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From: Laurent Pinchart <laurent.pinchart@tbox.biz>
To: linuxppc-embedded@ozlabs.org
Subject: CPM_UART should allocate DPRAM for SMCx parameter RAM on MPC82xx
Date: Wed, 7 Jun 2006 14:34:08 +0200
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Hi everybody,

the move to platform devices introduced a bug in the CPM_UART SMC driver.

Unlike SCC and FCC, the SMC parameter ram is not at a fixed location. A 
pointer to the parameter ram is instead stored at PROFF_SMCx_BASE.

The SMC platform device resources (in arch/ppc/syslib/pq2_devices.c) reserves 
the memory resource PROFF_SMCx_BASE - PROFF_SMCx_BASE+1. The CPM UART driver 
considers that value as the SMC parameter ram offset. It should instead 
allocate 64 bytes (on a 64 bytes boundary) of DPRAM for its parameter ram, 
and store the offset at PROFF_SMCx_BASE. 

I'm not sure how to fix the problem as it seems that the platform device 
support is not complete yet (cpm_uart_init_portdesc is still used to 
initialize the console). A possible workaround is to set the pram resource to 
0x0000-0x003f and 0x0040-0x007f instead of 0x87fc-0x87fd and 0x88fc-0x88fd 
for SMC1 and SMC2. This will not work if cpm_uart_init_portdesc is not 
called.

Laurent Pinchart