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5748 Discussions

Frame Buffer read stall

Honored Contributor I



I have a video system that connects a Frame Buffer component to the ALTMEMPHY using the MPFE (Multi-port Front End). 


Currently we are noticing that the Frame buffer gets in a state where it reads out the first two frames and then constantly gets stuck and drops frames. 


I can see that the MPFE is writing to memory but after 2 frames is stops reading. Does anyone know what would cause the Frame Buffer to stop reading frames? Is this an issue with the MPFE? 


The Frame buffer is encrypted so I can't examine the code.. 


As far as I can tell no upstream video blocks are asserting backpressure..  


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2 Replies
Honored Contributor I



Were you able to solve your problem? 


I have a similar-sounding issue with a Frame Reader connected to a UniPHY DDR2 controller via an MPFE.  


I based the Qsys settings on Altera's UDX5 reference design, so I configured the Frame Reader to be 256-bits wide, with a 128-deep FIFO and using 64-beat bursts. The memory controller also has a 256-bit wide interface and a max burst size of 64. 


Looking at the debug registers in the MPFE, it looks like the Frame Reader just stops reading data after a certain number of words (less than one frame). At the same time, the Clocked Video Out component that is connected to the Frame Reader is reporting an underflow condition. 


Thanks for any help you can offer.
Honored Contributor I

My problem was due to a configuration error: the frame reader needs to be configured with the number of memory-width (256-bits in my case) words per frame (register 5) and I was setting it to the number of 32-bit words per frame. Also, register 6 (number of single-cycle colour patterns per frame) needs to be set correctly.