Comment 8 for bug 1738334

It is good to update to "Fred" (Xin Wei) off-line and thank you very much
for it.

On Tue, Jan 23, 2018 at 8:46 AM, Daniel Axtens <email address hidden>

> I have talked to the kernel team about this and updated Fred off-line.
> --
> You received this bug notification because you are subscribed to the bug
> report.
> Title:
> hisilicon hibmc regression due to ea642c3216cb ("drm/ttm: add
> io_mem_pfn callback")
> Status in linux package in Ubuntu:
> Confirmed
> Bug description:
> [SRU Justification]
> [Impact]
> On Artful kernels, X fails to start and a kernel splat is printed.
> This is cbecause ea642c3216cb ("drm/ttm: add io_mem_pfn callback") is
> incomplete: the hisilicon hibmc driver does not contain the callback
> and so the kernel tries to execute code at NULL.
> [Fix]
> There is a discussion and potential fix at
> The fix hasn't landed yet and it looks like they're going to re-engineer
> the entire section instead.
> Rather than wait for that and deal with the massive regression
> potential, the fix I have picked to submit is very very minimal and
> touches only hibmc.
> [Regression Potential]
> Minimal - fix only touches hibmc driver. Tested on D05 board.
> [Testcase]
> Install patched kernel, try to start X. If it succeeds, the fix works.
> If there's a kernel splat, the fix does not work.
> [Notes]
> HiSilicon would really like this fix in Artful in such time so that when
> the next 16.04 point release ships in February, the HWE kernel will work
> with Xorg.
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Zhanglei Mao
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Canonical Group Ltd.
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