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Video latency and SDRAM arbitering
[1] For example because a misconfiguration caused by a software bug in Linux drivers or by malicious code injected by an attacker.
===Video latency and SDRAM arbitering===
Applications that are based on such a video processing chain, often have a performance requirement in terms of video latency [1]. For this reason the ''latency gauge'' module has been implemented. It is based on a bank of 32-bit 10ns-resolution timers that allows to measure this latency precisely. This bank - that is encapsulated in an IP - is accessible by PS via AXI-Lite bus in order to expose these measurements for offline manipulation and visualization on 7" display. Apart from the requirement [[#SR2|[SR2]]], the availability of two independent SDRAM banks provides an advantage in terms of performances too, in particular when video latency is a concern.This configuration, in fact, allows to isolate all the SDRAM traffic related to the video processing chain from all the other traffic originating either in PS or PL domain (i.e. the stream feeding 7" LCD, data read/written by Linux kernel and applications running of top of it, etc.). This solution simplifies management of concurrent SDRAM accesses dramatically, because video processing combined bandwidth requirement (there are four VDMAs accessing the memory) is much smaller than the (theoretical) bandwidth provided by the controller/SDRAM subsystem. However, this solution comes at the price of adding a dedicated chip that is interfaced to the FPGA bank #35 [2]. In the first version if the system,
unico banco di ram per riduzione costi ma più fragile
 
 
 
[1] In this context, video latency is the time a video frame takes to traverse the chain, from the input interface to the visualization device.
 
[2] Bank #35 is optimized for such connections, as described in detail [[Programmable_logic_(Bora)#Routing_information_2|here]].
==Future work==
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