From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:44632)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <lvivier@redhat.com>) id 1bon3B-00026z-69
	for qemu-devel@nongnu.org; Tue, 27 Sep 2016 03:43:38 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <lvivier@redhat.com>) id 1bon36-00048F-4Z
	for qemu-devel@nongnu.org; Tue, 27 Sep 2016 03:43:37 -0400
References: <1474899049-12506-1-git-send-email-lvivier@redhat.com>
	<1474899049-12506-5-git-send-email-lvivier@redhat.com>
	<20160927035313.GC30322@umbus.fritz.box>
From: Laurent Vivier <lvivier@redhat.com>
Message-ID: <e3ba35a8-e300-4460-33de-6ee5a9c42689@redhat.com>
Date: Tue, 27 Sep 2016 09:43:27 +0200
MIME-Version: 1.0
In-Reply-To: <20160927035313.GC30322@umbus.fritz.box>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 4/4] tests: enable
 ohci/uhci/xhci tests on PPC64
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-devel@nongnu.org, thuth@redhat.com, Greg Kurz <groug@kaod.org>, qemu-ppc@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>, dgibson@redhat.com



On 27/09/2016 05:53, David Gibson wrote:
> On Mon, Sep 26, 2016 at 04:10:49PM +0200, Laurent Vivier wrote:

>>  void qusb_pci_init_one(QPCIBus *pcibus, struct qhc *hc, uint32_t devfn, int bar)
>>  {
>>      hc->dev = qpci_device_find(pcibus, devfn);
>> @@ -31,6 +38,13 @@ void uhci_port_test(struct qhc *hc, int port, uint16_t expect)
>>      uint16_t value = qpci_io_readw(hc->dev, addr);
>>      uint16_t mask = ~(UHCI_PORT_WRITE_CLEAR | UHCI_PORT_RSVD1);
>>  
>> +    if (qtest_big_endian() && host_big_endian) {
>> +        /* little endian device on big endian guest
>> +         * must be swapped on big endian host
>> +         */
>> +        value = bswap16(value);
>> +    }
>> +
> 
> Hm.. should the qpci_io_*() helpers handle the endian conversion?

I'm really wondering how to manage correctly this case (I've the same
kind of issue with virtio).

The protocol between guest and test program reads/writes data using the
guest CPU endianess, so it works in the overall case. But in this case,
hcd-uhci is a little-endian device (.endianness = DEVICE_LITTLE_ENDIAN)
on a big endian machine, so I think in the linux driver we should have a
"le16_to_cpu()". But in our case we can't use "le16_to_cpu()" because
endianess of the host cpu is not the same has the one of the guest CPU.
Perhaps I should add a "target_le16_to_cpu()"?

Thanks,
Laurent