imx6ul: fec: stuck on ifup after ifdown

imx6ul: fec: stuck on ifup after ifdown

[Manni Stefano]

Hi,

on a custom board based on a i.MX6UL using barebox v2020.08.1 'ifup eth0'
invoked after 'ifdown eth0' stucks forever.

Have you ever experienced something similar?

Snippet from my device tree:

        &fec1 {
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_enet1>;
                phy-mode = "rmii";
                phy-handle = <&ethphy1>;
                status = "okay";
                phy-reset-gpios = <&gpio1 23 GPIO_ACTIVE_LOW>;
                phy-reset-duration = <1>;

                mdio {
                        #address-cells = <1>;
                        #size-cells = <0>;

                        clock-frequency = <5000000>;
                        ethphy1: ethernet-phy@1 {
                                compatible = "ethernet-phy-ieee802.3-c22";
                                reg = <0>;
                                max-speed = <100>;
                                interrupt-parent = <&gpio1>;
                                interrupts = <22 IRQ_TYPE_LEVEL_LOW>;
                        };
                };
        };

        pinctrl_enet1: enet1grp {
                fsl,pins = <
                        MX6UL_PAD_GPIO1_IO06__ENET1_MDIO        0x1b0b0
                        MX6UL_PAD_GPIO1_IO07__ENET1_MDC         0x1b0b0
                        MX6UL_PAD_ENET1_TX_DATA0__ENET1_TDATA00 0x1b0b0
                        MX6UL_PAD_ENET1_TX_DATA1__ENET1_TDATA01 0x1b0b0
                        MX6UL_PAD_ENET1_TX_EN__ENET1_TX_EN      0x1b0b0
                        MX6UL_PAD_ENET1_TX_CLK__ENET1_REF_CLK1  0x4001b031
                        MX6UL_PAD_ENET1_RX_DATA0__ENET1_RDATA00 0x1b0b0
                        MX6UL_PAD_ENET1_RX_DATA1__ENET1_RDATA01 0x1b0b0
                        MX6UL_PAD_ENET1_RX_EN__ENET1_RX_EN      0x1b0b0
                        MX6UL_PAD_ENET1_RX_ER__ENET1_RX_ER      0x1b0b0
                        MX6UL_PAD_UART2_RTS_B__GPIO1_IO23       0x1b0b0
                        MX6UL_PAD_UART2_CTS_B__GPIO1_IO22       0x1b0b0
                >;
        };

Best,
Stefano


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Re: imx6ul: fec: stuck on ifup after ifdown

[Sascha Hauer]

Hi Stefano,

On Mon, Oct 05, 2020 at 02:43:15PM +0200, Manni Stefano wrote:
> Hi,
> 
> on a custom board based on a i.MX6UL using barebox v2020.08.1 'ifup eth0'
> invoked after 'ifdown eth0' stucks forever.
> 
> Have you ever experienced something similar?

I can confirm the same happens here on an i.MX6q board on current
master. I don't know what's happening here. The last thing I see is that
fec_tx_task_enable() is entered. Strange enough the same works on i.MX53
whereas on i.MX8M I get "ERROR: eth0: transmission timeout" on the
second ifup.

This is really strange. It seems fec_tx_task_enable() brings down the
whole SoC, but on the other hand the FEC works properly in a chainloaded
barebox, which should - from the view of the ethernet controller - be
the same as a repeated ifup/ifdown sequence.

I have no idea what is going wrong here.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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Re: imx6ul: fec: stuck on ifup after ifdown

[Lucas Stach]

On Mo, 2020-10-05 at 17:17 +0200, Sascha Hauer wrote:
> Hi Stefano,
> 
> On Mon, Oct 05, 2020 at 02:43:15PM +0200, Manni Stefano wrote:
> > Hi,
> > 
> > on a custom board based on a i.MX6UL using barebox v2020.08.1 'ifup eth0'
> > invoked after 'ifdown eth0' stucks forever.
> > 
> > Have you ever experienced something similar?
> 
> I can confirm the same happens here on an i.MX6q board on current
> master. I don't know what's happening here. The last thing I see is that
> fec_tx_task_enable() is entered. Strange enough the same works on i.MX53
> whereas on i.MX8M I get "ERROR: eth0: transmission timeout" on the
> second ifup.
> 
> This is really strange. It seems fec_tx_task_enable() brings down the
> whole SoC, but on the other hand the FEC works properly in a chainloaded
> barebox, which should - from the view of the ethernet controller - be
> the same as a repeated ifup/ifdown sequence.

There is a crucial difference between the two things: in a chainloaded
Barebox we go through the FEC driver probe again, before doing the next
ifup. When going through probe a full reset of the FEC peripheral is
done.

Regards,
Lucas


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Re: imx6ul: fec: stuck on ifup after ifdown

[Sascha Hauer]

On Tue, Oct 06, 2020 at 10:44:24AM +0200, Lucas Stach wrote:
> On Mo, 2020-10-05 at 17:17 +0200, Sascha Hauer wrote:
> > Hi Stefano,
> > 
> > On Mon, Oct 05, 2020 at 02:43:15PM +0200, Manni Stefano wrote:
> > > Hi,
> > > 
> > > on a custom board based on a i.MX6UL using barebox v2020.08.1 'ifup eth0'
> > > invoked after 'ifdown eth0' stucks forever.
> > > 
> > > Have you ever experienced something similar?
> > 
> > I can confirm the same happens here on an i.MX6q board on current
> > master. I don't know what's happening here. The last thing I see is that
> > fec_tx_task_enable() is entered. Strange enough the same works on i.MX53
> > whereas on i.MX8M I get "ERROR: eth0: transmission timeout" on the
> > second ifup.
> > 
> > This is really strange. It seems fec_tx_task_enable() brings down the
> > whole SoC, but on the other hand the FEC works properly in a chainloaded
> > barebox, which should - from the view of the ethernet controller - be
> > the same as a repeated ifup/ifdown sequence.
> 
> There is a crucial difference between the two things: in a chainloaded
> Barebox we go through the FEC driver probe again, before doing the next
> ifup. When going through probe a full reset of the FEC peripheral is
> done.

Actually I thought there is a full FEC reset in fec_halt():

	writel(readl(fec->regs + FEC_X_CNTRL) | FEC_ECNTRL_RESET,
		fec->regs + FEC_X_CNTRL);

I only saw the FEC_ECNTRL_RESET bit but didn't realize this goes to a
completely unrelated register. We should have a FEC_X_CNTRL_GTS define
for this.

Given that, the fec_halt/fec_init path really looks quite different from
the fec_probe/fec_init path.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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