Workaround for dw_dmac causing random hang when booting

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apport-collect 1501580

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This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-vivid' to 'verification-done-vivid'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

Test:
1. Remove `blacklist dw_dmac` workaround
2. Install proposed kernel
3. Test if system hangs -> pass
4. Check if the message "HP X360 detected, skip probing" appears -> yes

Since in the patch it compares the product name in DMI string to decide if to skip the dw_dmac probing, so no side-effect is expected.

This bug was fixed in the package linux - 3.19.0-32.37

---------------
linux (3.19.0-32.37) vivid; urgency=low

  [ Luis Henriques ]

  * Release Tracking Bug
    - LP: #1508381

  [ Joseph Salisbury ]

  * SAUCE: storvsc: use small sg_tablesize on x86
    - LP: #1495983

  [ Phidias Chiang ]

  * SAUCE: dma: dw_dmac: Workaround for stop probing on HP X360 laptop v2
    - LP: #1501580

  [ Tim Gardner ]

  * [Config] Add MMC modules sufficient for net booting
    - LP: #1502772

  [ Upstream Kernel Changes ]

  * USB: whiteheat: fix potential null-deref at probe
    - LP: #1478826
    - CVE-2015-5257
  * dcache: Handle escaped paths in prepend_path
    - LP: #1441108
    - CVE-2015-2925
  * vfs: Test for and handle paths that are unreachable from their mnt_root
    - LP: #1441108
    - CVE-2015-2925
  * hv_netvsc: Add support to set MTU reservation from guest side
    - LP: #1494431
  * hv_netvsc: Add close of RNDIS filter into change mtu call
    - LP: #1494431
  * powerpc/eeh: Fix missed PE#0 on P7IOC
    - LP: #1502982
  * powerpc/powernv: display reason for Malfunction Alert HMI.
    - LP: #1482343
  * powerpc/powernv: Pull all HMI events before panic.
    - LP: #1482343
  * powerpc/powernv: Invoke opal_cec_reboot2() on unrecoverable machine
    check errors.
    - LP: #1482343
  * powerpc/powernv: Invoke opal_cec_reboot2() on unrecoverable HMI.
    - LP: #1482343
  * powerpc/eeh: Fix PE#0 check in eeh_add_to_parent_pe()
    - LP: #1502982
  * HID: i2c-hid: The interrupt should be level sensitive v2
    - LP: #1501187
  * HID: i2c-hid: Add support for ACPI GPIO interrupts v2
    - LP: #1501187

 -- Luis Henriques <email address hidden> Wed, 21 Oct 2015 10:30:13 +0100

This bug also appears on Acer Aspire E15 Laptops (E5-511-P7AT) and (E5-511-P01P) on 14.04.3 Trusty with kernel 3.19.0-28.

If dw_dmac and dw_dmac_core are not blacklisted, everytime on Shut Down or Reboot comes a black screen and the fan starts spinning like crazy every +-20 seconds, but the machine doesn't shut down or reboot.

I hope this issue will be fixed for the next LTS 16.04 ?

Phidias - Do you think this patch should be applied to Wily and Xenial ?

At the moment I'll say no.

This issue doesn't happen anymore after firmware update on HP X360. I've asked FE in Taipei to help downgrading the firmware last week, so I can verify some patches for dw_dmac, and hopefully can also fix the issue in #6

If there are fixes for this issue, I'll open another bug to send SRU, and revert this workaround.

Read comment #8 at https://bugzilla.kernel.org/show_bug.cgi?id=101271