[PATCH v2] stmmac: avoid ipq806x constant overflow warning
Arnd Bergmann
arnd at arndb.de
Thu Nov 12 13:03:40 PST 2015
Building dwmac-ipq806x on a 64-bit architecture produces a harmless
warning from gcc:
stmmac/dwmac-ipq806x.c: In function 'ipq806x_gmac_probe':
include/linux/bitops.h:6:19: warning: overflow in implicit constant conversion [-Woverflow]
val = QSGMII_PHY_CDR_EN |
stmmac/dwmac-ipq806x.c:333:8: note: in expansion of macro 'QSGMII_PHY_CDR_EN'
#define QSGMII_PHY_CDR_EN BIT(0)
#define BIT(nr) (1UL << (nr))
This is a result of the type conversion rules in C, when we take the
logical OR of multiple different types. In particular, we have
and unsigned long
QSGMII_PHY_CDR_EN == BIT(0) == (1ul << 0) == 0x0000000000000001ul
and a signed int
0xC << QSGMII_PHY_TX_DRV_AMP_OFFSET == 0xc0000000
which together gives a signed long value
0xffffffffc0000001l
and when this is passed into a function that takes an unsigned int type,
gcc warns about the signed overflow and the loss of the upper 32-bits that
are all ones.
This patch adds 'ul' type modifiers to the literal numbers passed in
here, so now the expression remains an 'unsigned long' with the upper
bits all zero, and that avoids the signed overflow and the warning.
Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Fixes: b1c17215d718 ("stmmac: add ipq806x glue layer")
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c
index 9d89bdbf029f..82de68b1a452 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c
@@ -337,11 +337,11 @@ static int ipq806x_gmac_probe(struct platform_device *pdev)
QSGMII_PHY_RX_SIGNAL_DETECT_EN |
QSGMII_PHY_TX_DRIVER_EN |
QSGMII_PHY_QSGMII_EN |
- 0x4 << QSGMII_PHY_PHASE_LOOP_GAIN_OFFSET |
- 0x3 << QSGMII_PHY_RX_DC_BIAS_OFFSET |
- 0x1 << QSGMII_PHY_RX_INPUT_EQU_OFFSET |
- 0x2 << QSGMII_PHY_CDR_PI_SLEW_OFFSET |
- 0xC << QSGMII_PHY_TX_DRV_AMP_OFFSET);
+ 0x4ul << QSGMII_PHY_PHASE_LOOP_GAIN_OFFSET |
+ 0x3ul << QSGMII_PHY_RX_DC_BIAS_OFFSET |
+ 0x1ul << QSGMII_PHY_RX_INPUT_EQU_OFFSET |
+ 0x2ul << QSGMII_PHY_CDR_PI_SLEW_OFFSET |
+ 0xCul << QSGMII_PHY_TX_DRV_AMP_OFFSET);
}
plat_dat->has_gmac = true;
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