linux-kernel - Re: Linux-next, Exynos Octa boot fail, bisected to: "drm/exynos: remove drm_iommu_attach_device_if

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Message-id: <55AF52BF.4030201@samsung.com>
Date:	Wed, 22 Jul 2015 17:22:23 +0900
From:	Inki Dae <inki.dae@...sung.com>
To:	Joonyoung Shim <jy0922.shim@...sung.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Seung-Woo Kim <sw0312.kim@...sung.com>
Cc:	dri-devel@...ts.freedesktop.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: Linux-next, Exynos Octa boot fail,
 bisected to: "drm/exynos: remove drm_iommu_attach_device_if_possible"

On 2015년 07월 22일 17:12, Joonyoung Shim wrote:
> On 07/22/2015 01:55 PM, Inki Dae wrote:
>> On 2015년 07월 22일 11:02, Joonyoung Shim wrote:
>>> On 07/21/2015 10:19 PM, Krzysztof Kozlowski wrote:
>>>> Hi,
>>>>
>>>> Today's linux-next (next-20150721) encounters boot failures on Exynos
>>>> Octa (Exynos5422) based boards. The boards hangs. I bisected it to:
>>>>
>>>> d80167b85024982c5f18d0481a5c248100360118 is the first bad commit
>>>> commit d80167b85024982c5f18d0481a5c248100360118
>>>> Author: Joonyoung Shim <jy0922.shim@...sung.com>
>>>> Date:   Thu Jul 2 21:49:39 2015 +0900
>>>>
>>>>     drm/exynos: remove drm_iommu_attach_device_if_possible
>>>>
>>>>     Already drm_iommu_attach_device checks whether support iommu internally.
>>>>     It should clear channels always regardless iommu support. We didn't know
>>>>     because we can detect the problem when iommu is enabled, so we don't
>>>>     have to use drm_iommu_attach_device_if_possible and then we can remove
>>>>     drm_iommu_attach_device_if_possible and clear_channels function pointer.
>>>>
>>>>     Signed-off-by: Joonyoung Shim <jy0922.shim@...sung.com>
>>>>     Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
>>>>     Signed-off-by: Inki Dae <inki.dae@...sung.com>
>>>>
>>>> :040000 040000 83379efbf4960f58d680371628ec04387935bd53
>>>> da03c338b88e7cb6bda895b3dd52d78d9b6eba30 M drivers
>>>>
>>>>
>>>> Config: exynos
>>>> Boot log from Odroid XU3-Lite attached.
>>>>
>>>> Any hints or ideas?
>>>
>>> The point that hangs is when accesses fimd register in
>>> fimd_clear_channels function, so i doubt clock setting for fimd.
>>>
>>> It's gone something that hangs after i enable gating for ACLK_200_DISP1
>>> clock.
>>>
>>> If ACLK_200_DISP1 clock needs for fimd really, i'm thinking how can it
>>> support. Any ideas?
>>
>> I think bootloader should have enabled ACLK_200_DISP1 clock and also
>> device driver should enable all relevant clocks before the device
>> accesses its own registers.
>>
>> Best way would be that the clock is enabled by common clock framework
>> but it seems there is no anything that the clock framework can do it. So
>> I think what we have to do is to add the clock support to device tree.
> 
> It's not easy problem to me. Should we add which clock? I think we
> cannot control ACLK_200_DISP1 or CLKDIV2_DISP1_BLK directly by below
> hierarchy, right? Then we should control gate clocks, but we have not
> controlled any gate clocks using BTS_ prefix.
> 
> The clock hierarchy from Exynos5422 user manual,
> ACLK_200_DISP1 -- CLKDIV2_DISP1_BLK -- HDMI LINK
>                                        HDMI PHY
>                                        MIC1
>                                        DSIM1
>                                        DPTX LINK
>                                        MDNIE1
>                                        SYSMMU_MIXER
>                                        SYSMMU_FIMD1_M0
>                                        SYSMMU_FIMD1_M1
>                                        BTS_TVM0
>                                        BTS_TVM1
>                                        BTS_FIMD1_M0
>                                        BTS_FIMD1_M1
> 
> Other way, IMHO, fimd driver doesn't have to enable ACLK_200_DISP1 clock,
> just it should be controlled by connector drivers, e.g. dsi, dp because
> fimd only cannot operate, so dsi or dp must need (Actually i'm not sure
> about this, just i thought that Exynos5 SoCs don't have any gpios for
> dpi, so they cannot use dpi, right?).
> 
> It needs to probe connector driver like dsi or dp earlier than fimd and
> fimd_bind function should return error if connector driver like dsi or
> dp was not probed. This is also not easy to me.

In this case, if one of above gate clocks is enabled, the ACLK_200_DISP1
should be enabled. So I guess the problem would be due to below line of
clk-exynos5420.c,

GATE(CLK_FIMD1, "fimd1", "aclk300_disp1", GATE_IP_DISP1, 0, 0, 0),

Can you check it again after modifying it like below?,
GATE(CLK_FIMD1, "fimd1", "aclk200_disp1", GATE_IP_DISP1, 0, 0, 0),

Thanks,
Inki Dae

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