Messages in this thread | | | Date | Tue, 25 Sep 2007 14:09:03 +0200 | From | Jochen Friedrich <> | Subject | Re: [PATCH4/4] [POWERPC] Fix cpm_uart driver |
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Hi Scott, > Yikes. Please don't change cpm_uart_cpm1.h, as it's correct for > arch/powerpc, and there are numerous other places that assume cpmp is > virtual (including in the very same function that assigns it a > physical address).
I'm still not convinced cpm_uart_cpm1.h is correct:
pinfo->rx_bd_base and pinfo->tx_bd_base are both initialized with an address obtained by cpm_dpram_addr(). In both ppc and powerpc, this is an address relative to dpram_vbase in commproc.c
In cpm_uart_core.c, the operation "pinfo->rx_bd_base - DPRAM_BASE" is used to calculate the DPRAM offset. So DPRAM_BASE must be relative to dpram_vbase in commproc.c as well. However, cpm_uart_cpm1.h uses cpmp in commproc.c to initialize DPRAM_BASE.
On ARCH=ppc, cpmp is a physical address with 1:1 virtual mapping ("well known address"). On ARC=powerpc, this is an address obtained by ioremap(), however it's a different ioremap() call than dpram_vbase is obtained from, so noone can guarantee cpmp is always the same as dpram_vbase even on ARCH=powerpc.
To me, it looks like setting DPRAM_BASE to cpm_dpram_addr(0) is the fix as it makes the DPRAM offset a defined result.
Thanks, Jochen
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