Hello:
We are working on implementing driver for SCC operating in QMC mode that
supports multiple HDLC channels. The details of the system we are using
are the following.
CPU Version = 8247 based on 82xx family of processor(PVR 80822014)
The Linux OS Version = DENKS Linux version 2.4.20.
The Peripherals used are = FCC1 in 10/100 ethernet
FCC2 in 10/100 ethernet
SCC1 currently not used, but
proposed to be used in HDLC mode.
SCC3 is not used.
SCC4 operating in QMC mode
with super -channel capability. Trying to operate 192kbps HDLC channel
(using 3x64kbps QMC channels).
SMC2 in UART mode (as a
simple debug port without any modem signals).
SPI interface currently not
used but shall be used in future.
I2C is being used.
01. Can the channel specific parameters of the SCC4 in QMC mode be
relocated from DPRAM base address?? There is no mention in the
8272RM.pdf about configuring the base address of channel specific
parameters. From the QMC memory structure diagram, it looks like the
channel specific parameters will be taken from the the DPRAM base
address. Can you please confirm it?
02. We have changed the function m8260_cpm_dpalloc() used for DPRAM
allocation in the linux source code. It was allocating memory from
128Byte location to 8KByte location in DPRAM. But since QMC requires the
lower 4KByte for channel specific parameters, we changed the function to
allocate DPRAM from 4KByte location. Will this change lead to any
problem for proper linux operation?
03. We are encountering a strange problem with scc4 parameter RAM. When
the driver is coming up, its trying to initialize the SCC4 parameter RAM
for QMC. In the location (immr + 0x8318), we are writing the value
0x8320 but the value magically changes to 0x8300. We tried to write to
the location using BDI and again the problem is seen. Is this a known
problem with the processor?? This problem doesnot appear everytime. Is
there any known cause for this problem?
Regards,
Robin
