Re: [PATCH 3/5] add sg segment limitation info to device structure

Jeff Garzik
2007-10-03T17:59:04Z

FUJITA Tomonori wrote:
> On Tue, 2 Oct 2007 09:44:13 -0700
> Greg KH <gregkh@suse.de> wrote:
>
>> On Tue, Oct 02, 2007 at 09:25:34AM -0600, Matthew Wilcox wrote:
>>> On Tue, Oct 02, 2007 at 05:23:39PM +0200, Kay Sievers wrote:
>>>> Just looking at the number of devices, it seems that allocating it
>>>> dynamically would be the better deal. We allocate the name of every
>>>> kobject dynamically today, so I guess it's fine to do that with the
>>>> DMA data too.
>>> But we don't need to allocate it dynamically. We can embed it in the
>>> pci_dev, eisa_dev, zorro_dev, mca_dev and parisc_device.
>> But then you run into the issue that James pointed out originally.
>>
>> Anyway, I don't care which, let's see some patches :)
>
> How about this (based on James' proposal)?
>
> - Currently, there are only max_segment_size and segment_boundary_mask
> in struct device_dma_parameters (I'll add segment_boundary_mask
> support later after I finish the iommu part). We'll move more dma
> stuff in struct device (like dma_mask) to struct device_dma_parameters
> later (needs some cleanups before that).
>
> - New accessors for the dma parameters are added. So we can easily
> change where to place struct device_dma_parameters in the future.
>
> - the default max_segment_size is set to 64K, same to the block
> layer's default value.

ACK