Use Callbacks rather than RT_Support and avoid UpCall 6
Detail:
There are 2 elements in here, both of which have proven necessary to get the wifi drivers for Pi4b and PinebookPro working with the ROD stack. 1: Move the SDIO Card IRQ handling from RT_Support to CallBacks. This was essential as the RT_Support approach provided very limited IRQ throughput - This meant that interrupts were handled at the rate of the centisecond timer!! 2: In the 4 types of blocking R5Command calls the oriiginal used OS_UpCall 6 to provide yield and polling. Unfortunately this gave aborts - see below.
Use sdiolib_usermode_do_nothing, which is only called in svce mode irq on. Previous versions, using RT_Yield or OS_UpCall 6, would not happily return, and would cause aborts and hangs if the relevant SDIOLib code was invoked from a task window context. This behaviour is the same using sdio_io (Pi4b) or sdmmc_io (PinebookPro)
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