Hello.
Bartlomiej Zolnierkiewicz wrote:
The patch titled
Fix IDE DMA resource managment
has been added to the -mm tree. Its filename is
fix-ide-dma-resource-managment.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
From: Sergei Shtylylov <sshtylyov@xxxxxxxxxxxxx>
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() ]
Oops, looks like I missed that missing ide_setup_dma() call in that driver...
Is there any point at all in handling mmio == 2 case in ide-dma.c then?
The only function that should handle this seems ide_release_dma() but in case
of MMIO there's _no_ provision for the proper driver cleanup (assuming it
allocates everything it needs by itself)... and, if the driver allocates the
engine of the different size that PDC_BYTES * PRD_ENTRIES (the case with
sgiioc3.c), the engine release doesn't look consitent...
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...
please fix siimage.c and core code instead
(please see libata-core.c and ata_host_stop() etc.)
- release the same number of DMA I/O ports that was requested by a driver
NAK, it should be always 8 - the only driver which does something different
is trm290.c and now looking at it, it seems broken since early 2.5.x
Why then the argument to ide_setup_dma() is needed at all?
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...
- 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...
so all of ->dma_base2 handling code in ide-dma.c is just a dead code
and should be removed
OK...
- claim extra DMA I/O ports regardless of what IDE channels are present/enabled
NAK, this change makes extra DMA I/O ports being reserved twice
No. Please review the patch carefully. This was tested OK on both channels
and secondary only channel.
- merge the duplicate code into ide_dma_iobase()
NAK, some of this code is irrelevant for MMIO (ie. ->dma_extra)
But it was duplicated anyway...
Please rework your changes and split them on separate patches
(IDE code is quite difficult - making changes in small steps really
helps).
Er... I'll try to.
Thanks,
Bartlomiej
WBR, Sergei
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