From: khilman@baylibre•com (Kevin Hilman)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB
Date: Thu, 08 Sep 2016 13:42:22 -0700 [thread overview]
Message-ID: <m2eg4ui0nl.fsf@baylibre.com> (raw)
In-Reply-To: <e3b1f611-d6f6-c98b-a53b-98e94ef5bd96@codethink.co.uk> (Ben Dooks's message of "Thu, 8 Sep 2016 21:20:12 +0100")
Ben Dooks <ben.dooks@codethink•co.uk> writes:
> On 08/09/16 20:52, Martin Blumenstingl wrote:
>> On Thu, Sep 8, 2016 at 9:35 PM, Kevin Hilman <khilman@baylibre•com> wrote:
>>>> + phy = devm_phy_create(&pdev->dev, NULL, &phy_meson_usb2_ops);
>>>> + if (IS_ERR(phy)) {
>>>> + dev_err(&pdev->dev, "failed to create PHY\n");
>>>> + return PTR_ERR(phy);
>>>> + }
>>>> +
>>>> + if (usb_reset_refcnt++ == 0) {
>>>> + ret = device_reset(&pdev->dev);
>>>> + if (ret) {
>>>> + dev_err(&phy->dev, "Failed to reset USB PHY\n");
>>>> + return ret;
>>>> + }
>>>> + }
>>>
>>> The ref count + reset here looks like something that could/should be
>>> handled in a runtime PM callback.
>> Unfortunately that doesn't work (as Jerome found out) because both
>> PHYs are sharing the same reset line.
>> So if the second PHY would call device_reset then it would also reset
>> the first PHY!
>>
>> There's a comment above the declaration of usb_reset_refcnt which
>> tries to explain this:
>> "The PHYs are sharing a common reset line -> we are only allowed to
>> reset once for all PHYs."
>> Maybe I should move this comment to the "if (usb_reset_refcnt++ == 0)
>> {" line to make it easier to see?
>>
>
> pm-runtime has refcounting in it. When one of the nodes turns on,
> the pm-runtime will call your driver to say there is a user when
> this first use turns up.
>
> If all the sub-phys turn off and drop their refcount then the driver
> is called to say there are no more users and you can go to sleep.
After a chat w/Martin on IRC, It turns out runtime PM wont help here.
The reason is because there are physically two PHY devices[1]. Those 2
devices will be treated independely by runtime PM, and have separate
use-counting, which means doing what I proposed would cause a reset to
happen when either device was probed.
So, I think it's OK as it is.
Kevin
[1] from the DT patch:
diff --git a/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi b/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
index 2e8a3d9..02dfc54 100644
--- a/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi
@@ -151,6 +151,34 @@
#size-cells = <2>;
ranges;
+ usb-phys at c0000000 {
+ compatible = "simple-bus";
+ reg = <0x0 0xc0000000 0x0 0x40>;
+ #address-cells = <2>;
+ #size-cells = <2>;
+ ranges = <0x0 0x0 0x0 0xc0000000 0x0 0x40>;
+
+ usb0_phy: usb_phy at 0 {
+ compatible = "amlogic,meson-gxbb-usb2-phy";
+ #phy-cells = <0>;
+ reg = <0x0 0x0 0x0 0x20>;
+ resets = <&reset 34>;
+ clocks = <&clkc CLKID_USB &clkc CLKID_USB0>;
+ clock-names = "usb_general", "usb";
+ status = "disabled";
+ };
+
+ usb1_phy: usb_phy at 20 {
+ compatible = "amlogic,meson-gxbb-usb2-phy";
+ #phy-cells = <0>;
+ reg = <0x0 0x20 0x0 0x20>;
+ resets = <&reset 34>;
+ clocks = <&clkc CLKID_USB &clkc CLKID_USB1>;
+ clock-names = "usb_general", "usb";
+ status = "disabled";
+ };
+ };
+
next prev parent reply other threads:[~2016-09-08 20:42 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-04 21:31 [PATCH 0/7] usb/phy: Add Amlogic Meson8b and GXBB USB support Martin Blumenstingl
2016-09-04 21:31 ` [PATCH 1/7] clk: gxbb: expose USB clocks Martin Blumenstingl
2016-09-07 0:33 ` Stephen Boyd
2016-09-07 21:32 ` Martin Blumenstingl
2016-09-07 22:14 ` Stephen Boyd
2016-09-08 2:24 ` Kevin Hilman
2016-09-07 21:28 ` Stephen Boyd
2016-09-08 19:24 ` Kevin Hilman
2016-09-04 21:31 ` [PATCH 2/7] usb: dwc2: add support for Meson8b and GXBB SoCs Martin Blumenstingl
2016-09-07 21:04 ` John Youn
2016-09-04 21:31 ` [PATCH 3/7] Documentation: dt-bindings: Add documentation for the Meson USB2 PHYs Martin Blumenstingl
2016-09-04 21:31 ` [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB Martin Blumenstingl
2016-09-08 19:35 ` Kevin Hilman
2016-09-08 19:40 ` Ben Dooks
2016-09-08 19:52 ` Martin Blumenstingl
2016-09-08 20:20 ` Ben Dooks
2016-09-08 20:42 ` Kevin Hilman [this message]
2016-09-08 20:53 ` Ben Dooks
2016-09-08 21:48 ` Martin Blumenstingl
2016-09-09 15:33 ` Kevin Hilman
2016-09-09 16:14 ` Martin Blumenstingl
2016-09-09 17:04 ` Kevin Hilman
2016-09-09 17:21 ` Ben Dooks
2016-09-09 20:37 ` Martin Blumenstingl
2016-09-16 8:19 ` Kishon Vijay Abraham I
2016-09-16 13:47 ` Arnd Bergmann
2016-09-18 19:56 ` Martin Blumenstingl
2016-09-19 4:59 ` Kishon Vijay Abraham I
2016-09-19 7:37 ` Arnd Bergmann
2016-09-09 20:36 ` Martin Blumenstingl
2016-09-11 13:44 ` Martin Blumenstingl
2016-09-12 17:32 ` Kevin Hilman
2016-09-13 15:28 ` Philipp Zabel
2016-09-13 18:38 ` Martin Blumenstingl
2016-09-14 0:59 ` Kevin Hilman
2016-09-14 8:36 ` Philipp Zabel
2016-09-14 8:37 ` Philipp Zabel
2016-09-14 21:09 ` Martin Blumenstingl
2016-09-14 8:37 ` Philipp Zabel
2016-09-14 21:23 ` Martin Blumenstingl
2016-09-15 10:30 ` Philipp Zabel
2016-09-04 21:31 ` [PATCH 5/7] ARM64: meson-gxbb: add USB Nodes Martin Blumenstingl
2016-09-05 0:23 ` Andreas Färber
2016-09-04 21:31 ` [PATCH 6/7] ARM64: meson-gxbb-p20x: Enable " Martin Blumenstingl
2016-09-04 21:31 ` [PATCH 7/7] ARM64: meson-gxbb-vega-s95: " Martin Blumenstingl
2016-09-11 13:41 ` [PATCH v2 0/6] usb/phy: Add Amlogic Meson8b and GXBB USB support Martin Blumenstingl
2016-09-11 13:41 ` [PATCH v2 1/6] usb: dwc2: add support for Meson8b and GXBB SoCs Martin Blumenstingl
2016-09-14 16:11 ` Kevin Hilman
2016-09-14 18:12 ` John Youn
2016-09-14 18:17 ` Kevin Hilman
2016-09-14 18:26 ` John Youn
2016-09-14 18:36 ` Kevin Hilman
2016-09-20 14:27 ` Rob Herring
2016-09-11 13:41 ` [PATCH v2 2/6] Documentation: dt-bindings: Add documentation for the Meson USB2 PHYs Martin Blumenstingl
2016-09-20 14:29 ` Rob Herring
2016-09-21 18:38 ` Kevin Hilman
2016-09-11 13:41 ` [PATCH v2 3/6] phy: meson: add USB2 PHY support for Meson8b and GXBB Martin Blumenstingl
2016-09-14 16:06 ` Kevin Hilman
2016-09-17 4:17 ` Kishon Vijay Abraham I
2016-09-19 16:42 ` Kevin Hilman
2016-09-20 5:01 ` Kishon Vijay Abraham I
2016-09-14 21:30 ` Martin Blumenstingl
2016-09-11 13:41 ` [PATCH v2 4/6] ARM64: meson-gxbb: add USB Nodes Martin Blumenstingl
2016-09-15 22:10 ` Kevin Hilman
2016-09-11 13:41 ` [PATCH v2 5/6] ARM64: meson-gxbb-p20x: Enable " Martin Blumenstingl
2016-09-14 18:05 ` Kevin Hilman
2016-09-15 22:09 ` Kevin Hilman
2016-09-11 13:41 ` [PATCH v2 6/6] ARM64: meson-gxbb-vega-s95: " Martin Blumenstingl
2016-09-15 22:10 ` Kevin Hilman
2016-10-01 12:18 ` [PATCH v3 0/3] usb/phy: Add Amlogic Meson8b and GXBB USB support Martin Blumenstingl
2016-10-01 12:18 ` [PATCH v3 1/3] Documentation: dt-bindings: update the meson-usb2-phy example Martin Blumenstingl
2016-10-09 1:28 ` Rob Herring
2016-10-01 12:18 ` [PATCH v3 2/3] Documentation: dt-bindings: rename meson-usb2-phy to meson8b-usb2-phy Martin Blumenstingl
2016-10-09 1:28 ` Rob Herring
2016-10-01 12:19 ` [PATCH v3 3/3] phy: meson: add USB2 PHY support for Meson8b and GXBB Martin Blumenstingl
2016-10-13 20:27 ` [PATCH v3 0/3] usb/phy: Add Amlogic Meson8b and GXBB USB support Martin Blumenstingl
2016-10-19 10:52 ` Kishon Vijay Abraham I
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