[PATCH 1/3] powerpc/powernv: remove the unused pnv_pci_set_p2p function

Max Gurtovoy maxg at mellanox.com
Tue Jul 9 23:49:04 AEST 2019

Hi Greg/Christoph,
Can we leave it meanwhile till we'll find a general solution (for the upcoming kernel) ?
I guess we can somehow generalize the P2P initialization process for PPC and leave it empty for now for other archs.
Or maybe we can find some other solution (sysfs/configfs/module param), but it will take time since we'll need to work closely with the IBM pci guys that wrote this code.


-----Original Message-----
From: Christoph Hellwig <hch at lst.de> 
Sent: Thursday, May 23, 2019 10:53 AM
To: Frederic Barrat <fbarrat at linux.ibm.com>
Cc: Christoph Hellwig <hch at lst.de>; Benjamin Herrenschmidt <benh at kernel.crashing.org>; Paul Mackerras <paulus at samba.org>; Michael Ellerman <mpe at ellerman.id.au>; linuxppc-dev at lists.ozlabs.org; Max Gurtovoy <maxg at mellanox.com>
Subject: Re: [PATCH 1/3] powerpc/powernv: remove the unused pnv_pci_set_p2p function

On Mon, May 06, 2019 at 10:46:11AM +0200, Frederic Barrat wrote:
> Hi,
> The PCI p2p and tunnel code is used by the Mellanox CX5 driver, at 
> least their latest, out of tree version, which is used for CORAL. My 
> understanding is that they'll upstream it at some point, though I 
> don't know what their schedule is like.

FYI, Max who wrote (at least larger parts of) that code is on Cc agreed that all P2P code should go through the kernel P2P infrastructure and might be able to spend some cycles on it.

Which still doesn't change anything about that fact that we [1] generally don't add infrastructure for anything that is not in the tree.

[1] well, powernv seems to have handles this a little oddly, and now is on my special watchlist.

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