mainline/master boot bisection: v4.15-rc3 on peach-pi #3228-staging

[Krzysztof Kozlowski]

On Tue, Dec 12, 2017 at 9:47 AM, Marek Szyprowski
<m.szyprowski at samsung.com> wrote:
> Hi Javier,
>
> On 2017-12-12 09:00, Javier Martinez Canillas wrote:
>>
>> On Tue, Dec 12, 2017 at 8:54 AM, Marek Szyprowski
>> <m.szyprowski at samsung.com> wrote:

(...)

>>> This warning has been added intentionally, see following discussions:
>>> https://patchwork.kernel.org/patch/10034919/
>>> https://patchwork.kernel.org/patch/10070475/
>>>
>>> This means that your test apps should be updated or you should enable
>>> Exynos
>>> IOMMU support in your config. Maybe it is a good time to finally enable
>>> it
>>> in exynos_defconfig.
>>>
>> Has the issue that the boot-loader keeps the display controller
>> enabled and scanning pages on the Exynos Chromebooks resolved?
>>
>> I think that's that preventing to enable it by default in
>> exynos_defconfig since it caused boot failures when enabled on these
>> machines. I don't follow exynos development too closely nowadays so
>> maybe there's a fix in place now.
>
>
> Not directly. I still didn't find time to properly add support for
> devices, which were left in-working state (with active DMA
> transactions) by bootloader, but due to some other changes in the
> order of operations during boot process, power domains are
> initialized very early and due to temporary lack of devices (which
> are not yet added to the system), are turned off. This practically
> stops FIMD for scanning framebuffer and "solves" this issue.
>
> I've checked now and Exynos Snow Chromebook boots fine with IOMMU
> support enabled, both with v4.15-rc3 and linux-next.

Then it looks like we could give EXYNOS_IOMMU a try. At least only on
exynos_defconfig which would leave multi_v7 as a platform to compare.

Best regards,
Krzysztof