is intentional. */
 		for (i = 0; stmmac_xgmac_csr_to_mdc[i].rate; i++)
 			if (clk_rate > stmmac_xgmac_csr_to_mdc[i].rate)
 				break;
-- 
2.47.3