Display Resolution Problems with EC7 BSP (02.30.00) on AM335x

Greg Sulfid

Hello,

I use an external display on the LCD port. With the fixed and default resolution of the BSP (800x480) there is no problem, but when I use 800x600 I have strange artefacts (see attached pictures). This could not be a problem with the display resolution itself, because the mouse will be displayed at every position on the display correctly. But perhaps something with the 2D accelerator configuration (framebuffers)? Seems that the position of the displayed information is on wrong memory positions? The half black file icons on the first picture are from the explorer session before (after closing).

Anyone an idea?

Thanks ahead!

over 12 years ago

0 Renjith Thomas over 12 years ago

Guru 31670 points

What kind of display are you using? Is it raster LCD type or LIDD type? If its raster type, then please share the panel name, the pixel clock rate supplied, and VSYNC frequency?

0 Greg Sulfid over 12 years ago in reply to Renjith Thomas

Intellectual 610 points

Thank you very much for your fast answer. We have attached this HDMI chip at the AM335x: http://www.siliconimage.com/products/product.aspx?pid=150

I don't think, that this has anything to-do with the pixel clock nor VSYNC or HSYNC, at least, as we use the same values under Linux and there we have no problems with other resolutions. Generally the display shows everything at its right position - so it did for the mouse pointer, or when I click on the start menu and go trough its menus (no damaged view or wrong position for it).

Any ideas?

0 Renjith Thomas over 12 years ago in reply to Greg Sulfid

Guru 31670 points

Greg,

Since you are using SiI9022a HDMI transmitter, did you read the EDID information from the panel and saw whether it supports 800x600 resolution?

0 Greg Sulfid over 12 years ago in reply to Renjith Thomas

Intellectual 610 points

Yes, it did - and under Linux no problem with 800x600 - it also shows that its working under 800x600 on the OSD. We've also tried different displays and also one with native 800x600.

0 Renjith Thomas over 12 years ago in reply to Greg Sulfid

Guru 31670 points

Are you configuring the timings (HFP, HBP, HSYNC, VBP, VFP and VSYNC) based on the EDID information?

Greg Sulfid said:
it also shows that its working under 800x600 on the OSD

What is the refresh/frame rate that is printed on OSD in this case?

0 Greg Sulfid over 12 years ago in reply to Renjith Thomas

Intellectual 610 points

Yes and the refresh rate is 63Hz@800x600- with the original and functional 800x480 resolution it shows 62Hz.

0 Greg Sulfid over 12 years ago in reply to Greg Sulfid

Intellectual 610 points

Sorry, this display messed up something. When we use the original timing values from the 800x480 resolution for 800x600, we get stable informations on the screen. A little bit weird but now we have the place to take a look at. The HDMI transceiver seems to work more complex then we thought. Thanks!

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Display Resolution Problems with EC7 BSP (02.30.00) on AM335x