From e5aa46ceca003444bd2e7a5f4fd43d5e61499515 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marek=20Beh=C3=BAn?= Date: Wed, 17 Aug 2022 14:35:59 +0200 Subject: [PATCH 95/96] phy: marvell: phy-mvebu-a3700-comphy: Change 2500base-x transmit amplitude MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Change transmit amplitude to 1025 mV for 2500base-x mode. This fixes issue wherein if the 8b/10b encoded packet contains a long enough alternating sequence of bits (010101... or 101010...), which happens if the packet contains a sequence of 'J' or '\xb5' bytes, the packet may be lost due to FCS error. The probability of loss grows with the number of 'J's with default transmit amplitude setting - with 114 'J's the probability is about 50%, with 125 'J's almost 100% of packets are lost. Signed-off-by: Marek Behún --- drivers/phy/marvell/phy-mvebu-a3700-comphy.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/phy/marvell/phy-mvebu-a3700-comphy.c b/drivers/phy/marvell/phy-mvebu-a3700-comphy.c index a4d7d9bd100d..4a18f9ca6d25 100644 --- a/drivers/phy/marvell/phy-mvebu-a3700-comphy.c +++ b/drivers/phy/marvell/phy-mvebu-a3700-comphy.c @@ -68,6 +68,12 @@ #define SPEED_PLL_MASK GENMASK(7, 2) #define SPEED_PLL_VALUE_16 FIELD_PREP(SPEED_PLL_MASK, 0x10) +#define COMPHY_GEN3_SET0 0x0d +#define Gx_TX_AMP_MASK GENMASK(5, 1) +#define Gx_TX_AMP_VALUE(x) FIELD_PREP(Gx_TX_AMP_MASK, x) +#define Gx_TX_AMP_ADJ BIT(6) +#define Gx_TX_AMP_1025MV (Gx_TX_AMP_VALUE(0x12) | Gx_TX_AMP_ADJ) + #define COMPHY_DIG_LOOPBACK_EN 0x23 #define SEL_DATA_WIDTH_MASK GENMASK(11, 10) #define DATA_WIDTH_10BIT FIELD_PREP(SEL_DATA_WIDTH_MASK, 0x0) @@ -746,6 +752,18 @@ mvebu_a3700_comphy_ethernet_power_on(struct mvebu_a3700_comphy_lane *lane) comphy_gbe_phy_init(lane, lane->submode != PHY_INTERFACE_MODE_2500BASEX); + /* + * Fix issue wherein a packet may be lost if it contains a long enough + * sequence of 'J' or '\xb5' bytes. + * This only happens with 2500base-x mode. Fix this by changing transmit + * amplitude to 1025 mV. + */ + if (lane->submode == PHY_INTERFACE_MODE_2500BASEX) { + data = Gx_TX_AMP_1025MV; + mask = Gx_TX_AMP_MASK | Gx_TX_AMP_ADJ; + comphy_lane_reg_set(lane, COMPHY_GEN3_SET0, data, mask); + } + /* * 14. Check the PHY Polarity invert bit */ -- 2.37.2