From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 2/2] usb: host: pci_quirks: Force hard reset of Renesas uPD72020x USB controller To: Marc Zyngier , Bjorn Helgaas , Greg Kroah-Hartman References: <20170710155230.8622-1-marc.zyngier@arm.com> <20170710155230.8622-3-marc.zyngier@arm.com> Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Ard Biesheuvel From: Mathias Nyman Message-ID: <596CA772.2010603@intel.com> Date: Mon, 17 Jul 2017 15:02:58 +0300 MIME-Version: 1.0 In-Reply-To: <20170710155230.8622-3-marc.zyngier@arm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: On 10.07.2017 18:52, Marc Zyngier wrote: > The Renesas uPD72020x XHCI controller seems to suffer from a > really annoying bug, where it may retain some of its DMA programming > across a XHCI reset, and despite the driver correctly programming new > DMA addresses. This is visible if the device has been using 64bit DMA > addresses, and is then switched to using 32bit DMA addresses. The top > 32bits of the address (now zero) are ignored are replaced by the 32bit > from the *previous* programming. Sticking with 64bit DMA always works, > but doesn't seem very appropriate. > > A PCI reset of the device restores the normal functionnality, which > is done at probe time. Unfortunately, this has to be done before > any quirk has been discovered, hence the intrusive nature of the fix. > > Signed-off-by: Marc Zyngier > --- > drivers/usb/host/pci-quirks.c | 20 ++++++++++++++++++++ > drivers/usb/host/pci-quirks.h | 1 + > drivers/usb/host/xhci-pci.c | 7 +++++++ > 3 files changed, 28 insertions(+) > Acked-by: Mathias Nyman