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foss-for-synopsys-dwc-arc-processors / openocd

The development tree for OpenOCD for the Synopsys DesignWare ARC processor family
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Reading JTAG status after writing register/memory makes an extra write #39

Open EvgeniiDidin opened 5 years ago

EvgeniiDidin commented 5 years ago

According to Databook we need to check transaction status after memory/register reads and writes by reading JTAG status register. This is made by code added by this commit: https://github.com/foss-for-synopsys-dwc-arc-processors/openocd/commit/42deccc106e826778d6b585291ebbda655ebbdfe

But currently this code is not running due incorrect JTAG module behaviour. For more information how to reproduce incorrect behaviour see STAR 9000833244.

For upstreaming it is not good to add code, which is never running. But we don't want to forget these changes, when fix in HW appears, this commit should be applied.

EvgeniiDidin commented 5 years ago

There is a good code, which checks if JTAG is ready to perform memory/registers r/w. Currently it is disabled, but may be used for debug purposes: https://github.com/foss-for-synopsys-dwc-arc-processors/openocd/commit/db1bbc7a1f3d54570b63ab8efd7b553a1f758202