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Diffstat (limited to 'Documentation/networking/devlink/stmmac.rst')
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diff --git a/Documentation/networking/devlink/stmmac.rst b/Documentation/networking/devlink/stmmac.rst new file mode 100644 index 000000000000..47e3ff10bc08 --- /dev/null +++ b/Documentation/networking/devlink/stmmac.rst @@ -0,0 +1,40 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================================= +stmmac (synopsys dwmac) devlink support +======================================= + +This document describes the devlink features implemented by the ``stmmac`` +device driver. + +Parameters +========== + +The ``stmmac`` driver implements the following driver-specific parameters. + +.. list-table:: Driver-specific parameters implemented + :widths: 5 5 5 85 + + * - Name + - Type + - Mode + - Description + * - ``phc_coarse_adj`` + - Boolean + - runtime + - Enable the Coarse timestamping mode, as defined in the DWMAC TRM. + A detailed explanation of this timestamping mode can be found in the + Socfpga Functionnal Description [1]. + + In Coarse mode, the ptp clock is expected to be fed by a high-precision + clock that is externally adjusted, and the subsecond increment used for + timestamping is set to 1/ptp_clock_rate. + + In Fine mode (i.e. Coarse mode == false), the ptp clock frequency is + continuously adjusted, but the subsecond increment is set to + 2/ptp_clock_rate. + + Coarse mode is suitable for PTP Grand Master operation. If unsure, leave + the parameter to False. + + [1] https://www.intel.com/content/www/us/en/docs/programmable/683126/21-2/functional-description-of-the-emac.html |