netdev - RE: [PATCH 1/4] ucc_geth: Change private immrbar_virt_to

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Date:	Thu, 8 Feb 2007 13:52:37 +0800
From:	"Li Yang-r58472" <LeoLi@...escale.com>
To:	"Tabi Timur-B04825" <timur@...escale.com>,
	"Kumar Gala" <galak@...nel.crashing.org>
Cc:	<netdev@...r.kernel.org>, <linuxppc-dev@...abs.org>
Subject: RE: [PATCH 1/4] ucc_geth: Change private immrbar_virt_to_phys to generic iopa

> -----Original Message-----
> From: Timur Tabi [mailto:timur@...escale.com]
> Sent: Thursday, February 08, 2007 1:03 AM
> To: Kumar Gala
> Cc: Li Yang-r58472; netdev@...r.kernel.org; linuxppc-dev@...abs.org
> Subject: Re: [PATCH 1/4] ucc_geth: Change private immrbar_virt_to_phys
to generic
> iopa
> 
> Kumar Gala wrote:
> 
> > If its been mapped with ioremap() you know the physical address
already
> > so why do you need iopa().
> 
> That's what the original function immrbar_virt_to_phys() does.  We're
trying to
> get rid of it, because we thought is redundant with iopa().
> 
> static inline unsigned long immrbar_virt_to_phys(volatile void *
address)
> {
> 	if ( ((u32)address >= (u32)qe_immr) &&
> 			((u32)address < ((u32)qe_immr + QE_IMMAP_SIZE))
)
> 		return (unsigned long)(address - (u32)qe_immr +
> 				(u32)get_qe_base());
> 	return (unsigned long)virt_to_phys(address);
> }
> 
> get_qe_base() does a search of the OF tree the first time it's called.
> 
> Here's the code that calls immrbar_virt_to_phys():
> 
> 	out_be32(&ugeth->p_send_q_mem_reg->sqqd[i].bd_ring_base,
> 		 (u32) immrbar_virt_to_phys(ugeth->
> 					    p_tx_bd_ring[i]));
> 
> 
> Would it be better to replace this code with something like this:
> 
> out_be32(&ugeth->p_send_q_mem_reg->sqqd[i].bd_ring_base,
> 	get_qe_base() + ((void *) ugeth->p_tx_bd_ring[i] - (void *)
qe_immr));

No, we don't know if the BD ring is in MURAM or main memory as it is
configurable.  iopa() is best choice to handle both case, IMHO.

- Leo
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