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

[Shuah Khan]

On 12/12/2017 01:47 AM, Marek Szyprowski 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:
>>> On 2017-12-12 00:25, Shuah Khan wrote:
>>>> On 12/11/2017 04:02 PM, Russell King - ARM Linux wrote:
>>>>> On Mon, Dec 11, 2017 at 10:58:29PM +0000, Russell King - ARM Linux wrote:
>>>>>> On Mon, Dec 11, 2017 at 11:54:48PM +0100, Javier Martinez Canillas
>>>>>> wrote:
>>>>>>> So I gave a quick look to this, and at the very least there's a bug in
>>>>>>> the Exynos5800 Peach Pi DTS caused by commit 1cb686c08d12 ("ARM: dts:
>>>>>>> exynos: Add status property to Exynos 542x Mixer nodes").
>>>>>>>
>>>>>>> I've posted a fix for that:
>>>>>>>
>>>>>>> https://patchwork.kernel.org/patch/10105921/
>>>>>>>
>>>>>>> I believe this could be also be the cause for the boot failure, since
>>>>>>> I see in the boot log that things start to go wrong after exynos-drm
>>>>>>> fails to bind the HDMI component:
>>>>>>>
>>>>>>> [ 2.916347] exynos-drm exynos-drm: failed to bind 14530000.hdmi (ops
>>>>>>> 0xc1398690): -1
>>>>>> Umm, -1 ?  Looking that error code up in
>>>>>> include/uapi/asm-generic/errno-base.h says it's -EPERM.
>>>>>>
>>>>>> I suspect that's someone just returning -1 because they're lazy...
>>>>>> which is real bad form and needs fixing.
>>>>> Oh, it really is -EPERM:
>>>>>
>>>>> struct exynos_drm_crtc *exynos_drm_crtc_get_by_type(struct drm_device
>>>>> *drm_dev,
>>>>>                                          enum exynos_drm_output_type
>>>>> out_type)
>>>>> {
>>>>>           struct drm_crtc *crtc;
>>>>>
>>>>>           drm_for_each_crtc(crtc, drm_dev)
>>>>>                   if (to_exynos_crtc(crtc)->type == out_type)
>>>>>                           return to_exynos_crtc(crtc);
>>>>>
>>>>>           return ERR_PTR(-EPERM);
>>>>> }
>>>>>
>>>>> Does "Operation not permitted" really convey the error here?  It doesn't
>>>>> look like a permission error to me.
>>>>>
>>>>> Can we please avoid abusing errno codes?
>>>> I tried 4.15-rc3 on odroid-xu4 after seeing drm issues reported. 4.15-rc2+
>>>> with top commit g968edbd worked just fine for me last Friday. I ran
>>>> several
>>>> tests and everything checked out except the exynos-gsc lockdep issue I
>>>> sent
>>>> a 4.14 patch for.
>>>>
>>>> However, with 4.15-rc3, dmesg is gets filled with
>>>>
>>>> [  342.337181] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  342.337470] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  342.337851] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.382346] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.396682] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.399244] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.399496] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.399848] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.400163] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.400495] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.401294] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>> [  402.401595] [drm] Non-contiguous allocation is not supported without
>>>> IOMMU, falling back to contiguous buffer
>>>>
>>>> Something broke in 4.15-rc3 on odroix-xu4 badly with exynos_defconfig.
>>>>
>>>> I will start bisect and try to isolate the problem. I suspect this is
>>>> related to dts
>>>> changes perhaps? I used to this problem a while back and it has been
>>>> fixed.
>>>
>>> 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.
> 

Good to know it doesn't break Exynos Snow. This is why I test without
IOMMU and then enable IOMMU on odroid-xu4 for test with IOMMU

thanks,
-- Shuah