Hi Martin,

On 20 August 2016 at 11:35, Martin Blumenstingl
[off-list ref] wrote:

The Ethernet controller available in Meson8b and GXBB SoCs is a Synopsys
DesignWare MAC IP core which is already supported by the stmmac driver.

In addition to the standard stmmac driver some Meson8b / GXBB specific
registers have to be configured for the PHY clocks. These SoC specific
registers are called PRG_ETHERNET_ADDR0 and PRG_ETHERNET_ADDR1 in the
datasheet.
These registers are not backwards compatible with those on Meson 6b,
which is why a new glue driver is introduced. This worked for many
boards because the bootloader programs the PRG_ETHERNET registers
correctly. Additionally the meson6-dwmac driver only sets bit 1 of
PRG_ETHERNET_ADDR0 which (according to the datasheet) is only used
during reset.

Currently all configuration values can be determined automatically,
based on the configured phy-mode (which is mandatory for the stmmac
driver). If required the tx-delay and the mux clock (so it supports
the MPLL2 clock as well) can be made configurable in the future.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
---
 drivers/net/ethernet/stmicro/stmmac/Makefile       |   2 +-
 .../net/ethernet/stmicro/stmmac/dwmac-meson8b.c    | 329 +++++++++++++++++++++
 2 files changed, 330 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c

<snip>

+static int meson8b_dwmac_probe(struct platform_device *pdev)
+{
+       struct plat_stmmacenet_data *plat_dat;
+       struct stmmac_resources stmmac_res;
+       struct resource *res;
+       struct meson8b_dwmac *dwmac;
+       int ret;
+
+       ret = stmmac_get_platform_resources(pdev, &stmmac_res);
+       if (ret)
+               return ret;
+
+       plat_dat = stmmac_probe_config_dt(pdev, &stmmac_res.mac);
+       if (IS_ERR(plat_dat))
+               return PTR_ERR(plat_dat);
+
+       dwmac = devm_kzalloc(&pdev->dev, sizeof(*dwmac), GFP_KERNEL);
+       if (!dwmac)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+       if (!res)
+               return -ENODEV;
+
+       dwmac->regs = devm_ioremap_resource(&pdev->dev, res);
+       if (IS_ERR(dwmac->regs))
+               return PTR_ERR(dwmac->regs);
+
+       dwmac->pdev = pdev;
+       dwmac->phy_mode = of_get_phy_mode(pdev->dev.of_node);
+       if (dwmac->phy_mode < 0) {
+               dev_err(&pdev->dev, "missing phy-mode property\n");
+               return -EINVAL;
+       }
+
+       ret = meson8b_init_clk(dwmac);
+       if (ret)
+               return ret;
+
+       ret = meson8b_init_prg_eth(dwmac);
+       if (ret)
+               return ret;
+
+       plat_dat->bsp_priv = dwmac;
+
+       platform_set_drvdata(pdev, dwmac);

This will not work. The main stmmac driver already uses the driver_data field.
See: http://lxr.free-electrons.com/source/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c#L3218

+       return stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res);

So calling stmmac_dvr_probe here will overwrite the driver_data field.

+}
+
+static int meson8b_dwmac_remove(struct platform_device *pdev)
+{
+       struct meson8b_dwmac *dwmac = platform_get_drvdata(pdev);
+
+       clk_disable_unprepare(dwmac->m25_div_clk);

Did you test this code? I am pretty sure it will blow up given that
driver_data is not set to what you expect.

To get your meson8b_dwmac struct you must retrieve it from plat_dat->bsp_priv.


I have some code for a helper to retrieve bsp_priv that I have meant
to sent to the ML for a while now.
See: https://github.com/manabian/linux-lpc/commit/c3e155a6e38b9634e4e61aa4eeb4602ede7e44a6

Feel free to add it to your patch set if you want.

Alternatively take a look at the remove function from dwmac-stm32 here:
https://patchwork.ozlabs.org/patch/619816/

+
+       return stmmac_pltfr_remove(pdev);
+}

regards,
Joachim Eastwood