From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH 3/4] usb: dwc2: assert phy reset when waking up in rk3288 platform Date: Sun, 21 Aug 2016 00:30:27 +0300 Message-ID: <4c931176-a09a-546c-d2b6-ea74028c78a2@cogentembedded.com> References: <7ca3b54d-e9d8-a137-79b6-d24f0b7065c7@synopsys.com> <1471725140-3833-1-git-send-email-ayaka@soulik.info> <1471725140-3833-4-git-send-email-ayaka@soulik.info> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1471725140-3833-4-git-send-email-ayaka@soulik.info> Sender: linux-kernel-owner@vger.kernel.org To: Randy Li , linux-usb@vger.kernel.org Cc: johnyoun@synopsys.com, gregkh@linuxfoundation.org, robh+dt@kernel.org, mark.rutland@arm.com, devicetree@vger.kernel.org, eddie.cai@rock-chips.com, randy.li@rock-chips.com, kishon@ti.com, linux-kernel@vger.kernel.org, heiko@sntech.de List-Id: devicetree@vger.kernel.org Hello. On 08/20/2016 11:32 PM, Randy Li wrote: > On the rk3288 USB host-only port (the one that's not the OTG-enabled > port) the PHY can get into a bad state when a wakeup is asserted (not > just a wakeup from full system suspend but also a wakeup from > autosuspend). > > We can get the PHY out of its bad state by asserting its "port reset", > but unfortunately that seems to assert a reset onto the USB bus so it > could confuse things if we don't actually deenumerate / reenumerate the > device. > > We can also get the PHY out of its bad state by fully resetting it using > the reset from the CRU (clock reset unit) in chip, which does a more full > reset. The CRU-based reset appears to actually cause devices on the bus > to be removed and reinserted, which fixes the problem (albeit in a hacky > way). > > It's unfortunate that we need to do a full re-enumeration of devices at > wakeup time, but this is better than alternative of letting the bus get > wedged. > > The original patches came from Doug Anderson . > > Signed-off-by: Randy Li > --- > drivers/usb/dwc2/core_intr.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c > index d85c5c9..c31c3fe 100644 > --- a/drivers/usb/dwc2/core_intr.c > +++ b/drivers/usb/dwc2/core_intr.c [...] > @@ -379,6 +380,14 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg) > /* Restart the Phy Clock */ > pcgcctl &= ~PCGCTL_STOPPCLK; > dwc2_writel(pcgcctl, hsotg->regs + PCGCTL); > + > + /* It is a quirk in Rockchip RK3288, causing by > + * a hardware bug. This will propagate out and > + * eventually we'll re-enumerate the device. > + * Not great but the best we can do */ The preferred multi-line comment style is this: /* * bla * bla */ Yours is close. :-) [...] MBR, Sergei