diff mbox

[resend] PCI: designware: fix register access before host init

Message ID 20161018082549.10905-1-l.stach@pengutronix.de (mailing list archive)
State New, archived
Delegated to: Bjorn Helgaas
Headers show

Commit Message

Lucas Stach Oct. 18, 2016, 8:25 a.m. UTC 
The function used to determine if iATU unroll is available will read
a RC register. This is not possible and will result in a system hang
if the RC is still in reset, so it is only safe to call this function
after host_init() has been called.

Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature)
Reported-by: Gary Bisson <gary.bisson@boundarydevices.com>
Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
 drivers/pci/host/pcie-designware.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Han Jingoo Oct. 18, 2016, 4:30 p.m. UTC | #1 
On Tuesday, October 18, 2016 4:26 AM, Lucas Stach wrote:
>
> The function used to determine if iATU unroll is available will read a RC
register.
> This is not possible and will result in a system hang if the RC is still
in reset,
>  so it is only safe to call this function after host_init() has been
called.
>
> Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature)
> Reported-by: Gary Bisson <gary.bisson@boundarydevices.com>
> Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

It looks good!

Acked-by: Jingoo Han <jigoohan1@gmail.com>


> ---
>  drivers/pci/host/pcie-designware.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/host/pcie-designware.c
b/drivers/pci/host/pcie-designware.c
> index 035f50c03281..74510508fafc 100644
> --- a/drivers/pci/host/pcie-designware.c
> +++ b/drivers/pci/host/pcie-designware.c
> @@ -637,11 +637,11 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  		}
>  	}
>  
> -	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
> -
>  	if (pp->ops->host_init)
>  		pp->ops->host_init(pp);
>  
> +	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
> +
>  	pp->root_bus_nr = pp->busn->start;
>  	if (IS_ENABLED(CONFIG_PCI_MSI)) {
>  		bus = pci_scan_root_bus_msi(pp->dev, pp->root_bus_nr,
> --
> 2.9.3


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Fabio Estevam Oct. 18, 2016, 6:36 p.m. UTC | #2 
On Tue, Oct 18, 2016 at 6:25 AM, Lucas Stach <l.stach@pengutronix.de> wrote:
> The function used to determine if iATU unroll is available will read
> a RC register. This is not possible and will result in a system hang
> if the RC is still in reset, so it is only safe to call this function
> after host_init() has been called.
>
> Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature)
> Reported-by: Gary Bisson <gary.bisson@boundarydevices.com>
> Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

This fixes the hang on mx6, thanks:

Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
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Bjorn Helgaas Oct. 21, 2016, 3:31 p.m. UTC | #3 
On Tue, Oct 18, 2016 at 10:25:49AM +0200, Lucas Stach wrote:
> The function used to determine if iATU unroll is available will read
> a RC register. This is not possible and will result in a system hang
> if the RC is still in reset, so it is only safe to call this function
> after host_init() has been called.

I'm sure Joao tested a0601a470537 somewhere, so I assume this hang only
happens on certain systems?

I'm wondering if this is suggesting something that's currently done
differently across the drivers but could be done more similarly.

> Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature)
> Reported-by: Gary Bisson <gary.bisson@boundarydevices.com>
> Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
>  drivers/pci/host/pcie-designware.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
> index 035f50c03281..74510508fafc 100644
> --- a/drivers/pci/host/pcie-designware.c
> +++ b/drivers/pci/host/pcie-designware.c
> @@ -637,11 +637,11 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  		}
>  	}
>  
> -	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
> -
>  	if (pp->ops->host_init)
>  		pp->ops->host_init(pp);
>  
> +	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
> +
>  	pp->root_bus_nr = pp->busn->start;
>  	if (IS_ENABLED(CONFIG_PCI_MSI)) {
>  		bus = pci_scan_root_bus_msi(pp->dev, pp->root_bus_nr,
> -- 
> 2.9.3
> 
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Bjorn Helgaas Oct. 21, 2016, 4:22 p.m. UTC | #4 
[+cc Joao, Niklas, Carlos, Jose, Jesper]

On Fri, Oct 21, 2016 at 10:31:42AM -0500, Bjorn Helgaas wrote:
> On Tue, Oct 18, 2016 at 10:25:49AM +0200, Lucas Stach wrote:
> > The function used to determine if iATU unroll is available will read
> > a RC register. This is not possible and will result in a system hang
> > if the RC is still in reset, so it is only safe to call this function
> > after host_init() has been called.
> 
> I'm sure Joao tested a0601a470537 somewhere, so I assume this hang only
> happens on certain systems?
> 
> I'm wondering if this is suggesting something that's currently done
> differently across the drivers but could be done more similarly.
> 
> > Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature)
> > Reported-by: Gary Bisson <gary.bisson@boundarydevices.com>
> > Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>
> > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> > ---
> >  drivers/pci/host/pcie-designware.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
> > index 035f50c03281..74510508fafc 100644
> > --- a/drivers/pci/host/pcie-designware.c
> > +++ b/drivers/pci/host/pcie-designware.c
> > @@ -637,11 +637,11 @@ int dw_pcie_host_init(struct pcie_port *pp)
> >  		}
> >  	}
> >  
> > -	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
> > -
> >  	if (pp->ops->host_init)
> >  		pp->ops->host_init(pp);
> >  
> > +	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
> > +

Niklas suggested this exact change earlier [1], but Joao pointed out the
problem with calling dw_pcie_iatu_unroll_enabled() after calling
pp->ops->host_init():

  dw_pcie_host_init
    pp->ops->host_init
      dw_pcie_setup_rc
        dw_pcie_prog_outbound_atu
          if (pp->iatu_unroll_enabled)
	    ...
    pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled()

We check iatu_unroll_enabled in dw_pcie_prog_outbound_atu() before it
has been set.

Niklas' second patch [2] looks like a better fix.  Can you guys take a
look and see if you agree?

[1] http://lkml.kernel.org/r/b53d5807-8199-5789-6184-e37324a1d79e@axis.com
[2] http://lkml.kernel.org/r/1476482095-26289-1-git-send-email-niklass@axis.com

> >  	pp->root_bus_nr = pp->busn->start;
> >  	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> >  		bus = pci_scan_root_bus_msi(pp->dev, pp->root_bus_nr,
> > -- 
> > 2.9.3
> > 
> > --
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João Pinto Oct. 21, 2016, 4:44 p.m. UTC | #5 
Hi,
Sorry for replying directly from gmail, I don't have the Linux
environment ready yet :)
Niklas patch is the one that should be applied, because in the
host_init  we need to know if the iATU is in Unroll or in Legacy mode.

Thanks.

2016-10-21 17:22 GMT+01:00 Bjorn Helgaas <helgaas@kernel.org>:
> [+cc Joao, Niklas, Carlos, Jose, Jesper]
>
> On Fri, Oct 21, 2016 at 10:31:42AM -0500, Bjorn Helgaas wrote:
>> On Tue, Oct 18, 2016 at 10:25:49AM +0200, Lucas Stach wrote:
>> > The function used to determine if iATU unroll is available will read
>> > a RC register. This is not possible and will result in a system hang
>> > if the RC is still in reset, so it is only safe to call this function
>> > after host_init() has been called.
>>
>> I'm sure Joao tested a0601a470537 somewhere, so I assume this hang only
>> happens on certain systems?
>>
>> I'm wondering if this is suggesting something that's currently done
>> differently across the drivers but could be done more similarly.
>>
>> > Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature)
>> > Reported-by: Gary Bisson <gary.bisson@boundarydevices.com>
>> > Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>
>> > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
>> > ---
>> >  drivers/pci/host/pcie-designware.c | 4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
>> > index 035f50c03281..74510508fafc 100644
>> > --- a/drivers/pci/host/pcie-designware.c
>> > +++ b/drivers/pci/host/pcie-designware.c
>> > @@ -637,11 +637,11 @@ int dw_pcie_host_init(struct pcie_port *pp)
>> >             }
>> >     }
>> >
>> > -   pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
>> > -
>> >     if (pp->ops->host_init)
>> >             pp->ops->host_init(pp);
>> >
>> > +   pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
>> > +
>
> Niklas suggested this exact change earlier [1], but Joao pointed out the
> problem with calling dw_pcie_iatu_unroll_enabled() after calling
> pp->ops->host_init():
>
>   dw_pcie_host_init
>     pp->ops->host_init
>       dw_pcie_setup_rc
>         dw_pcie_prog_outbound_atu
>           if (pp->iatu_unroll_enabled)
>             ...
>     pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled()
>
> We check iatu_unroll_enabled in dw_pcie_prog_outbound_atu() before it
> has been set.
>
> Niklas' second patch [2] looks like a better fix.  Can you guys take a
> look and see if you agree?
>
> [1] http://lkml.kernel.org/r/b53d5807-8199-5789-6184-e37324a1d79e@axis.com
> [2] http://lkml.kernel.org/r/1476482095-26289-1-git-send-email-niklass@axis.com
>
>> >     pp->root_bus_nr = pp->busn->start;
>> >     if (IS_ENABLED(CONFIG_PCI_MSI)) {
>> >             bus = pci_scan_root_bus_msi(pp->dev, pp->root_bus_nr,
>> > --
>> > 2.9.3
>> >
>> > --
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>> > the body of a message to majordomo@vger.kernel.org
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diff mbox

Patch

diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index 035f50c03281..74510508fafc 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -637,11 +637,11 @@  int dw_pcie_host_init(struct pcie_port *pp)
 		}
 	}
 
-	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
-
 	if (pp->ops->host_init)
 		pp->ops->host_init(pp);
 
+	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
+
 	pp->root_bus_nr = pp->busn->start;
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		bus = pci_scan_root_bus_msi(pp->dev, pp->root_bus_nr,