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Date: Wed, 29 Jul 2009 13:46:02 +1000
From: Mark Ware <mware@elphinstone.net>
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To: Scott Wood <scottwood@freescale.com>
Subject: Re: [RFC/PATCH] powerpc: Don't use alloc_bootmem in cpm_uart_cpm2.c
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Scott Wood wrote:
> On Mon, Jul 20, 2009 at 09:51:03PM +1000, Mark Ware wrote:
>> This is another alloc_bootmem() -> kzalloc() change, this time to
>> fix the non-fatal badness caused when booting with a cpm2_uart console.
>>
>> Signed-Off-By: Mark Ware <mware@elphinstone.net>
>>
>> ---
>>  drivers/serial/cpm_uart/cpm_uart_cpm2.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/serial/cpm_uart/cpm_uart_cpm2.c 
>> b/drivers/serial/cpm_uart/cpm_uart_cpm2.c
>> index 141c0a3..a9802e7 100644
>> --- a/drivers/serial/cpm_uart/cpm_uart_cpm2.c
>> +++ b/drivers/serial/cpm_uart/cpm_uart_cpm2.c
>> @@ -132,7 +132,7 @@ int cpm_uart_allocbuf(struct uart_cpm_port *pinfo, 
>> unsigned int is_con)
>>  	memsz = L1_CACHE_ALIGN(pinfo->rx_nrfifos * pinfo->rx_fifosize) +
>>  	    L1_CACHE_ALIGN(pinfo->tx_nrfifos * pinfo->tx_fifosize);
>>  	if (is_con) {
>> -		mem_addr = alloc_bootmem(memsz);
>> +		mem_addr = kzalloc(memsz, GFP_NOWAIT);
>>  		dma_addr = virt_to_bus(mem_addr);
>>  	}
> 
> Hmm, is dma_alloc_coherent() now available this early as well?  If so, we
> could get rid of the separate "is_con" handling altogether.
> 
> -Scott
> 

This was my first thought as well, but calling dma_alloc_coherent() on a console resulted in a hang on boot before any console output.
I have no actual proof, but it seems likely that it is not available at that point in the boot.

Regards,
Mark