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In industrial environments where 10BaseT1L PHYs are replacing existing
field bus systems like CAN, it's often essential to retain the existing
cable infrastructure. After installation, collecting metrics such as
cable length is crucial for assessing the quality of the infrastructure.
Traditionally, TDR (Time Domain Reflectometry) is used for this purpose.
However, TDR requires interrupting the link, and if the link partner
remains active, the TDR measurement will fail.
Unlike multi-pair systems, where TDR can be attempted during the MDI-X
switching window, 10BaseT1L systems face greater challenges. The TDR
sequence on 10BaseT1L is longer and coincides with uninterrupted
autonegotiation pulses, making TDR impossible when the link partner is
active.
The DP83TD510 PHY provides an alternative through ALCD (Active Link
Cable Diagnostics), which allows for cable length measurement without
disrupting an active link. Since a live link indicates no short or open
cable states, ALCD can be used effectively to gather cable length
information.
Enhance the dp83td510 driver by:
- Leveraging ALCD to measure cable length when the link is active.
- Bypassing TDR when a link is detected, as ALCD provides the required
information without disruption.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20240822120703.1393130-4-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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This patch implements the TDR test procedure as described in
"Application Note DP83TD510E Cable Diagnostics Toolkit revC", section 3.2.
The procedure was tested with "draka 08 signalkabel 2x0.8mm". The reported
cable length was 5 meters more for each 20 meters of actual cable length.
For instance, a 20-meter cable showed as 25 meters, and a 40-meter cable
showed as 50 meters. Since other parts of the diagnostics provided by this
PHY (e.g., Active Link Cable Diagnostics) require accurate cable
characterization to provide proper results, this tuning can be implemented
in a separate patch/interface.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
changes v2:
- add comments
- change post silence time to 1000ms
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20240712152848.2479912-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Fix an issue where the kernel would stall during netboot, showing the
"sched: RT throttling activated" message. This stall was triggered by
the behavior of the mii_interrupt bit (Bit 7 - DP83TD510E_STS_MII_INT)
in the DP83TD510E's PHY_STS Register (Address = 0x10). The DP83TD510E
datasheet (2020) states that the bit clears on write, however, in
practice, the bit clears on read.
This discrepancy had significant implications on the driver's interrupt
handling. The PHY_STS Register was used by handle_interrupt() to check
for pending interrupts and by read_status() to get the current link
status. The call to read_status() was unintentionally clearing the
mii_interrupt status bit without deasserting the IRQ pin, causing
handle_interrupt() to miss other pending interrupts. This issue was most
apparent during netboot.
The fix refrains from using the PHY_STS Register for interrupt handling.
Instead, we now solely rely on the INTERRUPT_REG_1 Register (Address =
0x12) and INTERRUPT_REG_2 Register (Address = 0x13) for this purpose.
These registers directly influence the IRQ pin state and are latched
high until read.
Note: The INTERRUPT_REG_2 Register (Address = 0x13) exists and can also
be used for interrupt handling, specifically for "Aneg page received
interrupt" and "Polarity change interrupt". However, these features are
currently not supported by this driver.
Fixes: 165cd04fe253 ("net: phy: dp83td510: Add support for the DP83TD510 Ethernet PHY")
Cc: <stable@vger.kernel.org>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230621043848.3806124-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Convert MSE (mean-square error) values to SNR and split it SQI (Signal Quality
Indicator) ranges. The used ranges are taken from "OPEN ALLIANCE - Advanced
diagnostic features for 100BASE-T1 automotive Ethernet PHYs"
specification.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220620115601.2035452-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The DP83TD510E is an ultra-low power Ethernet physical layer transceiver
that supports 10M single pair cable.
This driver was tested with NXP SJA1105, STMMAC and ASIX AX88772B USB Ethernet
controller.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
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