Re: USB umass hard drive "failed to create xfers" when attaching

[sc.dying%gmail.com@localhost]

On 2020/03/19 07:10, Nick Hudson wrote:
> On 19/03/2020 07:05, sc.dying%gmail.com@localhost wrote:
>> On 2020/02/17 21:33, Nick Hudson wrote:
> 
> [snip]
> 
>>> xhci could do better and support multiple DMA segments, but uvm could
>>> also help.
>>
>> To access each DMA segment in usb_dma_t *dma, should it be processed
>> like this?
>>
>> for (i = 0; i < dma->udma_block->nsegs; i++) {
>> 	bus_dma_segment_t *ds = &dma->udma_block->map->dm_segs[i];
>>
>> 	process_segment(ds->ds_addr, ds->ds_len);
>> }
> 
> I started looking into this and have some changes to fix [ou]hci.
> xhci and dwc2 seem to be a bit harder.

dwc2 is a Greek to me.

> http://src.illumos.org/source/xref/netbsd-src/sys/dev/usb/ehci.c#3011
> 
> Is how ehci currently does it.

I've read that part of echi, but I cannot make me understood completely.
Does ehci always split the transfer into 4kB chunks even
it is physically contiguous?

> 
> Nick
>