[PATCH] [RFC] drm: mxsfb: Implement LCDIF scanout CRC32 support

[Marek Vasut]

On 2/10/22 06:22, Liu Ying wrote:

Hi,

[...]

>>>>>> There are many blank areas which are undocumented, this LCDIF
>>>>>> CRC32
>>>>>> feature, i.MX8M Mini Arteris NOC at 0x32700000 , the ARM GPV
>>>>>> NIC-
>>>>>> 301
>>>>>> at
>>>>>> 0x32{0,1,2,3,4,5,6,8}00000 and their master/slave port
>>>>>> mapping.
>>>>>> The
>>>>>> NOC
>>>>>> and NICs were documented at least up to i.MX6QP and then that
>>>>>> information disappeared from NXP datasheets. I think
>>>>>> reconfiguring
>>>>>> the
>>>>>> NOC/NIC QoS would help mitigate this shift issue described
>>>>>> below
>>>>>> (*).
>>>>>
>>>>> I also think the QoS would help if it is configureable.
>>>>
>>>> It is programmable, it's just the port mapping which is
>>>> undocumented.
>>>>
>>>>>> Do you know if there is some additional NOC/NIC documentation
>>>>>> for
>>>>>> i.MX8M
>>>>>> Mini available ?
>>>>>
>>>>> No.
>>>>
>>>> Can you ask someone internally in NXP maybe ?
>>>
>>> Maybe, you may try community.nxp.com, like the i.MXRT case.
>>
>> The community.nxp.com is unhelpful, the i.MXRT case it a good example
>> -- 
>> the solution to the problem has been found by the person who asked
>> the
>> question on their own, and elsewhere too.
> 
> AFAIK, there are questions answered by internal support team and RnD
> team at that community.  I personally take it as a resource to use.

Sure, here is a list of links to similar problem triggered by various 
people using the NXP BSP, neither of them in answered:

https://community.nxp.com/t5/i-MX-Processors/Image-shift-right-for-LVDS/td-p/969581
https://community.nxp.com/t5/i-MX-Processors/iMX8M-display-shifted-after-playing-decoded-video-with-gstreamer/td-p/928269
https://community.nxp.com/t5/i-MX-Processors/Display-Wrap-Around-Issue/td-p/1084052
https://community.nxp.com/t5/i-MX-Processors/Display-Vertically-shifted-IMX8mq-evk-board-in-dual-display-use/m-p/965726
https://community.nxp.com/t5/i-MX-RT/iMXRT1052-LCD-Screen-shifted/td-p/1069978

>> But note that the i.MXRT interconnect documentation is available in
>> the
>> i.MXRT datasheet, which made that possible in the first place. On
>> i.MX,
>> all that information has been removed from the datasheet in i.MX7
>> and
>> i.MX8M, so I cannot even help myself, even if I wanted to. This is
>> very bad.
> 
> I'm not familiar with the documention in that area, so I personally
> will not be helpful at the documention topic.  The main purpose I
> jumped in this thread is to review the patch and share the idea to use
> the existing drm debugfs crc support instead of creating a sysfs
> attribute.

Can you maybe ask someone inside NXP about this problem ?