Revert "ARM: socfpga: Remove socfpga_sdram_apply_static_cfg()

[Marek Vasut]

On 8/7/20 1:22 PM, Wolfgang Grandegger wrote:
> 
> 
> Am 07.08.20 um 13:12 schrieb Marek Vasut:
>> On 8/7/20 12:58 PM, Wolfgang Grandegger wrote:
>>> 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!
>>
>> It could very well be bitstream related, wait for Simon to chime in.
>> Do you load the bitstream in U-Boot or in Linux ?
> 
> I load it in U-Boot. And I repeated the test more than 1000 times (100
> above is a typo)! OK, let's wait for more input.

Sorry for pushing back on this, the issue keeps coming back and until we
get to the bottom of this, I don't want to see applying and reverting a
patch back and forth. And getting to the real bottom of this seems to be
particularly difficult task.

Does your bitstream use the DRAM bridge (F2S) ? I think it does. The one
I used didn't as far as I remember. So maybe the way forward is to only
apply static cfg if the bridge is enabled.