netdev - Re: [PATCH net-next] net/mlx4_core: Warn if device doesn't have enough PCI bandwidth

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Date:	Mon, 6 Jan 2014 21:15:55 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Amir Vadai <amirv@...lanox.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	"David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
	"Or Gerlitz" <ogerlitz@...lanox.com>,
	Eyal Perry <eyalpe@...lanox.com>
Subject: Re: [PATCH net-next] net/mlx4_core: Warn if device doesn't have
 enough PCI bandwidth

On Sat, 2014-01-04 at 21:17 +0200, Amir Vadai wrote:
> From: Eyal Perry <eyalpe@...lanox.com>
> 
> Check if the device get enough bandwidth from the entire PCI chain to satisfy
> its capabilities. This patch determines the PCIe device's bandwidth capabilities
> by reading its PCIe Link Capabilities registers and then call the
> pcie_get_minimum_link function to ensure that the adapter is hooked into a slot
> which is capable of providing the necessary bandwidth capabilities.
[...]

This is essentially another duplicate of what ixgbe and i40e are
doing...  (And the out-of-tree version of sfc does it too, but I never
felt that was ready for in-tree.)

We ought to have a generic PCI layer function that warns when a PCIe
device is running below maximum link width/speed.  Maybe even run it as
soon as the device is enumerated, so that a driver doesn't need to do
anything.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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