[PATCH V6 0/8] drm/exynos: few patches to enhance bridge chip support

[Andreas Färber]

Ajay,

Am 01.08.2014 09:02, schrieb Ajay kumar:
> On Thu, Jul 31, 2014 at 7:52 PM, Andreas Färber <afaerber at suse.de> wrote:
>> Am 31.07.2014 12:23, schrieb Thierry Reding:
>>> On Thu, Jul 31, 2014 at 10:57:55AM +0200, Andreas Färber wrote:
>>>> Am 31.07.2014 10:38, schrieb Ajay kumar:
>>>>> With just the spring-bridge.v6 branch of your own tree, I am able to see
>>>>> bootup logo on Skate(a variant of spring which also contains ps8622).
>>>>> I have tried both exynos_defconfig and multi_v7_defconfig.
>>>>> I enable DRM, EXYNOS DRM, BRIDGE CHIPS, IOMMU, EXYNOS IOMMU
>>>>> in configs.
>> [...]
>>> If you have something like simplefb enabled in addition to a DRM driver,
>>> then perhaps the DRM driver isn't properly taking over the framebuffer
>>> console.
>>
>> So, with simplefb reverted in U-Boot and ...
>>
>> * with just the v6 applied (...~2), I get only a black screen from
>> Linux, no penguins, but the backlight seems on. System comes up okay,
>> ssh available, and nothing stands out in dmesg.
>>
>> * with the two iommu patches on top, something breaks badly, no
>> backlight, no USB/network, system inaccessible.
>> I.e. U-Boot had no noticeable impact on these symptoms.
>>
>> * with the iommu patches, but dp-controller, ps8622, panel commented
>> out, I do get backlight but USB/network not working, system inaccessible.
>>
>> With simplefb support in U-Boot and with just v6 applied, but
>> dp-controller, ps8622, panel commented out, things work as well as
>> before, i.e. this series has no bad side effects. Note that I never
>> claimed Ajay's series were broken, just reported that things regressed
>> for me from v4, which may well be DT-related.
>>
>> The iommu patches interfere with my USB somehow (none or not all devices
>> powered; with v4, plugging my wifi dongle led to oops but ethernet
>> dongle worked, so not entirely new symptom), which is bad since my
>> rootfs is on USB. The internal SDIO-connected Wifi is not enabled yet,
>> so USB based network is my only alternative to a working display once we
>> reach userspace.
> Well, there are 2 variants here:
> 1) Bootloader
> 2) config

Unfortunately your config doesn't work for me either, on my latest
spring-bridge.v6 branch.

> Type of the bootloader should not matter unless its switching on
> FET1 and FET6 of tps65090 for you.

It does switch them on, if I'm reading correctly:

https://github.com/afaerber/u-boot/blob/spring/board/samsung/smdk5250/smdk5250.c#L599

https://github.com/afaerber/u-boot/blob/spring/board/samsung/smdk5250/smdk5250.c#L907

Another observation I made is that sometimes in my testing (didn't spot
a pattern yet) after reboot or power-off/power-on the initial white
screen with the warning did not come up (no backlight), but Ctrl+U
worked fine and chain-loaded nv u-boot came up on screen okay.

Andreas

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