Re: convert parisc to the generic dma-noncoherent code

[Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>]

On Sun, Jul 15, 2018 at 12:29:37PM -0400, John David Anglin wrote:
> On 2018-07-13 4:14 AM, Helge Deller wrote:
>> On 11.07.2018 17:34, Christoph Hellwig wrote:
>>> ping?  Any comments?
>> I applied those 3 patches on top of git head, and booted the
>> 32-bit kernel on a HP 715/64 (PCX-L) and a HP B160L (PCX-L2).
>> On both machines I had problems with those drivers which use
>> DMA (I checked specifically the lasi NIC card, which is the
>> main onboard NIC card in both machines).
>> Getting IP via DHCP was unreliable, pings on the same network
>> to both machines gave lost packets, login via ssh sometimes failed
>> and so on.
>>
>> So, there is definitively some cache-flush missing in this patchset.
> Possibly, the code should use flush_kernel_vmap_range() as it purges the 
> TLB entries used
> for the cache flush.  Some of the routines in pci-dma.c currently use it.

That might be worth a try and is already discussed in my description.

Also it might be good to check that the last patch really is the culprit,
I'm pretty certain it is, but a double check never hurts.