[PATCH] drm/exynos: resolve infinite loop issue on multi-platform

[Inki Dae]

On 2014년 11월 06일 22:00, Krzysztof Kozlowski wrote:
> On czw, 2014-11-06 at 21:32 +0900, Inki Dae wrote:
>> On 2014년 11월 06일 21:11, Krzysztof Kozłowski wrote:
>>> On 06.11.2014 11:32, Inki Dae wrote:
>>>> This patch resolves temporarily infinite loop issue incurred
>>>> when Exynos drm driver is enabled and multi-platform kernel
>>>> is used by registering Exynos drm device object only in case
>>>> of Exynos SoC. So this patch will be replaced with more generic
>>>> way later.
>>>
>>> Does not help for Rinato board.
>>>
>>> On Rinato:
>>> -----------------------
>>> Failed to find PMU node
>>> Registering SWP/SWPB emulation handler
>>> mmc0: BKOPS_EN bit is not set
>>> mmc_host mmc0: Bus speed (slot 0) = 100000000Hz (slot req 100000000Hz,
>>> actual 100000000HZ div = 0)
>>> exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
>>> mmc0: new HS200 MMC card at address 0001
>>> platform exynos-drm: Driver exynos-drm requests probe deferral
>>> mmcblk0: mmc0:0001 F5X5MA 3.64 GiB
>>> mmcblk0boot0: mmc0:0001 F5X5MA partition 1 4.00 MiB
>>> exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
>>> mmcblk0boot1: mmc0:0001 F5X5MA partition 2 4.00 MiB
>>> platform exynos-drm: Driver exynos-drm requests probe deferral
>>> mmcblk0rpmb: mmc0:0001 F5X5MA partition 3 512 KiB
>>> exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
>>> platform exynos-drm: Driver exynos-drm requests probe deferral
>>>  mmcblk0: p1 p2 p3 p4 p5 p6 p7
>>> exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
>>> platform exynos-drm: Driver exynos-drm requests probe deferral
>>> exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
>>> platform exynos-drm: Driver exynos-drm requests probe deferral
>>>
>>> and so on...
>>> -----------------------
>>
>> Can you show me compatible string placed on top of exynos3250-rinato.dts
>> file? If the compatible has "samsung,exynos3" it should be no problem
>> with this patch. And the rinato dts file we posted to mainline has the
>> compatible string.
> 
> model = "Samsung Rinato board";
> compatible = "samsung,rinato-rev05", "samsung,exynos3250",
> "samsung,exynos3";
> 
> The problem is "samsung,exynos3" because the patch solves only issue on
> multiplatform kernel run on non-exynos board. It does not solve the
> problem on exynos board with DRM enabled but without all drivers.
> 

Right, if you disabled all kms drivers and enabled only non-kms drivers
then the infinite loop will occur. However, this should be handled in
separated issue because without this patch, same issue will occur.

> 
>>>
>>> I do not know whether it is related but Trats2 board cannot boot due to
>>> lockup after:
>>> [drm] Initialized drm 1.1.0 20060810
>>> (with or without the patch)
>>> https://lkml.org/lkml/2014/11/6/125
>>>
>>
>> hmm... it's strange because my trats2 board works well with this patch.
>> Which kernel did you test? And how can I reproduce above lockup?
> 
> Just boot up next-2014110{456} with kernel config attached in mentioned
> email.

It looks like other issue regardless of this patch. If the board dts
file includes compatible string that Exynos drm driver is checking then
Exynos drm driver has no any change - having same logic.

Thanks,
Inki Dae

> 
> Best regards,
> Krzysztof
> 
> 
> 
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