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From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
To: Remi Pommarel <repk@triplefau.lt>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	Ellie Reeves <ellierevves@gmail.com>,
	linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] PCI: aardvark: Use LTSSM state to build link training flag
Date: Wed, 25 Sep 2019 14:32:00 +0200	[thread overview]
Message-ID: <20190925143200.696af4cf@windsurf> (raw)
In-Reply-To: <20190522213351.21366-3-repk@triplefau.lt>

Hello Remi,

On Wed, 22 May 2019 23:33:51 +0200
Remi Pommarel <repk@triplefau.lt> wrote:

> Aardvark's PCI_EXP_LNKSTA_LT flag in its link status register is not
> implemented and does not reflect the actual link training state (the
> flag is always set to 0). In order to support link re-training feature
> this flag has to be emulated. The Link Training and Status State
> Machine (LTSSM) flag in Aardvark LMI config register could be used as
> a link training indicator. Indeed if the LTSSM is in L0 or upper state
> then link training has completed (see [1]).
> 
> Unfortunately because after asking a link retraining it takes a while
> for the LTSSM state to become less than 0x10 (due to L0s to recovery
> state transition delays), LTSSM can still be in L0 while link training
> has not finished yet. So this waits for link to be in recovery or lesser
> state before returning after asking for a link retrain.
> 
> [1] "PCI Express Base Specification", REV. 4.0
>     PCI Express, February 19 2014, Table 4-14
> 
> Signed-off-by: Remi Pommarel <repk@triplefau.lt>

Here as well, sorry for the very long delay, and many thanks for the
great research work, including the arm-trusted-firmware fix. I reviewed
the implementation, and tested on my Armada 3720 DB board with a E1000E
NIC, and it all looks good to me.

Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

WARNING: multiple messages have this Message-ID (diff)
From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
To: Remi Pommarel <repk@triplefau.lt>
Cc: Ellie Reeves <ellierevves@gmail.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	Bjorn Helgaas <helgaas@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3] PCI: aardvark: Use LTSSM state to build link training flag
Date: Wed, 25 Sep 2019 14:32:00 +0200	[thread overview]
Message-ID: <20190925143200.696af4cf@windsurf> (raw)
In-Reply-To: <20190522213351.21366-3-repk@triplefau.lt>

Hello Remi,

On Wed, 22 May 2019 23:33:51 +0200
Remi Pommarel <repk@triplefau.lt> wrote:

> Aardvark's PCI_EXP_LNKSTA_LT flag in its link status register is not
> implemented and does not reflect the actual link training state (the
> flag is always set to 0). In order to support link re-training feature
> this flag has to be emulated. The Link Training and Status State
> Machine (LTSSM) flag in Aardvark LMI config register could be used as
> a link training indicator. Indeed if the LTSSM is in L0 or upper state
> then link training has completed (see [1]).
> 
> Unfortunately because after asking a link retraining it takes a while
> for the LTSSM state to become less than 0x10 (due to L0s to recovery
> state transition delays), LTSSM can still be in L0 while link training
> has not finished yet. So this waits for link to be in recovery or lesser
> state before returning after asking for a link retrain.
> 
> [1] "PCI Express Base Specification", REV. 4.0
>     PCI Express, February 19 2014, Table 4-14
> 
> Signed-off-by: Remi Pommarel <repk@triplefau.lt>

Here as well, sorry for the very long delay, and many thanks for the
great research work, including the arm-trusted-firmware fix. I reviewed
the implementation, and tested on my Armada 3720 DB board with a E1000E
NIC, and it all looks good to me.

Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-09-25 12:32 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 21:33 [PATCH v3] PCI: aardvark: Use LTSSM state to build link training flag Remi Pommarel
2019-05-22 21:33 ` Remi Pommarel
2019-08-06 18:50 ` Remi Pommarel
2019-08-06 18:50   ` Remi Pommarel
2019-09-25 12:32 ` Thomas Petazzoni [this message]
2019-09-25 12:32   ` Thomas Petazzoni
2019-09-30 15:40 ` Andrew Murray
2019-09-30 15:40   ` Andrew Murray
2019-09-30 16:52   ` Remi Pommarel
2019-09-30 16:52     ` Remi Pommarel
2019-10-01  8:05     ` Andrew Murray
2019-10-01  8:05       ` Andrew Murray
2019-10-13 10:34       ` Marc Zyngier
2019-10-13 10:34         ` Marc Zyngier
2019-10-14 10:01         ` Lorenzo Pieralisi
2019-10-14 10:01           ` Lorenzo Pieralisi
2019-10-14 13:06           ` Remi Pommarel
2019-10-14 13:06             ` Remi Pommarel
2019-10-14 13:45             ` Marc Zyngier
2019-10-14 13:45               ` Marc Zyngier
2019-10-14 14:00               ` Remi Pommarel
2019-10-14 14:00                 ` Remi Pommarel
2019-10-14 14:18                 ` Marc Zyngier
2019-10-14 14:18                   ` Marc Zyngier
2019-10-14 16:50 ` Lorenzo Pieralisi
2019-10-14 16:50   ` Lorenzo Pieralisi

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