Thread (23 messages) flat view 23 messages, 5 authors, 2026-02-17
STALE205d

[PATCH RFC net-next 2/9] net: stmmac: qcom-ethqos: remove register field value obfuscations

From: Russell King (Oracle) <hidden>
Date: 2026-02-12 00:17:59
Also in: imx, linux-arm-kernel, linux-arm-msm
Subsystem: networking drivers, qualcomm ethqos ethernet driver, stmmac ethernet driver, the rest · Maintainers: Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Mohd Ayaan Anwar, Maxime Chevallier, Linus Torvalds

Convert the register field values to something more human readable.

For example, using (BIT(29) | BIT(27)) to update a register field that
consists of bits 29:27 is an obfuscated way of writing decimal 5 for
this field. The comment above needs to explain that this value is 5.

Worse still is BIT(12) | GENMASK(9, 8), which is used to hide the
decimal value 19 for the bitfield 16:8.

Fix these, and a few others by using FIELD_PREP(). While it means we
have bare numeric constants, this is more preferable than having the
obfuscation.

Signed-off-by: Russell King (Oracle) <redacted>
---
 .../stmicro/stmmac/dwmac-qcom-ethqos.c        | 23 ++++++++++++-------
 1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
index 690bd5c7e1a6..50b95fd19f9d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -361,10 +361,12 @@ static int ethqos_dll_configure(struct qcom_ethqos *ethqos)
 			      SDCC_HC_REG_DLL_CONFIG2);
 
 		rgmii_updatel(ethqos, SDCC_DLL_CONFIG2_MCLK_FREQ_CALC,
-			      0x1A << 10, SDCC_HC_REG_DLL_CONFIG2);
+			      FIELD_PREP(SDCC_DLL_CONFIG2_MCLK_FREQ_CALC, 26),
+			      SDCC_HC_REG_DLL_CONFIG2);
 
 		rgmii_updatel(ethqos, SDCC_DLL_CONFIG2_DDR_TRAFFIC_INIT_SEL,
-			      BIT(2), SDCC_HC_REG_DLL_CONFIG2);
+			      FIELD_PREP(SDCC_DLL_CONFIG2_DDR_TRAFFIC_INIT_SEL,
+					 1), SDCC_HC_REG_DLL_CONFIG2);
 
 		rgmii_setmask(ethqos, SDCC_DLL_CONFIG2_DDR_TRAFFIC_INIT_SW,
 			      SDCC_HC_REG_DLL_CONFIG2);
@@ -425,11 +427,13 @@ static int ethqos_rgmii_macro_init(struct qcom_ethqos *ethqos, int speed)
 		if (ethqos->has_emac_ge_3) {
 			/* 0.9 ns */
 			rgmii_updatel(ethqos, SDCC_DDR_CONFIG_PRG_RCLK_DLY,
-				      115, SDCC_HC_REG_DDR_CONFIG);
+				      FIELD_PREP(SDCC_DDR_CONFIG_PRG_RCLK_DLY,
+						 115), SDCC_HC_REG_DDR_CONFIG);
 		} else {
 			/* 1.8 ns */
 			rgmii_updatel(ethqos, SDCC_DDR_CONFIG_PRG_RCLK_DLY,
-				      57, SDCC_HC_REG_DDR_CONFIG);
+				      FIELD_PREP(SDCC_DDR_CONFIG_PRG_RCLK_DLY,
+						 57), SDCC_HC_REG_DDR_CONFIG);
 		}
 		rgmii_setmask(ethqos, SDCC_DDR_CONFIG_PRG_DLY_EN,
 			      SDCC_HC_REG_DDR_CONFIG);
@@ -451,7 +455,8 @@ static int ethqos_rgmii_macro_init(struct qcom_ethqos *ethqos, int speed)
 		rgmii_updatel(ethqos, RGMII_CONFIG2_TX_CLK_PHASE_SHIFT_EN,
 			      phase_shift, RGMII_IO_MACRO_CONFIG2);
 		rgmii_updatel(ethqos, RGMII_CONFIG_MAX_SPD_PRG_2,
-			      BIT(6), RGMII_IO_MACRO_CONFIG);
+			      FIELD_PREP(RGMII_CONFIG_MAX_SPD_PRG_2, 1),
+			      RGMII_IO_MACRO_CONFIG);
 		rgmii_clrmask(ethqos, RGMII_CONFIG2_RSVD_CONFIG15,
 			      RGMII_IO_MACRO_CONFIG2);
 
@@ -464,7 +469,8 @@ static int ethqos_rgmii_macro_init(struct qcom_ethqos *ethqos, int speed)
 
 		/* Write 0x5 to PRG_RCLK_DLY_CODE */
 		rgmii_updatel(ethqos, SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY_CODE,
-			      (BIT(29) | BIT(27)), SDCC_HC_REG_DDR_CONFIG);
+			      FIELD_PREP(SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY_CODE,
+					 5), SDCC_HC_REG_DDR_CONFIG);
 		rgmii_setmask(ethqos, SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY,
 			      SDCC_HC_REG_DDR_CONFIG);
 		rgmii_setmask(ethqos, SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY_EN,
@@ -487,7 +493,7 @@ static int ethqos_rgmii_macro_init(struct qcom_ethqos *ethqos, int speed)
 		rgmii_updatel(ethqos, RGMII_CONFIG2_TX_CLK_PHASE_SHIFT_EN,
 			      phase_shift, RGMII_IO_MACRO_CONFIG2);
 		rgmii_updatel(ethqos, RGMII_CONFIG_MAX_SPD_PRG_9,
-			      BIT(12) | GENMASK(9, 8),
+			      FIELD_PREP(RGMII_CONFIG_MAX_SPD_PRG_9, 19),
 			      RGMII_IO_MACRO_CONFIG);
 		rgmii_clrmask(ethqos, RGMII_CONFIG2_RSVD_CONFIG15,
 			      RGMII_IO_MACRO_CONFIG2);
@@ -499,7 +505,8 @@ static int ethqos_rgmii_macro_init(struct qcom_ethqos *ethqos, int speed)
 				      RGMII_IO_MACRO_CONFIG2);
 		/* Write 0x5 to PRG_RCLK_DLY_CODE */
 		rgmii_updatel(ethqos, SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY_CODE,
-			      (BIT(29) | BIT(27)), SDCC_HC_REG_DDR_CONFIG);
+			      FIELD_PREP(SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY_CODE,
+					 5), SDCC_HC_REG_DDR_CONFIG);
 		rgmii_setmask(ethqos, SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY,
 			      SDCC_HC_REG_DDR_CONFIG);
 		rgmii_setmask(ethqos, SDCC_DDR_CONFIG_EXT_PRG_RCLK_DLY_EN,
-- 
2.47.3
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