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

Andreas Färber afaerber at suse.de
Fri Aug 1 05:13:01 PDT 2014

Hi 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:
>> 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
> Type of the bootloader should not matter unless its switching on
> FET1 and FET6 of tps65090 for you.
> But, config can be different!
> I have attached a config i used to get display with your latest
> spring-bridge.v6.
> Uncomment the DT nodes for DP and bridge chip and you should
> be able to get display and also the login.
> I think that you have not selected all the configs needed for IOMMU to
> work properly. When I deselected few IOMMU configs, I could see system
> crashing when FIMD + DP path was being initialized. May be, that is why your
> USB stops working. Even I have root file system on USB drive.

Find attached a diff between our configs. The following stand out:

* I have LPAE enabled
* you don't have DMA enabled
* I have CMA enabled (like in the new defconfigs)
* I have the arch timer disabled (which you suggested earlier for delay)
* I have more devices enabled (SPI, PWM, cpufreq, watchdog, ...)


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