On Feb 8, 2007, at 12:48 AM, Li Yang-r58472 wrote:
-----Original Message-----
From: Kumar Gala [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 08, 2007 1:58 PM
To: Li Yang-r58472
Cc: Tabi Timur-B04825; netdev@vger.kernel.org; linuxppc-
[EMAIL PROTECTED]
Subject: Re: [PATCH 1/4] ucc_geth: Change private
immrbar_virt_to_phys
to generic
iopa
On Feb 7, 2007, at 11:52 PM, Li Yang-r58472 wrote:
-----Original Message-----
From: Timur Tabi [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 08, 2007 1:03 AM
To: Kumar Gala
Cc: Li Yang-r58472; netdev@vger.kernel.org; [EMAIL PROTECTED]
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.
Does MURAM behave differently than normal memory?
MURAM is a mmio region so it don't share the characteristic of main
memory that phy_addr = virt_addr - PAGE_OFFSET. While they can
both be
mapped through page table using iopa().
Right, so when do you know if you'll be using MURAM or normal
memory? Why not just keep around a token that is the physical
address at the point you make the decision of MURAM vs normal memory.
- k
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