diff mbox series

[v6,2/4] PCI: dwc: Always cache the maximum link speed value in dw_pcie::max_link_speed

Message ID 20240904-pci-qcom-gen4-stability-v6-2-ec39f7ae3f62@linaro.org (mailing list archive)
State Superseded
Delegated to: Geert Uytterhoeven
Headers show
Series PCI: qcom: Add 16.0 GT/s equalization and margining settings | expand

Commit Message

Manivannan Sadhasivam via B4 Relay Sept. 4, 2024, 7:11 a.m. UTC 
From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Currently, dw_pcie::max_link_speed has a valid value only if the controller
driver restricts the maximum link speed in the driver or if the platform
does so in the devicetree using the 'max-link-speed' property.

But having the maximum supported link speed of the platform would be
helpful for the vendor drivers to configure any link specific settings.
So in the case of non-valid value in dw_pcie::max_link_speed, just cache
the hardware default value from Link Capability register.

While at it, let's also remove the 'max_link_speed' argument to the
dw_pcie_link_set_max_speed() function since the value can be retrieved
within the function.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/pci/controller/dwc/pcie-designware.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

Comments

Johan Hovold Sept. 4, 2024, 9:30 a.m. UTC | #1 
On Wed, Sep 04, 2024 at 12:41:58PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> 
> Currently, dw_pcie::max_link_speed has a valid value only if the controller
> driver restricts the maximum link speed in the driver or if the platform
> does so in the devicetree using the 'max-link-speed' property.
> 
> But having the maximum supported link speed of the platform would be
> helpful for the vendor drivers to configure any link specific settings.
> So in the case of non-valid value in dw_pcie::max_link_speed, just cache
> the hardware default value from Link Capability register.
> 
> While at it, let's also remove the 'max_link_speed' argument to the
> dw_pcie_link_set_max_speed() function since the value can be retrieved
> within the function.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 86c49ba097c6..0704853daa85 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -687,16 +687,27 @@ void dw_pcie_upconfig_setup(struct dw_pcie *pci)
>  }
>  EXPORT_SYMBOL_GPL(dw_pcie_upconfig_setup);
>  
> -static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 max_link_speed)
> +static void dw_pcie_link_set_max_speed(struct dw_pcie *pci)
>  {
>  	u32 cap, ctrl2, link_speed;
>  	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
>  
>  	cap = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +
> +	/*
> +	 * Even if the platform doesn't want to limit the maximum link speed,
> +	 * just cache the hardware default value so that the vendor drivers can
> +	 * use it to do any link specific configuration.
> +	 */
> +	if (pci->max_link_speed < 0) {

This should be 

	if (pci->max_link_speed < 1) {

but the patch works as-is because of the default case in the switch
below which falls back to PCI_EXP_LNKCAP_SLS.

> +		pci->max_link_speed = FIELD_GET(PCI_EXP_LNKCAP_SLS, cap);
> +		return;
> +	}
> +
>  	ctrl2 = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCTL2);
>  	ctrl2 &= ~PCI_EXP_LNKCTL2_TLS;
>  
> -	switch (pcie_link_speed[max_link_speed]) {
> +	switch (pcie_link_speed[pci->max_link_speed]) {
>  	case PCIE_SPEED_2_5GT:
>  		link_speed = PCI_EXP_LNKCTL2_TLS_2_5GT;
>  		break;

> @@ -1058,8 +1069,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
>  {
>  	u32 val;
>  
> -	if (pci->max_link_speed > 0)
> -		dw_pcie_link_set_max_speed(pci, pci->max_link_speed);
> +	dw_pcie_link_set_max_speed(pci);

With the above fixed:

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Manivannan Sadhasivam Sept. 4, 2024, 3:49 p.m. UTC | #2 
On Wed, Sep 04, 2024 at 11:30:08AM +0200, Johan Hovold wrote:
> On Wed, Sep 04, 2024 at 12:41:58PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> > From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > 
> > Currently, dw_pcie::max_link_speed has a valid value only if the controller
> > driver restricts the maximum link speed in the driver or if the platform
> > does so in the devicetree using the 'max-link-speed' property.
> > 
> > But having the maximum supported link speed of the platform would be
> > helpful for the vendor drivers to configure any link specific settings.
> > So in the case of non-valid value in dw_pcie::max_link_speed, just cache
> > the hardware default value from Link Capability register.
> > 
> > While at it, let's also remove the 'max_link_speed' argument to the
> > dw_pcie_link_set_max_speed() function since the value can be retrieved
> > within the function.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> >  drivers/pci/controller/dwc/pcie-designware.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 86c49ba097c6..0704853daa85 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -687,16 +687,27 @@ void dw_pcie_upconfig_setup(struct dw_pcie *pci)
> >  }
> >  EXPORT_SYMBOL_GPL(dw_pcie_upconfig_setup);
> >  
> > -static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 max_link_speed)
> > +static void dw_pcie_link_set_max_speed(struct dw_pcie *pci)
> >  {
> >  	u32 cap, ctrl2, link_speed;
> >  	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> >  
> >  	cap = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> > +
> > +	/*
> > +	 * Even if the platform doesn't want to limit the maximum link speed,
> > +	 * just cache the hardware default value so that the vendor drivers can
> > +	 * use it to do any link specific configuration.
> > +	 */
> > +	if (pci->max_link_speed < 0) {
> 
> This should be 
> 
> 	if (pci->max_link_speed < 1) {
> 

Well I was trying to catch the error value here because if neither driver nor
platform limits the max link speed, this would have -EINVAL (returned by
of_pci_get_max_link_speed()).

But logically it makes sense to use 'pci->max_link_speed < 1' since anything
below value 1 is an invalid value.

Will change it.

- Mani

> but the patch works as-is because of the default case in the switch
> below which falls back to PCI_EXP_LNKCAP_SLS.
> 
> > +		pci->max_link_speed = FIELD_GET(PCI_EXP_LNKCAP_SLS, cap);
> > +		return;
> > +	}
> > +
> >  	ctrl2 = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCTL2);
> >  	ctrl2 &= ~PCI_EXP_LNKCTL2_TLS;
> >  
> > -	switch (pcie_link_speed[max_link_speed]) {
> > +	switch (pcie_link_speed[pci->max_link_speed]) {
> >  	case PCIE_SPEED_2_5GT:
> >  		link_speed = PCI_EXP_LNKCTL2_TLS_2_5GT;
> >  		break;
> 
> > @@ -1058,8 +1069,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
> >  {
> >  	u32 val;
> >  
> > -	if (pci->max_link_speed > 0)
> > -		dw_pcie_link_set_max_speed(pci, pci->max_link_speed);
> > +	dw_pcie_link_set_max_speed(pci);
> 
> With the above fixed:
> 
> Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Frank Li Sept. 4, 2024, 4:01 p.m. UTC | #3 
On Wed, Sep 04, 2024 at 12:41:58PM +0530, Manivannan Sadhasivam wrote:
> Currently, dw_pcie::max_link_speed has a valid value only if the controller
> driver restricts the maximum link speed in the driver or if the platform
> does so in the devicetree using the 'max-link-speed' property.
>
> But having the maximum supported link speed of the platform would be
> helpful for the vendor drivers to configure any link specific settings.
> So in the case of non-valid value in dw_pcie::max_link_speed, just cache
> the hardware default value from Link Capability register.
>
> While at it, let's also remove the 'max_link_speed' argument to the
> dw_pcie_link_set_max_speed() function since the value can be retrieved
> within the function.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 86c49ba097c6..0704853daa85 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -687,16 +687,27 @@ void dw_pcie_upconfig_setup(struct dw_pcie *pci)
>  }
>  EXPORT_SYMBOL_GPL(dw_pcie_upconfig_setup);
>
> -static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 max_link_speed)
> +static void dw_pcie_link_set_max_speed(struct dw_pcie *pci)
>  {
>  	u32 cap, ctrl2, link_speed;
>  	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
>
>  	cap = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +
> +	/*
> +	 * Even if the platform doesn't want to limit the maximum link speed,
> +	 * just cache the hardware default value so that the vendor drivers can
> +	 * use it to do any link specific configuration.
> +	 */
> +	if (pci->max_link_speed < 0) {
> +		pci->max_link_speed = FIELD_GET(PCI_EXP_LNKCAP_SLS, cap);
> +		return;
> +	}
> +
>  	ctrl2 = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCTL2);
>  	ctrl2 &= ~PCI_EXP_LNKCTL2_TLS;
>
> -	switch (pcie_link_speed[max_link_speed]) {
> +	switch (pcie_link_speed[pci->max_link_speed]) {
>  	case PCIE_SPEED_2_5GT:
>  		link_speed = PCI_EXP_LNKCTL2_TLS_2_5GT;
>  		break;
> @@ -1058,8 +1069,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
>  {
>  	u32 val;
>
> -	if (pci->max_link_speed > 0)
> -		dw_pcie_link_set_max_speed(pci, pci->max_link_speed);
> +	dw_pcie_link_set_max_speed(pci);
>
>  	/* Configure Gen1 N_FTS */
>  	if (pci->n_fts[0]) {
>
> --
> 2.25.1
>
Johan Hovold Sept. 5, 2024, 6:45 a.m. UTC | #4 
On Wed, Sep 04, 2024 at 09:19:44PM +0530, Manivannan Sadhasivam wrote:
> On Wed, Sep 04, 2024 at 11:30:08AM +0200, Johan Hovold wrote:
> > On Wed, Sep 04, 2024 at 12:41:58PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> > > From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

> > > +	/*
> > > +	 * Even if the platform doesn't want to limit the maximum link speed,
> > > +	 * just cache the hardware default value so that the vendor drivers can
> > > +	 * use it to do any link specific configuration.
> > > +	 */
> > > +	if (pci->max_link_speed < 0) {
> > 
> > This should be 
> > 
> > 	if (pci->max_link_speed < 1) {
> > 
> 
> Well I was trying to catch the error value here because if neither driver nor
> platform limits the max link speed, this would have -EINVAL (returned by
> of_pci_get_max_link_speed()).

Indeed, I thought I'd traced it do be zero here, but I must have made a
mistake. The old code did check for 0 before calling this function,
though (e.g. in case max_link_speed was never initialised as intended).

> But logically it makes sense to use 'pci->max_link_speed < 1' since anything
> below value 1 is an invalid value.
> 
> Will change it.

Sounds good.

> > > @@ -1058,8 +1069,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
> > >  {
> > >  	u32 val;
> > >  
> > > -	if (pci->max_link_speed > 0)
> > > -		dw_pcie_link_set_max_speed(pci, pci->max_link_speed);
> > > +	dw_pcie_link_set_max_speed(pci);

Johan
diff mbox series

Patch

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 86c49ba097c6..0704853daa85 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -687,16 +687,27 @@  void dw_pcie_upconfig_setup(struct dw_pcie *pci)
 }
 EXPORT_SYMBOL_GPL(dw_pcie_upconfig_setup);
 
-static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 max_link_speed)
+static void dw_pcie_link_set_max_speed(struct dw_pcie *pci)
 {
 	u32 cap, ctrl2, link_speed;
 	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
 
 	cap = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
+
+	/*
+	 * Even if the platform doesn't want to limit the maximum link speed,
+	 * just cache the hardware default value so that the vendor drivers can
+	 * use it to do any link specific configuration.
+	 */
+	if (pci->max_link_speed < 0) {
+		pci->max_link_speed = FIELD_GET(PCI_EXP_LNKCAP_SLS, cap);
+		return;
+	}
+
 	ctrl2 = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCTL2);
 	ctrl2 &= ~PCI_EXP_LNKCTL2_TLS;
 
-	switch (pcie_link_speed[max_link_speed]) {
+	switch (pcie_link_speed[pci->max_link_speed]) {
 	case PCIE_SPEED_2_5GT:
 		link_speed = PCI_EXP_LNKCTL2_TLS_2_5GT;
 		break;
@@ -1058,8 +1069,7 @@  void dw_pcie_setup(struct dw_pcie *pci)
 {
 	u32 val;
 
-	if (pci->max_link_speed > 0)
-		dw_pcie_link_set_max_speed(pci, pci->max_link_speed);
+	dw_pcie_link_set_max_speed(pci);
 
 	/* Configure Gen1 N_FTS */
 	if (pci->n_fts[0]) {