netdev - Re: [PATCH 1/5] e1000e: reset MAC-PHY interconnect on 82577/82578

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Date:	Tue, 16 Dec 2014 04:12:06 -0800
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	Zhu Yanjun <zyjzyj2000@...il.com>, stable <stable@...r.kernel.org>,
	Willy Tarreau <w@....eu>
Cc:	netdev@...r.kernel.org, w@....eu,
	Zhu Yanjun <Yanjun.Zhu@...driver.com>,
	Bruce Allan <bruce.w.allan@...el.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH 1/5] e1000e: reset MAC-PHY interconnect on 82577/82578

On Tue, 2014-12-16 at 18:28 +0800, Zhu Yanjun wrote:
> 2.6.x kernels require a similar logic change as commit 6dfaa76 
> [e1000e: reset MAC-PHY interconnect on 82577/82578] introduces
> for newer kernels.
> 
> During Sx->S0 transitions, the interconnect between the MAC and PHY on
> 82577/82578 can remain in SMBus mode instead of transitioning to the
> PCIe-like mode required during normal operation.  Toggling the
> LANPHYPC
> Value bit essentially resets the interconnect forcing it to the
> correct
> mode.
> 
> after review of all intel drivers, found several instances where
> drivers had the incorrect pattern of:
> memory mapped write();
> delay();
> 
> which should always be:
> memory mapped write();
> write flush(); /* aka memory mapped read */
> delay();
> 
> explanation:
> The reason for including the flush is that writes can be held
> (posted) in PCI/PCIe bridges, but the read always has to complete
> synchronously and therefore has to flush all pending writes to a
> device.  If a write is held and followed by a delay, the delay
> means nothing because the write may not have reached hardware
> (maybe even not until the next read)
> 
> Signed-off-by: Bruce Allan <bruce.w.allan@...el.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> Signed-off-by: Zhu Yanjun <Yanjun.Zhu@...driver.com>
> ---
>  drivers/net/e1000e/defines.h |  2 ++
>  drivers/net/e1000e/ich8lan.c | 20 ++++++++++++++++++++
>  2 files changed, 22 insertions(+)

To be clear, Zhu is wanting this applied to stable trees (yet did not CC
stable@...r.kernel.org ).

Willy- I am fine with this series being applied to stable.

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