diff mbox

PCI: imx6: Fix link_up detection

Message ID 52FD0F1A.4000208@boundarydevices.com
State Superseded
Headers show

Commit Message

Troy Kisky Feb. 13, 2014, 6:29 p.m. UTC 
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(-)

Comments

Marek Vasut Feb. 13, 2014, 6:41 p.m. UTC | #1 
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
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Sascha Hauer Feb. 14, 2014, 6:41 a.m. UTC | #2 
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
> 
> 
>
Troy Kisky Feb. 14, 2014, 7:25 p.m. UTC | #3 
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


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Bjorn Helgaas Feb. 18, 2014, 9:15 p.m. UTC | #4 
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
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Sascha Hauer Feb. 19, 2014, 8:20 a.m. UTC | #5 
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
Shawn Guo Feb. 19, 2014, 8:27 a.m. UTC | #6 
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>

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diff mbox

Patch

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);