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/driv...
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/nex...
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