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Mon, 11 Jun 2018 15:45:23 +0000 From: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk> To: Mathias Kresin <dev@kresin.me> CC: "openwrt-devel@lists.openwrt.org" <openwrt-devel@lists.openwrt.org> Subject: Re: [PATCH] ramips: mir3g: reduce usb power flapping at boot Thread-Topic: [PATCH] ramips: mir3g: reduce usb power flapping at boot Thread-Index: AQHT/1kJdqFXOpTsRUyXxzbRiS0jf6RbKi8AgAANiAA= Date: Mon, 11 Jun 2018 15:45:23 +0000 Message-ID: <0A89B56F-8B28-4FAB-8C60-891D0D70D81D@darbyshire-bryant.me.uk> References: <20180608184534.43084-1-ldir@darbyshire-bryant.me.uk> <dae711da-a7dc-a157-c698-ed2840f1600d@kresin.me> In-Reply-To: <dae711da-a7dc-a157-c698-ed2840f1600d@kresin.me> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [2a02:c7f:1231:2000::dc83] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; VI1PR07MB1053; 7:Q9BA/yPEGJ7VsnCxRzxIrJeZq2hyEpBK5sVORVO2d+zF4TZkcWdWo1ukyAFtv08OOxJfzuePmmIGjF6ks1fGmMqHvleof3+6VWtlGjF1GgGwvIMv7CP4Xg8iXMZfdfWGkNUZa0CldNYdb5KrxDzjBXHtU2VawnSu6Zjx9+kjEofa0TijJND3sV6MiMY4cbFvc27bGXbn3px2fG1xQqniC4Rz6WI0mcpxN5l8gxP0+dV9PgMYlCqHbSjOM6cBsojt x-ms-exchange-antispam-srfa-diagnostics: SOS; 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charset="us-ascii" Content-ID: <9A03D515AE1818439BF45FA22F435F4F@eurprd07.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Office365-Filtering-Correlation-Id: 3ecfc51c-25b9-4343-807f-08d5cfb2586f X-OriginatorOrg: darbyshire-bryant.me.uk X-MS-Exchange-CrossTenant-Network-Message-Id: 3ecfc51c-25b9-4343-807f-08d5cfb2586f X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Jun 2018 15:45:23.5442 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 9151708b-c553-406f-8e56-694f435154a4 X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR07MB1053 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180611_084541_786587_BE693EC3 X-CRM114-Status: GOOD ( 12.70 ) X-Spam-Score: -0.1 (/) X-Spam-Report: SpamAssassin version 3.4.1 on bombadil.infradead.org summary: Content analysis details: (-0.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2a01:111:f400:fe1e:0:0:0:624 listed in] [list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain > On 11 Jun 2018, at 15:56, Mathias Kresin <dev@kresin.me> wrote: >=20 > 08.06.2018 20:45, Kevin Darbyshire-Bryant: >> Define USB port power as set on by bootloader (which it is) The power >> gets cycled at kernel boot, but by defining as 'regulator-boot-on' >> reduces the power off to power on at driver initial load & setup from >> around 5 seconds to around 2 seconds. >> Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk> >> --- >> target/linux/ramips/dts/MIR3G.dts | 1 + >> 1 file changed, 1 insertion(+) >> diff --git a/target/linux/ramips/dts/MIR3G.dts b/target/linux/ramips/dts= /MIR3G.dts >> index 44dfc1796c..1ca085e6c4 100644 >> --- a/target/linux/ramips/dts/MIR3G.dts >> +++ b/target/linux/ramips/dts/MIR3G.dts >> @@ -72,6 +72,7 @@ >> regulator-min-microvolt =3D <5000000>; >> regulator-max-microvolt =3D <5000000>; >> gpio =3D <&gpio0 12 GPIO_ACTIVE_HIGH>; >> + regulator-boot-on; >> enable-active-high; >> }; >=20 > NAK on this one. >=20 > Following our conversation on IRC, I had a look at the fixed regulator co= de to see what it really does. By default the regulator is disabled during = driver load[0]. The "regulator-boot-on" inverts the logic and enables the r= egulator while loading the fixed regulator driver. >=20 > In my opinion, enabling the fixed regulator unconditionally on boot contr= adicts your initial "switch to fixed regulator" patch. Without the "regulat= or-boot-on", the GPIO is pulled LOW (usb pwr disabled) on boot and it's the= usb driver which enables the usb pwr (pulls HIGH) =3D=3D controls the powe= r supply. This way the usb pwr stays/is off, if someone decides to not incl= ude or load the usb driver. >=20 > Mathias >=20 > [0] https://github.com/torvalds/linux/blob/master/drivers/regulator/fixed= .c#L159 I ack your nack. Absolutely fine reasoning. Cheers, Kevin D-B 012C ACB2 28C6 C53E 9775 9123 B3A2 389B 9DE2 334A ]