IEEE 1394 subsystem patches:

- make JMicron JMB38x controllers work with IOMMU-equipped systems
   - IP-over-1394: allow user-configured MTU of up to 4096 bytes
 -----BEGIN PGP SIGNATURE-----
 
 iQJOBAABCAA4FiEElVwAmOXEbvmhUkgUefNvslRdedAFAlp0aGYaHHN0ZWZhbnJA
 czVyNi5pbi1iZXJsaW4uZGUACgkQefNvslRdedDOHg/+NBs+6uv7SDZ2HXfQ6EQs
 ytoAaPMjrSWztHWrz3JM/Q1CECgwYJhq3pWqTCIho2CXE/PFJF0YvqSgg45buzW1
 sBOsJ6Sn5yIFTcHw9IDcTjI73lNLjEyBuft7KzHswCYbNbftOaebVE+19D24wOCb
 MspCcrqqQehmlHLrmhJmkv9n4kUEx7v/ZT5lXy4gXxO3/NvQ02Vq7AblbNX1/mcy
 Lf7ONqWi4cjY5sp49KuR0tZJZmclYodUnqkCSSRsLGtJSj/oacMufqk9/LU80Oc4
 0J9Xzf4kRGWxmdO7TqLRu4632oZeXjX/q57IsKJOcjIqPX/FDAWOdBadaEEVOSLy
 AOwpXQ3GOl9SC8HmSptTSzMedRoxszwZ7NdbLvkuydoPa2mpTyxHYhOf1gy6639g
 fa0iQ8LdzDIjI1R8bka9SWVmUlxaOFKbYMqhuWk+ugoG4QtZKpCdXs4MFOmSyWGX
 kAtanLXKijA1iVrr1Kn2Cf2MJlvjuYfG00X4dzKIsIEvZHgwXs2mYua5wNHy4eLe
 KrKC3WBGDkW81Zokk9FFvdsECvCc1W4z/bLIOWrGsMa3OLvA0jiZTVydQXMdZyHd
 GL2LtpwfCbuRUZkt/ScJ3ELyXDULviaBu/mlX4Ppc2c15JW/RSmwr3S/W/n0HL6j
 pe9TTDYRTnPpScJ2eI7NlYY=
 =FQUh
 -----END PGP SIGNATURE-----

Merge tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

Pull firewire updates from Stefan Richter

  - make JMicron JMB38x controllers work with IOMMU-equipped systems

  - IP-over-1394: allow user-configured MTU of up to 4096 bytes

* tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire-ohci: work around oversized DMA reads on JMicron controllers
  firewire: net: max MTU off by one

drivers/firewire/net.c

@@ -1480,9 +1480,14 @@ static int fwnet_probe(struct fw_unit *unit,
 		goto out;
 	dev->local_fifo = dev->handler.offset;
 
+	/*
+	 * default MTU: RFC 2734 cl. 4, RFC 3146 cl. 4
+	 * maximum MTU: RFC 2734 cl. 4.2, fragment encapsulation header's
+	 *              maximum possible datagram_size + 1 = 0xfff + 1
+	 */
 	net->mtu = 1500U;
 	net->min_mtu = ETH_MIN_MTU;
-	net->max_mtu = 0xfff;
+	net->max_mtu = 4096U;
 
 	/* Set our hardware address while we're at it */
 	ha = (union fwnet_hwaddr *)net->dev_addr;

drivers/firewire/ohci.c

@@ -1128,7 +1128,13 @@ static int context_add_buffer(struct context *ctx)
 		return -ENOMEM;
 
 	offset = (void *)&desc->buffer - (void *)desc;
-	desc->buffer_size = PAGE_SIZE - offset;
+	/*
+	 * Some controllers, like JMicron ones, always issue 0x20-byte DMA reads
+	 * for descriptors, even 0x10-byte ones. This can cause page faults when
+	 * an IOMMU is in use and the oversized read crosses a page boundary.
+	 * Work around this by always leaving at least 0x10 bytes of padding.
+	 */
+	desc->buffer_size = PAGE_SIZE - offset - 0x10;
 	desc->buffer_bus = bus_addr + offset;
 	desc->used = 0;