ide dma in latest cvs

ide dma in latest cvs

[Gerald Champagne]

Does the latest CVS version work with an IDE controller in DMA mode?

I have an NEC VR5432 based system working with the IDE controller, but it
crashes when used in dma mode.  I've tracked it down to the following code
called from ide_build_sglist():

- blk_rq_map_sg() is called to build a list of blocks to be transferred.
   It sets address = NULL for every entry (other fields like "page" are
   set to valid values).

- dma_cache_wback_inv(addr, size) is called for each block entry.  This
   routine crashes because the address parameter is always set to zero
   when the routine is called.

I see that this is part of the new bio code recently added.  Should I expect
this code to work, or is it not yet working for the mips platform?

Thanks.

Gerald

Re: ide dma in latest cvs

[Vivien Chappelier]

On Mon, 21 Jan 2002, Gerald Champagne wrote:

> - blk_rq_map_sg() is called to build a list of blocks to be transferred.
>    It sets address = NULL for every entry (other fields like "page" are
>    set to valid values).
> 
> - dma_cache_wback_inv(addr, size) is called for each block entry.  This
>    routine crashes because the address parameter is always set to zero
>    when the routine is called.
> 
> I see that this is part of the new bio code recently added.  Should I expect
> this code to work, or is it not yet working for the mips platform?

I've encountered a similar problem on O2. You can probably fix it by
adding the code for handling pages in 
pci_map_sg/pci_unmap_sg/pci_sync_sg. This is what I've done for ip32 and
ip27:

 unsigned long address;

 if(sg->address)
   address = sg->address;
 else
   address = page_address(sg->page) + sg->offset; 
 dma_cache_wback_inv(address, sg->length);


regards,
Vivien Chappelier.

Re: ide dma in latest cvs

[Jun Sun]

Gerald Champagne wrote:
> 
> Does the latest CVS version work with an IDE controller in DMA mode?
> 
> I have an NEC VR5432 based system working with the IDE controller, but it
> crashes when used in dma mode.  I've tracked it down to the following code
> called from ide_build_sglist():
> 
> - blk_rq_map_sg() is called to build a list of blocks to be transferred.
>    It sets address = NULL for every entry (other fields like "page" are
>    set to valid values).
> 
> - dma_cache_wback_inv(addr, size) is called for each block entry.  This
>    routine crashes because the address parameter is always set to zero
>    when the routine is called.
> 

Did you check what the address is and why it is zero?  It seems to me this
might be key ...

Jun

Re: ide dma in latest cvs

[Gerald Champagne]

> Did you check what the address is and why it is zero?  It seems to me this
> might be key ...


I see what the address is and why it's set to zero.  The address is the
address of a block of data to be transferred using dma, and it's set to
zero because the new interface in blk_rq_map_sg() passes parameters in a
page field instead an address field.  It looks like this is part of the
bio changes for 2.5 that work for x86 but haven't been updated for Mips.

I figured that someone else must have run into this and it sounds like
someone did.  I'll try what Vivien Chappelier recommended in his response.

Thanks.

Gerald