| .. 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 |
