Revert "ARM: socfpga: Remove socfpga_sdram_apply_static_cfg()

[Wolfgang Grandegger]

Am 06.08.20 um 14:50 schrieb Marek Vasut:
> On 8/6/20 2:36 PM, Wolfgang Grandegger wrote:
>> Am 06.08.20 um 13:04 schrieb Marek Vasut:
>>> On 8/6/20 12:53 PM, Wolfgang Grandegger wrote:
>>>> This reverts commit c5f4b805755912a3d2fe20f014b6b6ab0473bd73.
>>>>
>>>> Conflicts:
>>>> 	arch/arm/mach-socfpga/misc_gen5.c
>>>>
>>>> Without socfpga_sdram_apply_static_cfg(), the system hangs when Linux
>>>> calls altvipfb2_start_hw() of the Intel Video and Image Processing(VIP)
>>>> Frame Buffer II driver (drivers/video/fbdev/altvipfb2.c)
>>>
>>> There is no such driver in mainline U-Boot or Linux.
>>
>> It's a simple frame buffer driver from linux-socfpga for the IP core
>> Intel Video and Image Processing(VIP) Frame Buffer II. It actually
>> hangs here when the streaming starts:
>>
>> https://github.com/altera-opensource/linux-socfpga/blob/socfpga-5.4.44-lts/drivers/video/fbdev/altvipfb2.c#L69
>>
>> I can also hang the system if I setup and start the FB with just a
>> few U-Boot commands. I think the system hangs when the IP core starts
>> reading the FB data from the system memory.
> 
> I am CCing Dinh , I recall there was some discussion about hangs on
> CycloneV and it was fixed recently.
> 
>>>> , but only
>>>> after a power cycle (cold boot). The issue does not show up after a
>>>> soft reset (warm boot) and with v2018.11.
>>>
>>> See the commit message of the patch this is reverting, I believe there
>>> is a deeper issue with the static config register. Can you investigate?
>>
>> I read the commit message, but well, I can't follow all the details :(.
>> On the other hand, it seems also not clear why the fix was added. Any
>> idea what to investigate.
> 
> The system was repeatedly rebooted in a loop, the FPGA was loaded before
> Linux booted. After hundreds of reboots, the system got stuck on setting
> up the static cfg register. I think there was even another email

I rebooted Linux on my MCVEVP more than 100 times with and without
loading the FPGA in U-Boot. The system never hang!

> exchange where the suggestion was to make this apply_static_cfg optional
> and only use it when the DRAM port is enabled in the quartus design.
> Maybe that is the way out of this ?

Yep.

Wolfgang