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The devlink param "ts_coarse" doesn't indicate that we get coarse timestamps, but rather that the PHC clock adjusments are coarse as the frequency won't be continuously adjusted. Adjust the devlink parameter name to reflect that. The Coarse terminlogy comes from the dwmac register naming, update the documentation to better explain what the parameter is about. With this change, the parameter can now be adjusted using: devlink dev param set <dev> name phc_coarse_adj value true cmode runtime Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Link: https://patch.msgid.link/20251030182454.182406-1-maxime.chevallier@bootlin.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
41 lines
1.3 KiB
ReStructuredText
41 lines
1.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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=======================================
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stmmac (synopsys dwmac) devlink support
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=======================================
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This document describes the devlink features implemented by the ``stmmac``
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device driver.
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Parameters
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==========
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The ``stmmac`` driver implements the following driver-specific parameters.
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.. list-table:: Driver-specific parameters implemented
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:widths: 5 5 5 85
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* - Name
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- Type
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- Mode
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- Description
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* - ``phc_coarse_adj``
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- Boolean
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- runtime
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- Enable the Coarse timestamping mode, as defined in the DWMAC TRM.
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A detailed explanation of this timestamping mode can be found in the
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Socfpga Functionnal Description [1].
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In Coarse mode, the ptp clock is expected to be fed by a high-precision
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clock that is externally adjusted, and the subsecond increment used for
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timestamping is set to 1/ptp_clock_rate.
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In Fine mode (i.e. Coarse mode == false), the ptp clock frequency is
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continuously adjusted, but the subsecond increment is set to
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2/ptp_clock_rate.
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Coarse mode is suitable for PTP Grand Master operation. If unsure, leave
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the parameter to False.
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[1] https://www.intel.com/content/www/us/en/docs/programmable/683126/21-2/functional-description-of-the-emac.html
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