Etnaviv issues on i.MX8M-Mini

Tue Mar 3 16:27:41 UTC 2020

On 03.03.20 16:59, Guido Günther wrote:
> Hi,
> On Tue, Mar 03, 2020 at 11:43:14AM +0000, Schrempf Frieder wrote:
>> On 02.03.20 09:44, Frieder Schrempf wrote:
>>> On 26.02.20 17:05, Guido Günther wrote:
>>>> On Wed, Feb 26, 2020 at 04:54:35PM +0100, Lucas Stach wrote:
>>>>> On Mi, 2020-02-26 at 15:31 +0000, Schrempf Frieder wrote:
>>>>>> On 25.02.20 09:13, Frieder Schrempf wrote:
>>>>>>> Hi Lucas,
>>>>>>>
>>>>>>> On 24.02.20 12:08, Lucas Stach wrote:
>>>>>>>> On Mo, 2020-02-24 at 10:53 +0000, Schrempf Frieder wrote:
>>>>>>>>> Hi Lucas,
>>>>>>>>>
>>>>>>>>> On 24.02.20 11:37, Lucas Stach wrote:
>>>>>>>>>> Hi Frieder,
>>>>>>>>>>
>>>>>>>>>> On Mo, 2020-02-24 at 10:28 +0000, Schrempf Frieder wrote:
>>>>>>>>>>> On 20.02.20 19:58, Chris Healy wrote:
>>>>>>>>>>>> For the jerkey transitions, can you determine if this is a
>>>>>>>>>>>> symptom of
>>>>>>>>>>>> a low framerate or dropped frames or something else?
>>>>>>>>>>>>
>>>>>>>>>>>> Perhaps you can start your app with
>>>>>>>>>>>> "GALLIUM_HUD=fps,cpu,draw-calls,frametime".  This may give some
>>>>>>>>>>>> clues.
>>>>>>>>>>>
>>>>>>>>>>> The framerate seems ok. I get something between 50 and 70 FPS.
>>>>>>>>>>>
>>>>>>>>>>> I have a Qt demo app with a menu and an animated 'ball' that moves
>>>>>>>>>>> across the screen. When the menu is visible, the ball movement is
>>>>>>>>>>> really
>>>>>>>>>>> jerky (ball seems to 'jump back and forth' instead of moving
>>>>>>>>>>> linearly).
>>>>>>>>>>>
>>>>>>>>>>> As soon as I hide the menu and show the animation fullscreen, the
>>>>>>>>>>> movements are perfectly smooth.
>>>>>>>>>>>
>>>>>>>>>>> Running the same app with software rendering, everything looks
>>>>>>>>>>> good, too.
>>>>>>>>>>>
>>>>>>>>>>> No idea what that means, though. I probably need to look at the
>>>>>>>>>>> code of
>>>>>>>>>>> the app and do some more experiments to get a better idea of what
>>>>>>>>>>> might
>>>>>>>>>>> cause the distortion.
>>>>>>>>>>>
>>>>>>>>>>> Unless some of the graphics experts here already have an idea
>>>>>>>>>>> of what
>>>>>>>>>>> can cause and/or how to debug such an issue!?
>>>>>>>>>>
>>>>>>>>>> Which driver is used for the display side? It seems like the
>>>>>>>>>> display
>>>>>>>>>> side doesn't properly handle the dma fences used to synchronize
>>>>>>>>>> scanout
>>>>>>>>>> and rendering.
>>>>>>>>>
>>>>>>>>> I ported/picked the drivers for the LCDIF and DSI controllers from
>>>>>>>>> development branch of the 5.4-based vendor kernel [1] to our own
>>>>>>>>> v5.4-based kernel [2]. So it is quite probable, that something
>>>>>>>>> could be
>>>>>>>>> wrong here.
>>>>>>>>
>>>>>>>> Please just use DRM_MXSFB for the display side, instead of the
>>>>>>>> downstream driver.
>>>>>>>
>>>>>>> Hm, good idea. I somehow forgot about the fact, that there is an
>>>>>>> upstream driver for the LCDIF controller. On first try I couldn't
>>>>>>> get it
>>>>>>> to run on the i.MX8MM, but I suspect that's due to some reset,
>>>>>>> power-domain or clock setup, that is missing upstream. I will see if I
>>>>>>> can get any further with this.
>>>>>>
>>>>>> So I had a closer look and while the DRM_MXSFB looks ok on its own, I
>>>>>> have some problem with the rest of the i.MX8MM display subsystem.
>>>>>>
>>>>>> The vendor stack, that I'm currently using integrates into the imx-drm
>>>>>> master/core driver [1] that binds all the components of the display
>>>>>> subsystem, such as the LCDIF driver and the integrated SEC_DSIM DSI
>>>>>> bridge.
>>>>>>
>>>>>> And because of my lack of DRM skills, I have no idea how to get the
>>>>>> DRM_MXSFB driver to bind to the imx-drm core, instead of running
>>>>>> separately and connecting directly to some panel as it is done for
>>>>>> i.MX23/28 and i.MX6SX/UL.
>>>>>
>>>>> It's a separate hardware and it's a pretty major design issue of the
>>>>> downstream driver that it integrates into imx-drm. You don't want this
>>>>> with the upstream driver.
>>>>>
>>>>> Maybe Guido (CCed) can give you some clues, as apparently he is using
>>>>> the mainline eLCDIF driver + some patches to drive the DSI display path
>>>>> on i.MX8MQ. A lot of this will probably be transferable to the i.MX8MM
>>>>> display path.
>>>>
>>>> Newer mxsfb supports attaching a bridge so if you make your DSI host
>>>> controller driver a DSI bridge mxsfb can drive it:
>>>>
>>>>        
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/mxsfb/mxsfb_drv.c#n268
>>>>
>>>>
>>>> this should be similar to what was done for the imx8mq here (imx8mm
>>>> users a different ip core though):
>>>>
>>>>        
>>>> https://source.puri.sm/guido.gunther/linux-imx8/commits/forward-upstream/next-20200217/mxsfb+nwl/v9-wip
>>>>
>>>>
>>>> There's also some additional mxsfb patches by Robert floating around
>>>> which aren't mainline yet which the above branch also has.
>>>>
>>>> Which reminds me that i need to prepare and send out a v9.
>>>
>>> Thanks Lucas and Guido for pointing out the details!
>>> It's very unfortunate that i.MX8MQ and i.MX8MM don't share the same DSI
>>> ip core.
>>> It seems like I need to try coming up with a bridge driver for the
>>> Samsung DSIM DSI controller for a proper upstream solution.
>>
>> Sorry to bother you with one more question from a DRM newbie.
>>
>> I'm currently looking at Guido's code for the NWL DSI bridge and trying
>> to convert the NXP SEC DSIM host driver to a bridge driver.
>>
>> The NWL driver uses mipi_dsi_host_register(), which searches for a
>> output (panel) child node under the DSI bridge's node [1] as described
>> in the bindings example [2].
>>
>> How is this supposed to work in a setup with another bridge after the
>> DSI bridge, where that bridge is not a child node of the DSI bridge, but
>> only connected via the DSI bridges output port? For example I have a
>> DSI->LVDS bridge, that is attached to an I2C port.
> 
> You can also attach another bridge instead of a panel. NXPs BSP uses a
> driver very similar to the nwl one above and this is how they attach a
> DSI->HDMI bridge:
> 
>      https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mq-evk-lcdif-adv7535.dts?h=imx_5.4.0_8dxlphantom_er#n56

Ok, I understand how this is supposed to work, as here drm_bridge_add() 
is called from probe() in the NWL bridge driver. But in your NWL driver, 
drm_bridge_add() is called from nwl_dsi_host_attach() and I currently 
fail to understand how this is supposed to work.

But don't mind, I figured out that difference now and call 
drm_bridge_add() from probe() in my driver. There's still a lot of other 
things I need to understand and in fact I'm not even sure if I have 
enough time to immerse myself much deeper.

Thanks,
Frieder