Serial DMA Controller
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
18-9
18.3.2
SDMA and Bus Error
If a bus error occurs on an SDMA access from the QUICC Engine subsystem, the following
occurs:
1.
The QUICC Engine subsystem generates a unique maskable interrupt in the SDMA
status register (SDSR),
2.
The DSP core uses an interrupt service routine (ISR) to read the SDSR to determine
which bus generated the error.
3.
System recovery depends on how you configure the SDMR[SBER_1] bit. One of the
following occurs:
— The QUICC Engine subsystem disables the peripheral or thread associated with the
bus error and continues to operate as usual on all other peripherals (default). The
recovery sequence in this mode is based on re-initialization of the peripheral associated
with the error, or
— The QUICC Engine subsystem stops all activity, and must be reset through the reset
command to the QUICC Engine Command Register (CECR).
In general, it should be noted that the DSP core, depending on how it is programmed, may read
the SDMA address register (SDTA) to determine the address at which the bus error occurred, and
the SDMA SNUM register (SDTM) to determine which peripheral or thread was being serviced
by the SDMA virtual channel. See Table 18-3 for the list of SNUMs.
The SDTA and the SDTM registers store information related to accesses to the MBus. These two
registers are not updated with the address and SNUM of subsequent transactions as long as the
event bit in the SDSR is set.
18.3.2.1 Simple Recovery from Bus Error
The simplest recovery from a bus error is a QUICC Engine subsystem reset followed by an
overall QUICC Engine subsystem re-initialization procedure, regardless of the peripheral that has
actually caused the error. The reasoning is that for some applications, stopping one peripheral
leads to a chain reaction that ultimately disrupts the correct interworking operation of the QUICC
Engine subsystem. For debug purposes, it is valuable to observe continued operation, but a
selective recovery does not provide any added value. This non-distinctive procedure also reduces
the complexity of the recovery flow.
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...