On Thu, 2022-01-13 at 08:04 +0000, Claudiu.Beznea@xxxxxxxxxxxxx wrote:
> On 12.01.2022 20:11, Robert Hancock wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> > content is safe
> >
> > The GEM controllers on ZynqMP were missing some initialization steps which
> > are required in some cases when using SGMII mode, which uses the PS-GTR
> > transceivers managed by the phy-zynqmp driver.
> >
> > The GEM core appears to need a hardware-level reset in order to work
> > properly in SGMII mode in cases where the GT reference clock was not
> > present at initial power-on. This can be done using a reset mapped to
> > the zynqmp-reset driver in the device tree.
> >
> > Also, when in SGMII mode, the GEM driver needs to ensure the PHY is
> > initialized and powered on when it is initializing.
> >
> > Signed-off-by: Robert Hancock <robert.hancock@xxxxxxxxxx>
> > ---
> > drivers/net/ethernet/cadence/macb_main.c | 47 +++++++++++++++++++++++-
> > 1 file changed, 46 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/cadence/macb_main.c
> > b/drivers/net/ethernet/cadence/macb_main.c
> > index a363da928e8b..65b0360c487a 100644
> > --- a/drivers/net/ethernet/cadence/macb_main.c
> > +++ b/drivers/net/ethernet/cadence/macb_main.c
> > @@ -34,7 +34,9 @@
> > #include <linux/udp.h>
> > #include <linux/tcp.h>
> > #include <linux/iopoll.h>
> > +#include <linux/phy/phy.h>
> > #include <linux/pm_runtime.h>
> > +#include <linux/reset.h>
> > #include "macb.h"
> >
> > /* This structure is only used for MACB on SiFive FU540 devices */
> > @@ -4455,6 +4457,49 @@ static int fu540_c000_init(struct platform_device
> > *pdev)
> > return macb_init(pdev);
> > }
> >
> > +static int zynqmp_init(struct platform_device *pdev)
> > +{
> > + struct net_device *dev = platform_get_drvdata(pdev);
> > + struct macb *bp = netdev_priv(dev);
> > + int ret;
> > +
> > + /* Fully reset GEM controller at hardware level using zynqmp-reset
> > driver,
> > + * if mapped in device tree.
> > + */
> > + ret = device_reset(&pdev->dev);
> > + if (ret) {
> > + dev_err_probe(&pdev->dev, ret, "failed to reset
> > controller");
> > + return ret;
>
> If using old device trees this will fail, right? If yes, you should take
> care this code will also work with old device trees.
I think I had believed device_reset should just return a success without doing
anything if the device tree has no reset defined for the device, but it appears
to get that behavior we should be using device_reset_optional.
>
> Thank you,
> Claudiu Beznea
>
> > + }
> > +
> > + if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII) {
> > + /* Ensure PS-GTR PHY device used in SGMII mode is ready */
> > + struct phy *sgmii_phy = devm_phy_get(&pdev->dev, "sgmii-
> > phy");
> > +
> > + if (IS_ERR(sgmii_phy)) {
> > + ret = PTR_ERR(sgmii_phy);
> > + dev_err_probe(&pdev->dev, ret,
> > + "failed to get PS-GTR PHY\n");
> > + return ret;
> > + }
> > +
> > + ret = phy_init(sgmii_phy);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to init PS-GTR PHY:
> > %d\n",
> > + ret);
> > + return ret;
> > + }
> > +
> > + ret = phy_power_on(sgmii_phy);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to power on PS-GTR PHY:
> > %d\n",
> > + ret);
> > + return ret;
> > + }
> > + }
> > + return macb_init(pdev);
> > +}
> > +
> > static const struct macb_usrio_config sama7g5_usrio = {
> > .mii = 0,
> > .rmii = 1,
> > @@ -4550,7 +4595,7 @@ static const struct macb_config zynqmp_config = {
> > MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH,
> > .dma_burst_length = 16,
> > .clk_init = macb_clk_init,
> > - .init = macb_init,
> > + .init = zynqmp_init,
> > .jumbo_max_len = 10240,
> > .usrio = &macb_default_usrio,
> > };
> > --
> > 2.31.1
> >
