[PATCH] PCI: imx6: Fix link_up detection

[PATCH] PCI: imx6: Fix link_up detection

[Sascha Hauer]

This is broken since:

| commit e6daf4a5e1b813bc7f85507ec83b8c2452c121e6
| Author: Marek Vasut <marex@denx.de>
| Date:   Thu Dec 12 22:49:59 2013 +0100
|
|     PCI: imx6: Report "link up" only after link training completes
|
|     While waiting for the PHY to report the PCIe link is up, we might hit a
|     situation where the link training is still in progress, while the PHY
|     already reports the link is up.  Add additional check for this condition.
|
|     Signed-off-by: Marek Vasut <marex@denx.de>
|     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
|     Acked-by: Shawn Guo <shawn.guo@linaro.org>

The problem is: Before the above commit only the PCIE_PHY_DEBUG_R1_XMLH_LINK_UP
bit was used to determine whether the link is up or not. Since the above commit
also the PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING is used. This means a link
still being trained is as link down.
The designware driver changes the PORT_LOGIC_SPEED_CHANGE bit in
dw_pcie_host_init() which causes the link to be retrained. During the next call
to dw_pcie_rd_conf() the link is then reported being down and the function
returns PCIBIOS_DEVICE_NOT_FOUND resulting in nonfunctioning PCIe.

This patch fixes this by waiting until the link training has finished before
testing the PCIE_PHY_DEBUG_R1_XMLH_LINK_UP bit. This is hardly the correct
solution, but I don't know what should be done instead.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Richard Zhu <r65037@freescale.com> (maintainer:PCI DRIVER FOR IMX6)
Cc: Shawn Guo <shawn.guo@linaro.org> (maintainer:PCI DRIVER FOR IMX6)
Cc: Bjorn Helgaas <bhelgaas@google.com> (supporter:PCI SUBSYSTEM)
Cc: linux-pci@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: Marek Vasut <marex@denx.de>
---
 drivers/pci/host/pci-imx6.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index 866bdc7..9b6b501 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -449,6 +449,7 @@ static void imx6_pcie_reset_phy(struct pcie_port *pp)
 static int imx6_pcie_link_up(struct pcie_port *pp)
 {
 	u32 rc, ltssm, rx_valid;
+	int count = 1000;
 
 	/*
 	 * Test if the PHY reports that the link is up and also that
@@ -458,8 +459,13 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
 	 * as well here.
 	 */
 	rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
-	if ((rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP) &&
-	    !(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
+	while (rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING) {
+		if (!count--)
+			return 0;
+		rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
+	}
+
+	if (rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP)
 		return 1;
 
 	/*
-- 
1.8.5.3

Re: [PATCH] PCI: imx6: Fix link_up detection

[Marek Vasut]

On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:

+CC Troy Kisky, since I think he submitted something similar some time ago 
already.

Otherwise I agree this happens.

> This is broken since:
> | commit e6daf4a5e1b813bc7f85507ec83b8c2452c121e6
> | Author: Marek Vasut <marex@denx.de>
> | Date:   Thu Dec 12 22:49:59 2013 +0100
> | 
> |     PCI: imx6: Report "link up" only after link training completes
> |     
> |     While waiting for the PHY to report the PCIe link is up, we might hit
> |     a situation where the link training is still in progress, while the
> |     PHY already reports the link is up.  Add additional check for this
> |     condition.
> |     
> |     Signed-off-by: Marek Vasut <marex@denx.de>
> |     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> |     Acked-by: Shawn Guo <shawn.guo@linaro.org>
> 
> The problem is: Before the above commit only the
> PCIE_PHY_DEBUG_R1_XMLH_LINK_UP bit was used to determine whether the link
> is up or not. Since the above commit also the
> PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING is used. This means a link still
> being trained is as link down.
> The designware driver changes the PORT_LOGIC_SPEED_CHANGE bit in
> dw_pcie_host_init() which causes the link to be retrained. During the next
> call to dw_pcie_rd_conf() the link is then reported being down and the
> function returns PCIBIOS_DEVICE_NOT_FOUND resulting in nonfunctioning
> PCIe.
> 
> This patch fixes this by waiting until the link training has finished
> before testing the PCIE_PHY_DEBUG_R1_XMLH_LINK_UP bit. This is hardly the
> correct solution, but I don't know what should be done instead.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Richard Zhu <r65037@freescale.com> (maintainer:PCI DRIVER FOR IMX6)
> Cc: Shawn Guo <shawn.guo@linaro.org> (maintainer:PCI DRIVER FOR IMX6)
> Cc: Bjorn Helgaas <bhelgaas@google.com> (supporter:PCI SUBSYSTEM)
> Cc: linux-pci@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: Marek Vasut <marex@denx.de>
> ---
>  drivers/pci/host/pci-imx6.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index 866bdc7..9b6b501 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -449,6 +449,7 @@ static void imx6_pcie_reset_phy(struct pcie_port *pp)
>  static int imx6_pcie_link_up(struct pcie_port *pp)
>  {
>  	u32 rc, ltssm, rx_valid;
> +	int count = 1000;
> 
>  	/*
>  	 * Test if the PHY reports that the link is up and also that
> @@ -458,8 +459,13 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
>  	 * as well here.
>  	 */
>  	rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> -	if ((rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP) &&
> -	    !(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
> +	while (rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING) {
> +		if (!count--)
> +			return 0;
> +		rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> +	}
> +
> +	if (rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP)
>  		return 1;
> 
>  	/*

Re: [PATCH] PCI: imx6: Fix link_up detection

[Troy Kisky]

On 2/12/2014 12:36 AM, Marek Vasut wrote:
> On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
>
> +CC Troy Kisky, since I think he submitted something similar some time ago
> already.
>
> Otherwise I agree this happens.
>
Sorry, I haven't submitted this yet, but was planning to today. Here's
what would have been sent.

 From 32c560d33fe2c3945d69f3396689f0abb76f7e1f Mon Sep 17 00:00:00 2001
From: Marek Vasut <marex@denx.de>
Date: Sat, 25 Jan 2014 14:22:48 -0700
Subject: [PATCH 1/1] pci-imx6.c: wait for retraining

This patch handles the case where the PCIe link is up and running, yet drops
into the LTSSM training mode. The link spends short time in the LTSSM training
mode, but the current code can misinterpret it as the link being stalled.
Waiting for the LTSSM training to complete fixes the issue.

Signed-off-by: Marek Vasut <marex@denx.de>
Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>
---
  drivers/pci/host/pci-imx6.c | 47 ++++++++++++++++++++++++++++++++-------------
  1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index e8663a8..ee08250 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -424,20 +424,40 @@ static void imx6_pcie_reset_phy(struct pcie_port *pp)
  
  static int imx6_pcie_link_up(struct pcie_port *pp)
  {
-	u32 rc, ltssm, rx_valid;
+	u32 rc, debug_r0, rx_valid;
+	int count = 5;
  
  	/*
-	 * Test if the PHY reports that the link is up and also that
-	 * the link training finished.  It might happen that the PHY
-	 * reports the link is already up, but the link training bit
-	 * is still set, so make sure to check the training is done
-	 * as well here.
+	 * Test if the PHY reports that the link is up and also that the LTSSM
+	 * training finished. There are three possible states of the link when
+	 * this code is called:
+	 * 1) The link is DOWN (unlikely)
+	 *     The link didn't come up yet for some reason. This usually means
+	 *     we have a real problem somewhere. Reset the PHY and exit. This
+	 *     state calls for inspection of the DEBUG registers.
+	 * 2) The link is UP, but still in LTSSM training
+	 *     Wait for the training to finish, which should take a very short
+	 *     time. If the training does not finish, we have a problem and we
+	 *     need to inspect the DEBUG registers. If the training does finish,
+	 *     the link is up and operating correctly.
+	 * 3) The link is UP and no longer in LTSSM training
+	 *     The link is up and operating correctly.
  	 */
-	rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
-	if ((rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP) &&
-	    !(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
-		return 1;
-
+	while (1) {
+		rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
+		if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP))
+			break;
+		if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
+			return 1;
+		if (!count--)
+			break;
+		dev_dbg(pp->dev, "Link is up, but still in training\n");
+		/*
+		 * Wait a little bit, then re-check if the link finished
+		 * the training.
+		 */
+		usleep_range(1000, 2000);
+	}
  	/*
  	 * From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
  	 * Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2).
@@ -446,15 +466,16 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
  	 * to gen2 is stuck
  	 */
  	pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid);
-	ltssm = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0) & 0x3F;
+	debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0);
  
  	if (rx_valid & 0x01)
  		return 0;
  
-	if (ltssm != 0x0d)
+	if ((debug_r0 & 0x3f) != 0x0d)
  		return 0;
  
  	dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n");
+	dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc);
  
  	imx6_pcie_reset_phy(pp);
  
-- 
1.8.1.2

Re: [PATCH] PCI: imx6: Fix link_up detection

[Marek Vasut]

On Thursday, February 13, 2014 at 07:29:46 PM, Troy Kisky wrote:
> On 2/12/2014 12:36 AM, Marek Vasut wrote:
> > On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
> > 
> > +CC Troy Kisky, since I think he submitted something similar some time
> > ago already.
> > 
> > Otherwise I agree this happens.
> 
> Sorry, I haven't submitted this yet, but was planning to today. Here's
> what would have been sent.

Release early, release often ... ;-)

Best regards,
Marek Vasut

Re: [PATCH] PCI: imx6: Fix link_up detection

[Sascha Hauer]

On Thu, Feb 13, 2014 at 11:29:46AM -0700, Troy Kisky wrote:
> On 2/12/2014 12:36 AM, Marek Vasut wrote:
> >On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
> >
> >+CC Troy Kisky, since I think he submitted something similar some time ago
> >already.
> >
> >Otherwise I agree this happens.
> >
> Sorry, I haven't submitted this yet, but was planning to today. Here's
> what would have been sent.
> 
> From 32c560d33fe2c3945d69f3396689f0abb76f7e1f Mon Sep 17 00:00:00 2001
> From: Marek Vasut <marex@denx.de>
> Date: Sat, 25 Jan 2014 14:22:48 -0700
> Subject: [PATCH 1/1] pci-imx6.c: wait for retraining
> 
> This patch handles the case where the PCIe link is up and running, yet drops
> into the LTSSM training mode. The link spends short time in the LTSSM training
> mode, but the current code can misinterpret it as the link being stalled.
> Waiting for the LTSSM training to complete fixes the issue.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>

Thanks, that works.

Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

Sascha

> ---
>  drivers/pci/host/pci-imx6.c | 47 ++++++++++++++++++++++++++++++++-------------
>  1 file changed, 34 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index e8663a8..ee08250 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -424,20 +424,40 @@ static void imx6_pcie_reset_phy(struct pcie_port *pp)
>  static int imx6_pcie_link_up(struct pcie_port *pp)
>  {
> -	u32 rc, ltssm, rx_valid;
> +	u32 rc, debug_r0, rx_valid;
> +	int count = 5;
>  	/*
> -	 * Test if the PHY reports that the link is up and also that
> -	 * the link training finished.  It might happen that the PHY
> -	 * reports the link is already up, but the link training bit
> -	 * is still set, so make sure to check the training is done
> -	 * as well here.
> +	 * Test if the PHY reports that the link is up and also that the LTSSM
> +	 * training finished. There are three possible states of the link when
> +	 * this code is called:
> +	 * 1) The link is DOWN (unlikely)
> +	 *     The link didn't come up yet for some reason. This usually means
> +	 *     we have a real problem somewhere. Reset the PHY and exit. This
> +	 *     state calls for inspection of the DEBUG registers.
> +	 * 2) The link is UP, but still in LTSSM training
> +	 *     Wait for the training to finish, which should take a very short
> +	 *     time. If the training does not finish, we have a problem and we
> +	 *     need to inspect the DEBUG registers. If the training does finish,
> +	 *     the link is up and operating correctly.
> +	 * 3) The link is UP and no longer in LTSSM training
> +	 *     The link is up and operating correctly.
>  	 */
> -	rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> -	if ((rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP) &&
> -	    !(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
> -		return 1;
> -
> +	while (1) {
> +		rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> +		if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP))
> +			break;
> +		if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
> +			return 1;
> +		if (!count--)
> +			break;
> +		dev_dbg(pp->dev, "Link is up, but still in training\n");
> +		/*
> +		 * Wait a little bit, then re-check if the link finished
> +		 * the training.
> +		 */
> +		usleep_range(1000, 2000);
> +	}
>  	/*
>  	 * From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
>  	 * Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2).
> @@ -446,15 +466,16 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
>  	 * to gen2 is stuck
>  	 */
>  	pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid);
> -	ltssm = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0) & 0x3F;
> +	debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0);
>  	if (rx_valid & 0x01)
>  		return 0;
> -	if (ltssm != 0x0d)
> +	if ((debug_r0 & 0x3f) != 0x0d)
>  		return 0;
>  	dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n");
> +	dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc);
>  	imx6_pcie_reset_phy(pp);
> -- 
> 1.8.1.2
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH] PCI: imx6: Fix link_up detection

[Troy Kisky]

On 2/13/2014 11:41 PM, Sascha Hauer wrote:
> On Thu, Feb 13, 2014 at 11:29:46AM -0700, Troy Kisky wrote:
>> On 2/12/2014 12:36 AM, Marek Vasut wrote:
>>> On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
>>>
>>> +CC Troy Kisky, since I think he submitted something similar some time ago
>>> already.
>>>
>>> Otherwise I agree this happens.
>>>
>> Sorry, I haven't submitted this yet, but was planning to today. Here's
>> what would have been sent.
>>
>> From 32c560d33fe2c3945d69f3396689f0abb76f7e1f Mon Sep 17 00:00:00 2001
>> From: Marek Vasut <marex@denx.de>
>> Date: Sat, 25 Jan 2014 14:22:48 -0700
>> Subject: [PATCH 1/1] pci-imx6.c: wait for retraining
>>
>> This patch handles the case where the PCIe link is up and running, yet drops
>> into the LTSSM training mode. The link spends short time in the LTSSM training
>> mode, but the current code can misinterpret it as the link being stalled.
>> Waiting for the LTSSM training to complete fixes the issue.
>>
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>
> 
> Thanks, that works.
> 
> Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
> 
> Sascha

I don't want to step on your toes, does that means you
expect me to send a formal patch ?


Thanks
Troy

Re: [PATCH] PCI: imx6: Fix link_up detection

[Bjorn Helgaas]

On Fri, Feb 14, 2014 at 12:25:27PM -0700, Troy Kisky wrote:
> On 2/13/2014 11:41 PM, Sascha Hauer wrote:
> > On Thu, Feb 13, 2014 at 11:29:46AM -0700, Troy Kisky wrote:
> >> On 2/12/2014 12:36 AM, Marek Vasut wrote:
> >>> On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
> >>>
> >>> +CC Troy Kisky, since I think he submitted something similar some time ago
> >>> already.
> >>>
> >>> Otherwise I agree this happens.
> >>>
> >> Sorry, I haven't submitted this yet, but was planning to today. Here's
> >> what would have been sent.
> >>
> >> From 32c560d33fe2c3945d69f3396689f0abb76f7e1f Mon Sep 17 00:00:00 2001
> >> From: Marek Vasut <marex@denx.de>
> >> Date: Sat, 25 Jan 2014 14:22:48 -0700
> >> Subject: [PATCH 1/1] pci-imx6.c: wait for retraining
> >>
> >> This patch handles the case where the PCIe link is up and running, yet drops
> >> into the LTSSM training mode. The link spends short time in the LTSSM training
> >> mode, but the current code can misinterpret it as the link being stalled.
> >> Waiting for the LTSSM training to complete fixes the issue.
> >>
> >> Signed-off-by: Marek Vasut <marex@denx.de>
> >> Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>
> > 
> > Thanks, that works.
> > 
> > Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
> > 
> > Sascha
> 
> I don't want to step on your toes, does that means you
> expect me to send a formal patch ?

I don't care which way we go, but we should make progress on this.

It looks like Troy's patch is slightly more extensive (adds comments, uses
actual times instead of a CPU speed-dependent wait loop, prints registers
for analysis in failure case), so based on that, I would go that route.

But we need an ack from Richard or Shawn anyway, so I'll just wait for
direction from them.

Bjorn

Re: [PATCH] PCI: imx6: Fix link_up detection

[Sascha Hauer]

On Fri, Feb 14, 2014 at 12:25:27PM -0700, Troy Kisky wrote:
> On 2/13/2014 11:41 PM, Sascha Hauer wrote:
> > On Thu, Feb 13, 2014 at 11:29:46AM -0700, Troy Kisky wrote:
> >> On 2/12/2014 12:36 AM, Marek Vasut wrote:
> >>> On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
> >>>
> >>> +CC Troy Kisky, since I think he submitted something similar some time ago
> >>> already.
> >>>
> >>> Otherwise I agree this happens.
> >>>
> >> Sorry, I haven't submitted this yet, but was planning to today. Here's
> >> what would have been sent.
> >>
> >> From 32c560d33fe2c3945d69f3396689f0abb76f7e1f Mon Sep 17 00:00:00 2001
> >> From: Marek Vasut <marex@denx.de>
> >> Date: Sat, 25 Jan 2014 14:22:48 -0700
> >> Subject: [PATCH 1/1] pci-imx6.c: wait for retraining
> >>
> >> This patch handles the case where the PCIe link is up and running, yet drops
> >> into the LTSSM training mode. The link spends short time in the LTSSM training
> >> mode, but the current code can misinterpret it as the link being stalled.
> >> Waiting for the LTSSM training to complete fixes the issue.
> >>
> >> Signed-off-by: Marek Vasut <marex@denx.de>
> >> Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>
> > 
> > Thanks, that works.
> > 
> > Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
> > 
> > Sascha
> 
> I don't want to step on your toes, does that means you
> expect me to send a formal patch ?

The patch you sent is formal enough for me, but I won't be the one
applying it. I just wanted to say that I have tested it. I prefer your
patch over mine and I'd like to see it applied.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH] PCI: imx6: Fix link_up detection

[Shawn Guo]

On Fri, Feb 14, 2014 at 07:41:53AM +0100, Sascha Hauer wrote:
> On Thu, Feb 13, 2014 at 11:29:46AM -0700, Troy Kisky wrote:
> > On 2/12/2014 12:36 AM, Marek Vasut wrote:
> > >On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
> > >
> > >+CC Troy Kisky, since I think he submitted something similar some time ago
> > >already.
> > >
> > >Otherwise I agree this happens.
> > >
> > Sorry, I haven't submitted this yet, but was planning to today. Here's
> > what would have been sent.
> > 
> > From 32c560d33fe2c3945d69f3396689f0abb76f7e1f Mon Sep 17 00:00:00 2001
> > From: Marek Vasut <marex@denx.de>
> > Date: Sat, 25 Jan 2014 14:22:48 -0700
> > Subject: [PATCH 1/1] pci-imx6.c: wait for retraining
> > 
> > This patch handles the case where the PCIe link is up and running, yet drops
> > into the LTSSM training mode. The link spends short time in the LTSSM training
> > mode, but the current code can misinterpret it as the link being stalled.
> > Waiting for the LTSSM training to complete fixes the issue.
> > 
> > Signed-off-by: Marek Vasut <marex@denx.de>
> > Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>
> 
> Thanks, that works.
> 
> Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

Acked-by: Shawn Guo <shawn.guo@linaro.org>