From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [BACKPORT 4.14.y 04/18] usb: dwc3: Allow disabling of metastability workaround Date: Tue, 10 Sep 2019 15:36:01 +0100 Message-ID: <20190910143601.GD3362@kroah.com> References: <20190905161759.28036-1-mathieu.poirier@linaro.org> <20190905161759.28036-5-mathieu.poirier@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190905161759.28036-5-mathieu.poirier@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: Mathieu Poirier Cc: stable@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, linux-i2c@vger.kernel.org, linux-pci@vger.kernel.org, linux-mtd@lists.infradead.org List-Id: linux-i2c@vger.kernel.org On Thu, Sep 05, 2019 at 10:17:45AM -0600, Mathieu Poirier wrote: > From: Roger Quadros > > commit 42bf02ec6e420e541af9a47437d0bdf961ca2972 upstream > > Some platforms (e.g. TI's DRA7 USB2 instance) have more trouble > with the metastability workaround as it supports only > a High-Speed PHY and the PHY can enter into an Erratic state [1] > when the controller is set in SuperSpeed mode as part of > the metastability workaround. > > This causes upto 2 seconds delay in enumeration on DRA7's USB2 > instance in gadget mode. > > If these platforms can be better off without the workaround, > provide a device tree property to suggest that so the workaround > is avoided. > > [1] Device mode enumeration trace showing PHY Erratic Error. > irq/90-dwc3-969 [000] d... 52.323145: dwc3_event: event (00000901): Erratic Error [U0] > irq/90-dwc3-969 [000] d... 52.560646: dwc3_event: event (00000901): Erratic Error [U0] > irq/90-dwc3-969 [000] d... 52.798144: dwc3_event: event (00000901): Erratic Error [U0] Does the DT also need to get updated with this new id for this? Is that a separate patch somewhere? thanks, greg k-h