Hi Martin

Thanks for your review comments.

On Sat, 19 Jun 2021 at 01:36, Martin Blumenstingl
[off-list ref] wrote:

Hi Anand,

On Fri, Jun 18, 2021 at 5:33 PM Anand Moon [off-list ref] wrote:
[...]

quoted

quoted

For shared resets (like the one we have here) reset_control_reset will
only trigger the reset line once until all drivers using that reset
line are unloaded.
So effectively this new phy_ops.reset callback will be a no-op.

I know his register is shared between two USB IPs,
but I have not observed any issues.

have you checked at which point we're then actually triggering the reset?
I assume that you will find that the reset is only triggered for the
very first power_on/init call - which makes this patch effectively a
no-op (yes, we're calling reset_control_reset then, but that doesn't
mean that a reset is triggered on hardware level - see
drivers/reset/core.c at around line 346).

Ok Thanks for the inputs. got your point.

I was also looking into Amlogic source code for reset. (aml_cbus_update_bits)
[0] https://github.com/khadas/linux/blob/khadas-vims-4.9.y/drivers/amlogic/usb/phy/phy-aml-new-usb.c
is there some feature to iomap the USB with cbus?

[...]

quoted

quoted

quoted

-       priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+       priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, "phy");

I think this breaks compatibility with existing .dtbs and our
dt-bindings (as we're not documenting a "reset-names" property).
What is the goal of this one?

OK, If we pass NULL over here there is the possibility
USB phy will not get registered.

I don't understand why - with NULL everything is working fine for me.
Also no matter which name you give to the reset line (in reset-names),
it will be the same reset line in all cases. If it's the same reset
line before and after: why is this needed?

I need to investigate this reset feature. With my setup with current changes
after I update the below.
-       priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, "phy");
+       priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
        if (PTR_ERR(priv->reset) == -EPROBE_DEFER)
                return PTR_ERR(priv->reset);

Reset will break the USB initialization, see below output.

[    1.265403] dwc2 c9040000.usb: mapped PA c9040000 to VA (ptrval)
[    1.265540] dwc2 c9040000.usb: Looking up vusb_d-supply from device tree
[    1.265554] dwc2 c9040000.usb: Looking up vusb_d-supply property in
node /soc/usb@c9040000 failed
[    1.265585] dwc2 c9040000.usb: supply vusb_d not found, using dummy regulator
[    1.265717] dwc2 c9040000.usb: Looking up vusb_a-supply from device tree
[    1.265730] dwc2 c9040000.usb: Looking up vusb_a-supply property in
node /soc/usb@c9040000 failed
[    1.265752] dwc2 c9040000.usb: supply vusb_a not found, using dummy regulator
[    1.265812] dwc2 c9040000.usb: registering common handler for irq35
[    1.265867] dwc2 c9040000.usb: Looking up vbus-supply from device tree
[    1.265880] dwc2 c9040000.usb: Looking up vbus-supply property in
node /soc/usb@c9040000 failed
[    1.267066] dwc2 c9040000.usb: Core Release: 3.10a (snpsid=4f54310a)
[    1.270983] dwc2 c9040000.usb: dwc2_core_reset: HANG! Soft Reset
timeout GRSTCTL_CSFTRST
[    1.271319] dwc2: probe of c9040000.usb failed with error -16
[    1.273296] dwc2 c90c0000.usb: mapped PA c90c0000 to VA (ptrval)
[    1.273426] dwc2 c90c0000.usb: Looking up vusb_d-supply from device tree
[    1.273440] dwc2 c90c0000.usb: Looking up vusb_d-supply property in
node /soc/usb@c90c0000 failed
[    1.273471] dwc2 c90c0000.usb: supply vusb_d not found, using dummy regulator
[    1.273607] dwc2 c90c0000.usb: Looking up vusb_a-supply from device tree
[    1.273621] dwc2 c90c0000.usb: Looking up vusb_a-supply property in
node /soc/usb@c90c0000 failed
[    1.273641] dwc2 c90c0000.usb: supply vusb_a not found, using dummy regulator
[    1.273700] dwc2 c90c0000.usb: registering common handler for irq36
[    1.273750] dwc2 c90c0000.usb: Looking up vbus-supply from device tree
[    1.273762] dwc2 c90c0000.usb: Looking up vbus-supply property in
node /soc/usb@c90c0000 failed
[    1.274966] dwc2 c90c0000.usb: Core Release: 3.10a (snpsid=4f54310a)
[    1.278888] dwc2 c90c0000.usb: dwc2_core_reset: HANG! Soft Reset
timeout GRSTCTL_CSFTRST
[    1.279224] dwc2: probe of c90c0000.usb failed with error -16

Best regards,
Martin

Thanks
-Anand

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