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

[m.szyprowski@samsung.com (Marek Szyprowski)]

Hi Shuah,

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.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland