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Subject: Re: [RFC PATCH] USB: PCI: set 32bit DMA mask for PCI based USB
 controllers
From:   Hanjun Guo <guohanjun@huawei.com>
To:     John Garry <john.garry@huawei.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Robin Murphy <robin.murphy@arm.com>,
        "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Christoph Hellwig <hch@lst.de>
CC:     <linux-usb@vger.kernel.org>, <linux-acpi@vger.kernel.org>,
        <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linuxarm@huawei.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        <anthony.jebson@huawei.com>, Hanjun Guo <hanjun.guo@linaro.org>
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 <ce031291-3050-3817-0ed9-9d83dad0cc55@huawei.com>
Message-ID: <e47d89e3-9bb0-95b0-db63-717594b1692b@huawei.com>
Date:   Fri, 1 Feb 2019 17:13:52 +0800
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On 2019/2/1 13:55, Hanjun Guo wrote:
> Hi John,
> 
> On 2019/1/31 17:54, John Garry wrote:
>> On 30/01/2019 07:01, Hanjun Guo wrote:
>>> From: Hanjun Guo <hanjun.guo@linaro.org>
> [...]
>>>
>>> ?drivers/usb/core/hcd-pci.c | 4 ++++
>>> ?1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
>>> index 0343246..a9c33e6 100644
>>> --- a/drivers/usb/core/hcd-pci.c
>>> +++ b/drivers/usb/core/hcd-pci.c
>>> @@ -188,6 +188,10 @@ int usb_hcd_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
>>> ???? if (pci_enable_device(dev) < 0)
>>> ???????? return -ENODEV;
>>>
>>> +??? retval = dma_coerce_mask_and_coherent(&dev->dev, DMA_BIT_MASK(32));
>>> +??? if (retval)
>>> +??????? return retval;
>>
>> Hi Hanjun,
>>
>> You're missing tidy-up upon failure.
> 
> Good catch, needs to disable pci for failure, I will send
> a updated version to address the comments from you and Christoph.

There is a _DMA method which was introduced in ACPI 6.2 to cover
this, I will try that solution then report back.

Thanks
Hanjun