diff mbox series

[v3] PCI: cadence: Retrain Link to work around Gen2 training defect.

Message ID 20200930182105.9752-1-nadeem@cadence.com
State New
Delegated to: Lorenzo Pieralisi
Headers show
Series [v3] PCI: cadence: Retrain Link to work around Gen2 training defect. | expand

Commit Message

Athani Nadeem Ladkhan Sept. 30, 2020, 6:21 p.m. UTC
Cadence controller will not initiate autonomous speed change if strapped
as Gen2. The Retrain Link bit is set as quirk to enable this speed change.

Signed-off-by: Nadeem Athani <nadeem@cadence.com>
---
Changes in v3:
- To set retrain link bit,checking device capability & link status.
- 32bit read in place of 8bit.
- Minor correction in patch comment.
- Change in variable & macro name.
Changes in v2:
- 16bit read in place of 8bit.
 drivers/pci/controller/cadence/pcie-cadence-host.c | 31 ++++++++++++++++++++++
 drivers/pci/controller/cadence/pcie-cadence.h      |  9 ++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

Comments

Kishon Vijay Abraham I Oct. 19, 2020, 5:28 a.m. UTC | #1
Hi Nadeem,

On 30/09/20 11:51 pm, Nadeem Athani wrote:
> Cadence controller will not initiate autonomous speed change if strapped
> as Gen2. The Retrain Link bit is set as quirk to enable this speed change.
> 
> Signed-off-by: Nadeem Athani <nadeem@cadence.com>
> ---
> Changes in v3:
> - To set retrain link bit,checking device capability & link status.
> - 32bit read in place of 8bit.
> - Minor correction in patch comment.
> - Change in variable & macro name.
> Changes in v2:
> - 16bit read in place of 8bit.
>  drivers/pci/controller/cadence/pcie-cadence-host.c | 31 ++++++++++++++++++++++
>  drivers/pci/controller/cadence/pcie-cadence.h      |  9 ++++++-
>  2 files changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 4550e0d469ca..2b2ae4e18032 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -77,6 +77,36 @@ static struct pci_ops cdns_pcie_host_ops = {
>  	.write		= pci_generic_config_write,
>  };
>  
> +static void cdns_pcie_retrain(struct cdns_pcie *pcie)
> +{
> +	u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
> +	u16 lnk_stat, lnk_ctl;
> +
> +	if (!cdns_pcie_link_up(pcie))
> +		return;
> +

Is there a IP version that can be used to check if that quirk is applicable?
> +	/*
> +	 * Set retrain bit if current speed is 2.5 GB/s,
> +	 * but the PCIe root port support is > 2.5 GB/s.
> +	 */
> +
> +	lnk_cap_sls = cdns_pcie_readl(pcie, (CDNS_PCIE_RP_BASE + pcie_cap_off +
> +				      PCI_EXP_LNKCAP));
> +	if ((lnk_cap_sls & PCI_EXP_LNKCAP_SLS) <= PCI_EXP_LNKCAP_SLS_2_5GB)
> +		return;
> +
> +	lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA);
> +	if ((lnk_stat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB) {
> +		lnk_ctl = cdns_pcie_rp_readw(pcie,
> +					     pcie_cap_off + PCI_EXP_LNKCTL);
> +		lnk_ctl |= PCI_EXP_LNKCTL_RL;
> +		cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
> +				    lnk_ctl);
> +
> +		if (!cdns_pcie_link_up(pcie))

Should this rather be a cdns_pcie_host_wait_for_link()?

Thanks
Kishon

> +			return;
> +	}
> +}
>  
>  static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
>  {
> @@ -115,6 +145,7 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
>  	cdns_pcie_rp_writeb(pcie, PCI_CLASS_PROG, 0);
>  	cdns_pcie_rp_writew(pcie, PCI_CLASS_DEVICE, PCI_CLASS_BRIDGE_PCI);
>  
> +	cdns_pcie_retrain(pcie);
>  	return 0;
>  }
>  
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index feed1e3038f4..5f1cf032ae15 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -119,7 +119,7 @@
>   * Root Port Registers (PCI configuration space for the root port function)
>   */
>  #define CDNS_PCIE_RP_BASE	0x00200000
> -
> +#define CDNS_PCIE_RP_CAP_OFFSET 0xc0
>  
>  /*
>   * Address Translation Registers
> @@ -413,6 +413,13 @@ static inline void cdns_pcie_rp_writew(struct cdns_pcie *pcie,
>  	cdns_pcie_write_sz(addr, 0x2, value);
>  }
>  
> +static inline u16 cdns_pcie_rp_readw(struct cdns_pcie *pcie, u32 reg)
> +{
> +	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
> +
> +	return cdns_pcie_read_sz(addr, 0x2);
> +}
> +
>  /* Endpoint Function register access */
>  static inline void cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn,
>  					  u32 reg, u8 value)
>
Athani Nadeem Ladkhan Oct. 19, 2020, 5:18 p.m. UTC | #2
Hi Kishon,

> -----Original Message-----
> From: Kishon Vijay Abraham I <kishon@ti.com>
> Sent: Monday, October 19, 2020 10:59 AM
> To: Athani Nadeem Ladkhan <nadeem@cadence.com>;
> lorenzo.pieralisi@arm.com; robh@kernel.org; bhelgaas@google.com; linux-
> pci@vger.kernel.org; linux-kernel@vger.kernel.org; Tom Joseph
> <tjoseph@cadence.com>
> Cc: Swapnil Kashinath Jakhade <sjakhade@cadence.com>; Milind Parab
> <mparab@cadence.com>
> Subject: Re: [PATCH v3] PCI: cadence: Retrain Link to work around Gen2
> training defect.
> 
> EXTERNAL MAIL
> 
> 
> Hi Nadeem,
> 
> On 30/09/20 11:51 pm, Nadeem Athani wrote:
> > Cadence controller will not initiate autonomous speed change if
> > strapped as Gen2. The Retrain Link bit is set as quirk to enable this speed
> change.
> >
> > Signed-off-by: Nadeem Athani <nadeem@cadence.com>
> > ---
> > Changes in v3:
> > - To set retrain link bit,checking device capability & link status.
> > - 32bit read in place of 8bit.
> > - Minor correction in patch comment.
> > - Change in variable & macro name.
> > Changes in v2:
> > - 16bit read in place of 8bit.
> >  drivers/pci/controller/cadence/pcie-cadence-host.c | 31
> ++++++++++++++++++++++
> >  drivers/pci/controller/cadence/pcie-cadence.h      |  9 ++++++-
> >  2 files changed, 39 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c
> > b/drivers/pci/controller/cadence/pcie-cadence-host.c
> > index 4550e0d469ca..2b2ae4e18032 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> > +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> > @@ -77,6 +77,36 @@ static struct pci_ops cdns_pcie_host_ops = {
> >  	.write		= pci_generic_config_write,
> >  };
> >
> > +static void cdns_pcie_retrain(struct cdns_pcie *pcie) {
> > +	u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
> > +	u16 lnk_stat, lnk_ctl;
> > +
> > +	if (!cdns_pcie_link_up(pcie))
> > +		return;
> > +
> 
> Is there a IP version that can be used to check if that quirk is applicable?
There is no such provision.
> > +	/*
> > +	 * Set retrain bit if current speed is 2.5 GB/s,
> > +	 * but the PCIe root port support is > 2.5 GB/s.
> > +	 */
> > +
> > +	lnk_cap_sls = cdns_pcie_readl(pcie, (CDNS_PCIE_RP_BASE +
> pcie_cap_off +
> > +				      PCI_EXP_LNKCAP));
> > +	if ((lnk_cap_sls & PCI_EXP_LNKCAP_SLS) <=
> PCI_EXP_LNKCAP_SLS_2_5GB)
> > +		return;
> > +
> > +	lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off +
> PCI_EXP_LNKSTA);
> > +	if ((lnk_stat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB)
> {
> > +		lnk_ctl = cdns_pcie_rp_readw(pcie,
> > +					     pcie_cap_off + PCI_EXP_LNKCTL);
> > +		lnk_ctl |= PCI_EXP_LNKCTL_RL;
> > +		cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
> > +				    lnk_ctl);
> > +
> > +		if (!cdns_pcie_link_up(pcie))
> 
> Should this rather be a cdns_pcie_host_wait_for_link()?
The use of this api cdns_pcie_link_up was mentioned in earlier reviews.
The mentioned api cdns_pcie_host_wait_for_link is a wrapper in which there are multiple checks.
If insist, will replace with it.
Thanks,
Nadeem
> 
> Thanks
> Kishon
> 
> > +			return;
> > +	}
> > +}
> >
> >  static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)  {
> > @@ -115,6 +145,7 @@ static int cdns_pcie_host_init_root_port(struct
> cdns_pcie_rc *rc)
> >  	cdns_pcie_rp_writeb(pcie, PCI_CLASS_PROG, 0);
> >  	cdns_pcie_rp_writew(pcie, PCI_CLASS_DEVICE,
> PCI_CLASS_BRIDGE_PCI);
> >
> > +	cdns_pcie_retrain(pcie);
> >  	return 0;
> >  }
> >
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence.h
> > b/drivers/pci/controller/cadence/pcie-cadence.h
> > index feed1e3038f4..5f1cf032ae15 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence.h
> > +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> > @@ -119,7 +119,7 @@
> >   * Root Port Registers (PCI configuration space for the root port function)
> >   */
> >  #define CDNS_PCIE_RP_BASE	0x00200000
> > -
> > +#define CDNS_PCIE_RP_CAP_OFFSET 0xc0
> >
> >  /*
> >   * Address Translation Registers
> > @@ -413,6 +413,13 @@ static inline void cdns_pcie_rp_writew(struct
> cdns_pcie *pcie,
> >  	cdns_pcie_write_sz(addr, 0x2, value);  }
> >
> > +static inline u16 cdns_pcie_rp_readw(struct cdns_pcie *pcie, u32 reg)
> > +{
> > +	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
> > +
> > +	return cdns_pcie_read_sz(addr, 0x2); }
> > +
> >  /* Endpoint Function register access */  static inline void
> > cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn,
> >  					  u32 reg, u8 value)
> >
Kishon Vijay Abraham I Oct. 23, 2020, 6:56 a.m. UTC | #3
Hi Nadeem,

On 19/10/20 10:48 pm, Athani Nadeem Ladkhan wrote:
> Hi Kishon,
> 
>> -----Original Message-----
>> From: Kishon Vijay Abraham I <kishon@ti.com>
>> Sent: Monday, October 19, 2020 10:59 AM
>> To: Athani Nadeem Ladkhan <nadeem@cadence.com>;
>> lorenzo.pieralisi@arm.com; robh@kernel.org; bhelgaas@google.com; linux-
>> pci@vger.kernel.org; linux-kernel@vger.kernel.org; Tom Joseph
>> <tjoseph@cadence.com>
>> Cc: Swapnil Kashinath Jakhade <sjakhade@cadence.com>; Milind Parab
>> <mparab@cadence.com>
>> Subject: Re: [PATCH v3] PCI: cadence: Retrain Link to work around Gen2
>> training defect.
>>
>> EXTERNAL MAIL
>>
>>
>> Hi Nadeem,
>>
>> On 30/09/20 11:51 pm, Nadeem Athani wrote:
>>> Cadence controller will not initiate autonomous speed change if
>>> strapped as Gen2. The Retrain Link bit is set as quirk to enable this speed
>> change.
>>>
>>> Signed-off-by: Nadeem Athani <nadeem@cadence.com>
>>> ---
>>> Changes in v3:
>>> - To set retrain link bit,checking device capability & link status.
>>> - 32bit read in place of 8bit.
>>> - Minor correction in patch comment.
>>> - Change in variable & macro name.
>>> Changes in v2:
>>> - 16bit read in place of 8bit.
>>>  drivers/pci/controller/cadence/pcie-cadence-host.c | 31
>> ++++++++++++++++++++++
>>>  drivers/pci/controller/cadence/pcie-cadence.h      |  9 ++++++-
>>>  2 files changed, 39 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> b/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> index 4550e0d469ca..2b2ae4e18032 100644
>>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> @@ -77,6 +77,36 @@ static struct pci_ops cdns_pcie_host_ops = {
>>>  	.write		= pci_generic_config_write,
>>>  };
>>>
>>> +static void cdns_pcie_retrain(struct cdns_pcie *pcie) {
>>> +	u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
>>> +	u16 lnk_stat, lnk_ctl;
>>> +
>>> +	if (!cdns_pcie_link_up(pcie))
>>> +		return;
>>> +
>>
>> Is there a IP version that can be used to check if that quirk is applicable?
> There is no such provision.

hmm okay. Can we add a DT property to indicate the quirk then since
AFAIK this is not required in future revisions of IP.
>>> +	/*
>>> +	 * Set retrain bit if current speed is 2.5 GB/s,
>>> +	 * but the PCIe root port support is > 2.5 GB/s.
>>> +	 */
>>> +
>>> +	lnk_cap_sls = cdns_pcie_readl(pcie, (CDNS_PCIE_RP_BASE +
>> pcie_cap_off +
>>> +				      PCI_EXP_LNKCAP));
>>> +	if ((lnk_cap_sls & PCI_EXP_LNKCAP_SLS) <=
>> PCI_EXP_LNKCAP_SLS_2_5GB)
>>> +		return;
>>> +
>>> +	lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off +
>> PCI_EXP_LNKSTA);
>>> +	if ((lnk_stat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB)
>> {
>>> +		lnk_ctl = cdns_pcie_rp_readw(pcie,
>>> +					     pcie_cap_off + PCI_EXP_LNKCTL);
>>> +		lnk_ctl |= PCI_EXP_LNKCTL_RL;
>>> +		cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
>>> +				    lnk_ctl);
>>> +
>>> +		if (!cdns_pcie_link_up(pcie))
>>
>> Should this rather be a cdns_pcie_host_wait_for_link()?
> The use of this api cdns_pcie_link_up was mentioned in earlier reviews.
> The mentioned api cdns_pcie_host_wait_for_link is a wrapper in which there are multiple checks.
> If insist, will replace with it.

yeah, I think we should give some time for the link up to succeed after
re-training.

Thanks
Kishon
Rob Herring Oct. 26, 2020, 7:20 p.m. UTC | #4
On Fri, Oct 23, 2020 at 1:57 AM Kishon Vijay Abraham I <kishon@ti.com> wrote:
>
> Hi Nadeem,
>
> On 19/10/20 10:48 pm, Athani Nadeem Ladkhan wrote:
> > Hi Kishon,
> >
> >> -----Original Message-----
> >> From: Kishon Vijay Abraham I <kishon@ti.com>
> >> Sent: Monday, October 19, 2020 10:59 AM
> >> To: Athani Nadeem Ladkhan <nadeem@cadence.com>;
> >> lorenzo.pieralisi@arm.com; robh@kernel.org; bhelgaas@google.com; linux-
> >> pci@vger.kernel.org; linux-kernel@vger.kernel.org; Tom Joseph
> >> <tjoseph@cadence.com>
> >> Cc: Swapnil Kashinath Jakhade <sjakhade@cadence.com>; Milind Parab
> >> <mparab@cadence.com>
> >> Subject: Re: [PATCH v3] PCI: cadence: Retrain Link to work around Gen2
> >> training defect.
> >>
> >> EXTERNAL MAIL
> >>
> >>
> >> Hi Nadeem,
> >>
> >> On 30/09/20 11:51 pm, Nadeem Athani wrote:
> >>> Cadence controller will not initiate autonomous speed change if
> >>> strapped as Gen2. The Retrain Link bit is set as quirk to enable this speed
> >> change.
> >>>
> >>> Signed-off-by: Nadeem Athani <nadeem@cadence.com>
> >>> ---
> >>> Changes in v3:
> >>> - To set retrain link bit,checking device capability & link status.
> >>> - 32bit read in place of 8bit.
> >>> - Minor correction in patch comment.
> >>> - Change in variable & macro name.
> >>> Changes in v2:
> >>> - 16bit read in place of 8bit.
> >>>  drivers/pci/controller/cadence/pcie-cadence-host.c | 31
> >> ++++++++++++++++++++++
> >>>  drivers/pci/controller/cadence/pcie-cadence.h      |  9 ++++++-
> >>>  2 files changed, 39 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c
> >>> b/drivers/pci/controller/cadence/pcie-cadence-host.c
> >>> index 4550e0d469ca..2b2ae4e18032 100644
> >>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> >>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> >>> @@ -77,6 +77,36 @@ static struct pci_ops cdns_pcie_host_ops = {
> >>>     .write          = pci_generic_config_write,
> >>>  };
> >>>
> >>> +static void cdns_pcie_retrain(struct cdns_pcie *pcie) {
> >>> +   u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
> >>> +   u16 lnk_stat, lnk_ctl;
> >>> +
> >>> +   if (!cdns_pcie_link_up(pcie))
> >>> +           return;
> >>> +
> >>
> >> Is there a IP version that can be used to check if that quirk is applicable?
> > There is no such provision.

Cadence just gives out unversioned IP? There may not be s/w readable
version, but there's still a version. Look at DWC.

> hmm okay. Can we add a DT property to indicate the quirk then since
> AFAIK this is not required in future revisions of IP.

No, add a driver quirk flag, but set flag that based on compatible strings.

> >>> +   /*
> >>> +    * Set retrain bit if current speed is 2.5 GB/s,
> >>> +    * but the PCIe root port support is > 2.5 GB/s.

Though wouldn't setting the retrain bit be harmless even if not needed?

Rob
Kishon Vijay Abraham I Nov. 26, 2020, 1:58 p.m. UTC | #5
Hi Tom, Nadeem,

On 27/10/20 12:50 am, Rob Herring wrote:
> On Fri, Oct 23, 2020 at 1:57 AM Kishon Vijay Abraham I <kishon@ti.com> wrote:
>>
>> Hi Nadeem,
>>
>> On 19/10/20 10:48 pm, Athani Nadeem Ladkhan wrote:
>>> Hi Kishon,
>>>
>>>> -----Original Message-----
>>>> From: Kishon Vijay Abraham I <kishon@ti.com>
>>>> Sent: Monday, October 19, 2020 10:59 AM
>>>> To: Athani Nadeem Ladkhan <nadeem@cadence.com>;
>>>> lorenzo.pieralisi@arm.com; robh@kernel.org; bhelgaas@google.com; linux-
>>>> pci@vger.kernel.org; linux-kernel@vger.kernel.org; Tom Joseph
>>>> <tjoseph@cadence.com>
>>>> Cc: Swapnil Kashinath Jakhade <sjakhade@cadence.com>; Milind Parab
>>>> <mparab@cadence.com>
>>>> Subject: Re: [PATCH v3] PCI: cadence: Retrain Link to work around Gen2
>>>> training defect.
>>>>
>>>> EXTERNAL MAIL
>>>>
>>>>
>>>> Hi Nadeem,
>>>>
>>>> On 30/09/20 11:51 pm, Nadeem Athani wrote:
>>>>> Cadence controller will not initiate autonomous speed change if
>>>>> strapped as Gen2. The Retrain Link bit is set as quirk to enable this speed
>>>> change.
>>>>>
>>>>> Signed-off-by: Nadeem Athani <nadeem@cadence.com>

Do you have a follow-up patch fixing the review comments?

Thanks
Kishon
diff mbox series

Patch

diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 4550e0d469ca..2b2ae4e18032 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -77,6 +77,36 @@  static struct pci_ops cdns_pcie_host_ops = {
 	.write		= pci_generic_config_write,
 };
 
+static void cdns_pcie_retrain(struct cdns_pcie *pcie)
+{
+	u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
+	u16 lnk_stat, lnk_ctl;
+
+	if (!cdns_pcie_link_up(pcie))
+		return;
+
+	/*
+	 * Set retrain bit if current speed is 2.5 GB/s,
+	 * but the PCIe root port support is > 2.5 GB/s.
+	 */
+
+	lnk_cap_sls = cdns_pcie_readl(pcie, (CDNS_PCIE_RP_BASE + pcie_cap_off +
+				      PCI_EXP_LNKCAP));
+	if ((lnk_cap_sls & PCI_EXP_LNKCAP_SLS) <= PCI_EXP_LNKCAP_SLS_2_5GB)
+		return;
+
+	lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA);
+	if ((lnk_stat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB) {
+		lnk_ctl = cdns_pcie_rp_readw(pcie,
+					     pcie_cap_off + PCI_EXP_LNKCTL);
+		lnk_ctl |= PCI_EXP_LNKCTL_RL;
+		cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
+				    lnk_ctl);
+
+		if (!cdns_pcie_link_up(pcie))
+			return;
+	}
+}
 
 static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
 {
@@ -115,6 +145,7 @@  static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
 	cdns_pcie_rp_writeb(pcie, PCI_CLASS_PROG, 0);
 	cdns_pcie_rp_writew(pcie, PCI_CLASS_DEVICE, PCI_CLASS_BRIDGE_PCI);
 
+	cdns_pcie_retrain(pcie);
 	return 0;
 }
 
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index feed1e3038f4..5f1cf032ae15 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -119,7 +119,7 @@ 
  * Root Port Registers (PCI configuration space for the root port function)
  */
 #define CDNS_PCIE_RP_BASE	0x00200000
-
+#define CDNS_PCIE_RP_CAP_OFFSET 0xc0
 
 /*
  * Address Translation Registers
@@ -413,6 +413,13 @@  static inline void cdns_pcie_rp_writew(struct cdns_pcie *pcie,
 	cdns_pcie_write_sz(addr, 0x2, value);
 }
 
+static inline u16 cdns_pcie_rp_readw(struct cdns_pcie *pcie, u32 reg)
+{
+	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
+
+	return cdns_pcie_read_sz(addr, 0x2);
+}
+
 /* Endpoint Function register access */
 static inline void cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn,
 					  u32 reg, u8 value)