[BUG]odroid-c2 does not hotplug usb-devices

[Otto Meier]

Hi Martin,

i think the the u-boot fix made the new u-boot for me usable.
Because i boot from emmc it fixes a long standing problem since 2020.04
in not booting from emmc.
The latest uboot, booting from emmc before the fix was 2020.04, but this 
old uboot does not funktion well
(hotpluging and others) with newer kernel (5.8.10 was the latest i new 
of). Therefore
the latest Uboot initialized the kernel in a way that new kernels work 
again.

I haven't run kernel in between, with newer uboots like 2020.07 or 
2020.10, because they din't boot
from emmc.

so if the uboot patch is the real reason, i don't think.

best regrads

Otto

Am 19.12.20 um 23:31 schrieb Martin Blumenstingl:
> Hi Anand,
>
> On Sat, Dec 19, 2020 at 8:53 PM Anand Moon <linux.amoon at gmail.com> wrote:
> [...]
>> I was also looking into this issue so I made some changes in the
>> phy driver to resolve the issue. Plz share your thoughts on the changes below.
> first I have some questions :-)
> 1. do you see the same problem that Otto sees? this means: a) USB
> hotplug works as long as at least one device is plugged in at boot b)
> (if I understand Otto correctly then) it breaks once all USB devices
> have been removed
> 2. does the mainline u-boot patch mentioned by Otto fix the problem
> for you? according to him it fixes the problem and he did not have to
> modify the USB PHY driver
>
>> amoon at ThinkPad-T440s:~/mainline/linux-aml-5.y-devel$ git diff
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
>> b/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
>> index 7c029f552a23..363dd2ac17e6 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
>> +++ b/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
>> @@ -20,6 +20,7 @@ usb0_phy: phy at c0000000 {
>>                          #phy-cells = <0>;
>>                          reg = <0x0 0xc0000000 0x0 0x20>;
>>                          resets = <&reset RESET_USB_OTG>;
>> +                       reset-names = "phy-reset";
>>                          clocks = <&clkc CLKID_USB>, <&clkc CLKID_USB0>;
>>                          clock-names = "usb_general", "usb";
>>                          status = "disabled";
>> @@ -30,6 +31,7 @@ usb1_phy: phy at c0000020 {
>>                          #phy-cells = <0>;
>>                          reg = <0x0 0xc0000020 0x0 0x20>;
>>                          resets = <&reset RESET_USB_OTG>;
>> +                       reset-names = "phy-reset";
>>                          clocks = <&clkc CLKID_USB>, <&clkc CLKID_USB1>;
>>                          clock-names = "usb_general", "usb";
>>                          status = "disabled";
> I don't see why the above two changes are needed
> see my comment about of_reset_control_get_shared below
>
>> diff --git a/drivers/phy/amlogic/phy-meson8b-usb2.c
>> b/drivers/phy/amlogic/phy-meson8b-usb2.c
>> index 03c061dd5f0d..31523becc878 100644
>> --- a/drivers/phy/amlogic/phy-meson8b-usb2.c
>> +++ b/drivers/phy/amlogic/phy-meson8b-usb2.c
>> @@ -143,14 +143,6 @@ static int phy_meson8b_usb2_power_on(struct phy *phy)
>>          u32 reg;
>>          int ret;
>>
>> -       if (!IS_ERR_OR_NULL(priv->reset)) {
>> -               ret = reset_control_reset(priv->reset);
>> -               if (ret) {
>> -                       dev_err(&phy->dev, "Failed to trigger USB reset\n");
>> -                       return ret;
>> -               }
>> -       }
>> -
>>          ret = clk_prepare_enable(priv->clk_usb_general);
>>          if (ret) {
>>                  dev_err(&phy->dev, "Failed to enable USB general clock\n");
>> @@ -222,9 +214,23 @@ static int phy_meson8b_usb2_power_off(struct phy *phy)
>>          return 0;
>>   }
>>
>> +static int phy_meson8b_usb2_reset(struct phy *phy)
>> +{
>> +       struct phy_meson8b_usb2_priv *priv = phy_get_drvdata(phy);
>> +
>> +       if (priv->reset) {
>> +               reset_control_assert(priv->reset);
>> +               udelay(10);
>> +               reset_control_deassert(priv->reset);
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>>   static const struct phy_ops phy_meson8b_usb2_ops = {
>>          .power_on       = phy_meson8b_usb2_power_on,
>>          .power_off      = phy_meson8b_usb2_power_off,
>> +       .reset          = phy_meson8b_usb2_reset,
>>          .owner          = THIS_MODULE,
>>   };
> I tested this on my Odroid-C1: phy_meson8b_usb2_reset is never called
> after checking the dwc2 code this is expected: only in one very
> specific case the dwc2 driver calls phy_reset
> can you please find out how phy_meson8b_usb2_reset is called in your kernel?
>
>> @@ -271,6 +277,10 @@ static int phy_meson8b_usb2_probe(struct
>> platform_device *pdev)
>>                  return -EINVAL;
>>          }
>>
>> +       priv->reset = of_reset_control_get_shared(pdev->dev.of_node,
>> "phy-reset");
> this causes a memory-leak upon driver removal
> also a few lines above we are already getting the reset line, so why
> is this needed?
>
>
> Best regards,
> Martin
>