[PATCH 0/3] i.MX6 PCIe fixes for 3.17

[PATCH 0/3] i.MX6 PCIe fixes for 3.17

[Lucas Stach]

Two important fixes for i.MX6 PCIe that should go in to 3.17

Also I'm adding myself as a co-maintainer of the driver as I'm
already keeping an eye on it and Richard seems to be ok with this.

Lucas Stach (3):
  MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver
  PCI: imx6: prevent driver unbind
  PCI: imx6: fix boot hang when link already enabled

 MAINTAINERS                 |  1 +
 drivers/pci/host/pci-imx6.c | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

-- 
2.0.1

[PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver

[Lucas Stach]

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
I've talked privately to Richard about this and he's
in favor, but still should give an public ACK.
---
 MAINTAINERS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 134483f206e4..54c23c4fcbb0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6775,6 +6775,7 @@ F:	arch/x86/kernel/quirks.c
 PCI DRIVER FOR IMX6
 M:	Richard Zhu <r65037@freescale.com>
 M:	Shawn Guo <shawn.guo@linaro.org>
+M:	Lucas Stach <l.stach@pengutronix.de>
 L:	linux-pci@vger.kernel.org
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
-- 
2.0.1

[PATCH 2/3] PCI: imx6: prevent driver unbind

[Lucas Stach]

The current code is not prepared for the driver to be
bound/unbound arbitrarily.

Prevent possible user visible issues by disabling the
bind sysfs attributes.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
 drivers/pci/host/pci-imx6.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index a568efaa331c..ceb1677884b2 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -600,6 +600,7 @@ static struct platform_driver imx6_pcie_driver = {
 		.name	= "imx6q-pcie",
 		.owner	= THIS_MODULE,
 		.of_match_table = imx6_pcie_of_match,
+		.suppress_bind_attrs = true,
 	},
 };
 
-- 
2.0.1

[PATCH 3/3] PCI: imx6: fix boot hang when link already enabled

[Lucas Stach]

This fixes a boot hang observed when the bootloader
already enabled the PCIe link for it's own use. The
fundamental problem is that Freescale forgot to wire
up the core reset, so software doesn't have a sane way
to get the core into a defined state.

According to the DW PCIe core reference manual configuration
of the core may only happen when the LTSSM is disabled, so
this is one of the first things we need to do. Apparently
this isn't safe to do when the LTSSM is in any other state
than "detect" as we observe an instant machine hang when
trying to do so while the link is already up.

As a workaround force LTSSM into detect state right before
hitting the disable switch.

Reported-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Tim Harvey <tharvey@gateworks.com>
---
v2: - messed up the first submission by omitting a chunk
v3: - check if bootloader actually enabled link before
      touching any core registers
    - add a comment to explain things a bit
    - add shutdown hook to clean state on reboot

Fabios delay workaround worked because of the following
conditions:
1. The driver gets probed and pulls the peripheral reset GPIO
2. Peripheral is held in reset, so won't answer any link
negotiation requests
3. The LTSSM times out and falls back into detect state
after 24ms (that's why a 30ms delay helps)
4. After LTSSM entered detect state it's safe to hit the
disable switch
---
 drivers/pci/host/pci-imx6.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index ceb1677884b2..8199257f7f28 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -49,6 +49,9 @@ struct imx6_pcie {
 
 /* PCIe Port Logic registers (memory-mapped) */
 #define PL_OFFSET 0x700
+#define PCIE_PL_PFLR (PL_OFFSET + 0x08)
+#define PCIE_PL_PFLR_LINK_STATE_MASK		(0x3f << 16)
+#define PCIE_PL_PFLR_FORCE_LINK			(1 << 15)
 #define PCIE_PHY_DEBUG_R0 (PL_OFFSET + 0x28)
 #define PCIE_PHY_DEBUG_R1 (PL_OFFSET + 0x2c)
 #define PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING	(1 << 29)
@@ -214,6 +217,31 @@ static int imx6q_pcie_abort_handler(unsigned long addr,
 static int imx6_pcie_assert_core_reset(struct pcie_port *pp)
 {
 	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
+	u32 val, gpr1, gpr12;
+
+	/*
+	 * If the bootloader already enabled the link we need some special
+	 * handling to get the core back into a state where it is safe to
+	 * touch it for configuration. As there is no dedicated reset signal
+	 * wired up for MX6QDL, we need to manually force LTSSM into "detect"
+	 * state before completely disabling LTSSM, which is a prerequisite
+	 * for core configuration.
+	 * If both LTSSM_ENABLE and REF_SSP_ENABLE are active we have a strong
+	 * indication that the bootloader activated the link.
+	 */
+	regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, &gpr1);
+	regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, &gpr12);
+
+	if ((gpr1 & IMX6Q_GPR1_PCIE_REF_CLK_EN) &&
+	    (gpr12 & IMX6Q_GPR12_PCIE_CTL_2)) {
+		val = readl(pp->dbi_base + PCIE_PL_PFLR);
+		val &= ~PCIE_PL_PFLR_LINK_STATE_MASK;
+		val |= PCIE_PL_PFLR_FORCE_LINK;
+		writel(val, pp->dbi_base + PCIE_PL_PFLR);
+
+		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
+				IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);
+	}
 
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
 			IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
@@ -589,6 +617,14 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static void imx6_pcie_shutdown(struct platform_device *pdev)
+{
+	struct imx6_pcie *imx6_pcie = platform_get_drvdata(pdev);
+
+	/* bring down link, so bootloader gets clean state in case of reboot */
+	imx6_pcie_assert_core_reset(&imx6_pcie->pp);
+}
+
 static const struct of_device_id imx6_pcie_of_match[] = {
 	{ .compatible = "fsl,imx6q-pcie", },
 	{},
@@ -602,6 +638,7 @@ static struct platform_driver imx6_pcie_driver = {
 		.of_match_table = imx6_pcie_of_match,
 		.suppress_bind_attrs = true,
 	},
+	.shutdown = imx6_pcie_shutdown,
 };
 
 /* Freescale PCIe driver does not allow module unload */
-- 
2.0.1

Re: [PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver

[Jingoo Han]

On Thursday, July 24, 2014 2:40 AM, Lucas Stach wrote:
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
> I've talked privately to Richard about this and he's
> in favor, but still should give an public ACK.

OK, I see. I also think that you are the proper person for
maintaining the i.MX6 PCI driver.

Acked-by: Jingoo Han <jg1.han@samsung.com>

However, you still need the ACK from Richard Zhu or Shawn Guo.

Best regards,
Jingoo Han

> ---
>  MAINTAINERS | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 134483f206e4..54c23c4fcbb0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6775,6 +6775,7 @@ F:	arch/x86/kernel/quirks.c
>  PCI DRIVER FOR IMX6
>  M:	Richard Zhu <r65037@freescale.com>
>  M:	Shawn Guo <shawn.guo@linaro.org>
> +M:	Lucas Stach <l.stach@pengutronix.de>
>  L:	linux-pci@vger.kernel.org
>  L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
>  S:	Maintained
> --
> 2.0.1

Re: [PATCH 2/3] PCI: imx6: prevent driver unbind

[Jingoo Han]

On Thursday, July 24, 2014 2:40 AM, Lucas Stach wrote:
> 
> The current code is not prepared for the driver to be
> bound/unbound arbitrarily.
> 
> Prevent possible user visible issues by disabling the
> bind sysfs attributes.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
>  drivers/pci/host/pci-imx6.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index a568efaa331c..ceb1677884b2 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -600,6 +600,7 @@ static struct platform_driver imx6_pcie_driver = {
>  		.name	= "imx6q-pcie",
>  		.owner	= THIS_MODULE,
>  		.of_match_table = imx6_pcie_of_match,
> +		.suppress_bind_attrs = true,

pci-imx6.c already uses platform_driver_probe().
In platform_driver_probe(),suppress_bind_attrs is set as true as below,

./drivers/base/platform.c

int __init_or_module platform_driver_probe(struct platform_driver *drv,
		int (*probe)(struct platform_device *))
{
	int retval, code;

	/*
	 * Prevent driver from requesting probe deferral to avoid further
	 * futile probe attempts.
	 */
	drv->prevent_deferred_probe = true;

	/* make sure driver won't have bind/unbind attributes */
	drv->driver.suppress_bind_attrs = true;

So, it looks duplicated.
Is there any reason to do it twice?

Best regards,
Jingoo Han

>  	},
>  };
> 
> --
> 2.0.1

RE: [PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver

[Hong-Xing.Zhu]

> -----Original Message-----
> From: Lucas Stach [mailto:l.stach@pengutronix.de]
> Sent: Thursday, July 24, 2014 1:40 AM
> To: Bjorn Helgaas
> Cc: linux-pci@vger.kernel.org; Zhu Richard-R65037; Guo Shawn-R65073;
> kernel@pengutronix.de
> Subject: [PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI
> driver
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
> I've talked privately to Richard about this and he's in favor, but still
> should give an public ACK.
[Richard] Acked-by: Richard Zhu <r65037@freescale.com>

Best Regards
Richard Zhu


> ---
>  MAINTAINERS | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 134483f206e4..54c23c4fcbb0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6775,6 +6775,7 @@ F:	arch/x86/kernel/quirks.c
>  PCI DRIVER FOR IMX6
>  M:	Richard Zhu <r65037@freescale.com>
>  M:	Shawn Guo <shawn.guo@linaro.org>
> +M:	Lucas Stach <l.stach@pengutronix.de>
>  L:	linux-pci@vger.kernel.org
>  L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
>  S:	Maintained
> --
> 2.0.1

Re: [PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver

[Shawn Guo]

On Wed, Jul 23, 2014 at 07:40:15PM +0200, Lucas Stach wrote:
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
> I've talked privately to Richard about this and he's
> in favor, but still should give an public ACK.
> ---
>  MAINTAINERS | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 134483f206e4..54c23c4fcbb0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6775,6 +6775,7 @@ F:	arch/x86/kernel/quirks.c
>  PCI DRIVER FOR IMX6
>  M:	Richard Zhu <r65037@freescale.com>
>  M:	Shawn Guo <shawn.guo@linaro.org>
> +M:	Lucas Stach <l.stach@pengutronix.de>

Acked-by: Shawn Guo <shawn.guo@freescale.com>

I would step down from the position, so I prefer you replace myself.

Shawn

>  L:	linux-pci@vger.kernel.org
>  L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
>  S:	Maintained
> -- 
> 2.0.1
> 

Re: [PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver

[Jingoo Han]

On Thursday, July 24, 2014 5:41 PM, Shawn Guo wrote:
> On Wed, Jul 23, 2014 at 07:40:15PM +0200, Lucas Stach wrote:
> > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> > ---
> > I've talked privately to Richard about this and he's
> > in favor, but still should give an public ACK.
> > ---
> >  MAINTAINERS | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 134483f206e4..54c23c4fcbb0 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -6775,6 +6775,7 @@ F:	arch/x86/kernel/quirks.c
> >  PCI DRIVER FOR IMX6
> >  M:	Richard Zhu <r65037@freescale.com>
> >  M:	Shawn Guo <shawn.guo@linaro.org>
> > +M:	Lucas Stach <l.stach@pengutronix.de>
> 
> Acked-by: Shawn Guo <shawn.guo@freescale.com>
> 
> I would step down from the position, so I prefer you replace myself.

Hi Shawn,

OK, I also agree with your suggestion.
Then, do you mean the following? It looks good.

 PCI DRIVER FOR IMX6
 M:	Richard Zhu <r65037@freescale.com>
+M:	Lucas Stach <l.stach@pengutronix.de>
 M:	Shawn Guo <shawn.guo@linaro.org>

Thanks.

Best regards,
Jingoo Han

> 
> Shawn
> 
> >  L:	linux-pci@vger.kernel.org
> >  L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
> >  S:	Maintained
> > --
> > 2.0.1
> >

Re: [PATCH 1/3] MAINTAINERS: add myself as co-maintainer for i.MX6 PCI driver

[Shawn Guo]

On Thu, Jul 24, 2014 at 05:52:06PM +0900, Jingoo Han wrote:
> On Thursday, July 24, 2014 5:41 PM, Shawn Guo wrote:
> > On Wed, Jul 23, 2014 at 07:40:15PM +0200, Lucas Stach wrote:
> > > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> > > ---
> > > I've talked privately to Richard about this and he's
> > > in favor, but still should give an public ACK.
> > > ---
> > >  MAINTAINERS | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 134483f206e4..54c23c4fcbb0 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -6775,6 +6775,7 @@ F:	arch/x86/kernel/quirks.c
> > >  PCI DRIVER FOR IMX6
> > >  M:	Richard Zhu <r65037@freescale.com>
> > >  M:	Shawn Guo <shawn.guo@linaro.org>
> > > +M:	Lucas Stach <l.stach@pengutronix.de>
> > 
> > Acked-by: Shawn Guo <shawn.guo@freescale.com>
> > 
> > I would step down from the position, so I prefer you replace myself.
> 
> Hi Shawn,
> 
> OK, I also agree with your suggestion.
> Then, do you mean the following? It looks good.
> 
>  PCI DRIVER FOR IMX6
>  M:	Richard Zhu <r65037@freescale.com>
> +M:	Lucas Stach <l.stach@pengutronix.de>
>  M:	Shawn Guo <shawn.guo@linaro.org>

Hi Jingoo,

I meant the following :)

  PCI DRIVER FOR IMX6
  M:	Richard Zhu <r65037@freescale.com>
 -M:	Shawn Guo <shawn.guo@linaro.org>
 +M:	Lucas Stach <l.stach@pengutronix.de>

Shawn