From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72547C5CFE7 for ; Mon, 9 Jul 2018 22:04:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DA6B2086B for ; Mon, 9 Jul 2018 22:04:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2DA6B2086B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933025AbeGIWEX (ORCPT ); Mon, 9 Jul 2018 18:04:23 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:40504 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751038AbeGIWEV (ORCPT ); Mon, 9 Jul 2018 18:04:21 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id 44C2F277B9D Message-ID: <536642654ca55f08877497c86a5cb106d5458384.camel@collabora.com> Subject: Re: [PATCH] usb: dwc3: of-simple: reset host controller at suspend/resume From: Ezequiel Garcia To: Enric Balletbo i Serra , linux-kernel@vger.kernel.org Cc: briannorris@chromium.org, kernel@collabora.com, heiko@sntech.de, Greg Kroah-Hartman , linux-usb@vger.kernel.org, Felipe Balbi , "mailto:devicetree"@vger.kernel.org Date: Mon, 09 Jul 2018 19:04:12 -0300 In-Reply-To: <20180709150844.32505-1-enric.balletbo@collabora.com> References: <20180709150844.32505-1-enric.balletbo@collabora.com> Organization: Collabora Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.2-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (Cc devicetree folks) Hi Enric, Thanks for the patch. On Mon, 2018-07-09 at 17:08 +0200, Enric Balletbo i Serra wrote: > If we power off the SoC logic rail in S3, we can find that the Type-C > PHY can't initialize correctly after system resume. We need to toggle > the USB3-OTG reset before trying to initialize the PHY, or else it > times out. > > phy phy-ff800000.phy.9: phy poweron failed --> -110 > dwc3 fe900000.dwc3: failed to initialize core > dwc3: probe of fe900000.dwc3 failed with error -110 > > Note that the RK3399 TRM suggests that we should keep the whole usb3 > controller in reset for the duration of the Type-C PHY > initialization. > However, it's hard to assert the reset in the current framework of > reset. We're still skeptical about that, and we haven't yet found a > case where this seems to have mattered. This approach is much easier, > it > simply holds the USB3-OTG reset while device is supended. > > The dwc3 core is going to reinitialize the controller at > suspend/resume > anyway (including a "soft reset"), so it should be safe to do this. > > Signed-off-by: Enric Balletbo i Serra > --- > Dear all, > > Now that the usb3-phy otg port support for rk3399 has been merged [1] > we > found that suspend/resume is broken. The problem is well known for > ChromeOS kernels, they solved it in a similar way adding a reset > pulse on > resume in the specific usb glue layer (dwc3-rockchip). In mainline, > though, we use the dwc3-of-simple glue layer instead of a specific > layer > for rockchip. The patch is based on the Brian Norris work but > slightly > different, it holds the reset while device is suspended. It was > tested > on a Samsung Chromebook Plus with usbc docking station attached by > doing > different suspend/resume cycles and checking no usb devices has been > lost. > > I am not sure this is the better way to solve this but I did not find > any other way, and, as I am not sure this can be generic, the reset > is only > done on rockchip platforms. > I don't really understand why there are per-platform hacks in glue drivers, instead of having per-platform glue drivers, or some other pluggable hooks. > Best regards, > Enric > > [1] bfdca1736ea76345071bbc5607d18928e54909ac ('arm64: dts: rockchip: > add > usb3-phy otg-port support for rk3399') > > drivers/usb/dwc3/dwc3-of-simple.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/drivers/usb/dwc3/dwc3-of-simple.c > b/drivers/usb/dwc3/dwc3-of-simple.c > index dbeff5e6ad14..1d1ece99ed94 100644 > --- a/drivers/usb/dwc3/dwc3-of-simple.c > +++ b/drivers/usb/dwc3/dwc3-of-simple.c > @@ -201,9 +201,30 @@ static int dwc3_of_simple_runtime_resume(struct > device *dev) > > return 0; > } > + > +static int dwc3_of_simple_suspend(struct device *dev) > +{ > + struct dwc3_of_simple *simple = dev_get_drvdata(dev); > + > + if (of_device_is_compatible(dev->of_node, "rockchip,rk3399- > dwc3")) > Instead of calling of_device_is_compatible in each suspend/resume, which seems quite expensive, how about having a per-device boolean 'needs_reset' or something like that? Or maybe just have a boolean devicetree property for this? Regards, Eze