Re: + fix-ide-dma-resource-managment.patch added to -mm tree

[Sergei Shtylylov <sshtylyov@ru.mvista.com>]

Hello.

Sergei Shtylylov wrote:

> Bartlomiej Zolnierkiewicz wrote:

[skipped]

>>> Resolve several IDE DMA resource management issues:

>>> - release DMA engine for memory mapped DMA as well

>> NAK - this won't work, see siimage.c how these resources were
>> really reserved in the first place [ request_mem_region() ]

    NB: it's reserved this way only when available -- this driver can work 
with both I/O and memory mapped regs...

>    Oops, looks like I missed that missing ide_setup_dma() call in that 
> driver...

    No, I've just forgotten that it's called implicitly from setup-pci.c since 
init_dma() "method" in not defined in that driver. So, looks like you're wrong 
here -- it should work currently BUT the DMA engine is not released since 
(mmio == 2) check and return precedes call to ide_release_dma_engine() in 
ide_release_dma().
    And as I said, there's no provision to release any driver-specific 
resources on a call to ide_release_dma()...

[skipped]

>> hwif->mmio == 2 means that host driver is responsible
>> for reserving/releasing resources (this is _preferred_ way
>> of handling resources)

>    Hm, didn't know that...

    ... and this was hard to guess from the current code. ;-)

>> please fix trm290.c to use ->mmio == 2 instead

>    It's a _really_ old chipset (pre SFF-8038i) and has _no_ memory 
> mapped regs AFAIK...

    The only thing that can be done is not to call ide_setup_dma() from it...

>>> - release the channel's secondary DMA I/O ports for real

>> NAK, looking and the code - secondary DMA base is only used
>> by siimage.c and sgiioc4.c (both use ->mmio == 2, for siimage ->dma_base2
>> is unused, for sgiioc4 it is used for some weird DMA transfer ending 
>> stuff)

>    Yes, I have sgioc4.c patch that deals with this (almost) ready...

    ... and for siimage, this seems a no-brainer. :-)

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WBR, Sergei