I have an issue every time I try to run GPU. My system is iWave Q7 i.mx6 quad, bsp is based on 4.0.0 from freescale. Basically, I always have the same issue - output image on the HDMI is black/white striped instead of being coloured, with a lot of artefacts. Sometimes it doesn't even start, just makes kernel panic with dumping the stack, starting with the following message:
kernel BUG at arch/arm/mm/dma-mapping.c:478!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
I can observe this with running OpenGL ES 1.1 examples from GPU SDK and also with Qt 4.8 examples (which uses OpenGL ES 2.0). DMA is doing something wrong here and I am not really sure what.
I will post an image of these artefacts a bit later today.
Does anyone have similar issues? How can this be resolved?
I have an issue with Freescale i.MX6 Quad/DualLite. I'm not sure whether the problem is caused by the GPU but it is a potential possibility.
During run time we turn on/off the backlight of a 7" display. Randomly we have the situation that the display shows only half of the picture. You can see this in the attachment.
Does anyone have experience with stuff like that, or has anyone an idea what else could cause this issue.
I've already measured the backlight VCC and PWM. Looks good in my opinion.
Following display is used: TITLE : HV070WS1-105 by HYDIS.
Would be great if someone could get my more hints or ideas to fix this issue.
Thanks for reply - maybe it's not really clear from my post - the BSP is from iWave, r1.3, which is based upon Freescale's 4.0.0 Linux BSP. There are some modifications done for IPU and some custom drivers added, however they have nothing to do with system DMA or GPU - this is still in stock mode. So something in the BSP is not right.
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Here are the pictures - basically, everything is vertically striped. It's better seen on the first image. Also, it's not really possible to see or make a photo of but the left part of the image is flickering. So basically, as if there is some misalignment either with pixel format or with DMA. Or both for that matter...
Anyone has a clue?
I have a small update regarding this issue - in new BSP from iWave r1.4 (based upon freescale 4.1.0), it seems that kernel panic is gone, as I can start all the examples normally. However, stripes are still there. I will try to recompile the gpu code and see if there are changes (as I'm using binaries from previous build). The examples also do not crash, so I guess DMA problem is fixed.
I'll repost if I make any progress...