PCI: rockchip: Support quirk to disable 5 GT/s (PCIe 2.x) link rate
diff mbox

Message ID 1474565478-27242-1-git-send-email-briannorris@chromium.org
State New
Headers show

Commit Message

Brian Norris Sept. 22, 2016, 5:31 p.m. UTC
rk3399 supports PCIe 2.x link speeds marginally at best, and on some
boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
ms waiting for training that will never happen, let's support a device
tree quirk flag to disable generation 2 speeds entirely.

Signed-off-by: Brian Norris <briannorris@chromium.org>
---
 .../devicetree/bindings/pci/rockchip-pcie.txt      |  2 +
 drivers/pci/host/pcie-rockchip.c                   | 57 +++++++++++++---------
 2 files changed, 37 insertions(+), 22 deletions(-)

Comments

Shawn Lin Sept. 23, 2016, 12:27 a.m. UTC | #1
Hi Brain,

在 2016/9/23 1:31, Brian Norris 写道:
> rk3399 supports PCIe 2.x link speeds marginally at best, and on some
> boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
> ms waiting for training that will never happen, let's support a device
> tree quirk flag to disable generation 2 speeds entirely.

I was thinking about could we get target link speed [TLS] from the
end-point when finishing Gen1 training, but it seems that the location
of ep's TLS is not fixed.

Anyway, your patch looks sane to me as we leave gen2 as default and
people could drop that feature by adding rockchip,disable-gen2 to
their dts if they are sure the board would never supoort Gen2 devices.

Acked-by: Shawn Lin <shawn.lin@rock-chips.com>


>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
>  .../devicetree/bindings/pci/rockchip-pcie.txt      |  2 +
>  drivers/pci/host/pcie-rockchip.c                   | 57 +++++++++++++---------
>  2 files changed, 37 insertions(+), 22 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> index ba67b39939c1..e769726fd093 100644
> --- a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> @@ -42,6 +42,8 @@ Required properties:
>  Optional Property:
>  - ep-gpios: contain the entry for pre-reset gpio
>  - num-lanes: number of lanes to use
> +- rockchip,disable-gen2: present if PCIe generation 2.x (i.e., 5 GT/s link
> +	speeds) is not supported.
>  - vpcie3v3-supply: The phandle to the 3.3v regulator to use for PCIe.
>  - vpcie1v8-supply: The phandle to the 1.8v regulator to use for PCIe.
>  - vpcie0v9-supply: The phandle to the 0.9v regulator to use for PCIe.
> diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
> index c3593e633ccd..f047c4a73f69 100644
> --- a/drivers/pci/host/pcie-rockchip.c
> +++ b/drivers/pci/host/pcie-rockchip.c
> @@ -53,6 +53,7 @@
>  #define   PCIE_CLIENT_ARI_ENABLE	  HIWORD_UPDATE_BIT(0x0008)
>  #define   PCIE_CLIENT_CONF_LANE_NUM(x)	  HIWORD_UPDATE(0x0030, ENCODE_LANES(x))
>  #define   PCIE_CLIENT_MODE_RC		  HIWORD_UPDATE_BIT(0x0040)
> +#define   PCIE_CLIENT_GEN_SEL_1		  HIWORD_UPDATE(0x0080, 0)
>  #define   PCIE_CLIENT_GEN_SEL_2		  HIWORD_UPDATE_BIT(0x0080)
>  #define PCIE_CLIENT_BASIC_STATUS1	(PCIE_CLIENT_BASE + 0x48)
>  #define   PCIE_CLIENT_LINK_STATUS_UP		0x00300000
> @@ -191,6 +192,7 @@ struct rockchip_pcie {
>  	struct	gpio_desc *ep_gpio;
>  	u32	lanes;
>  	u8	root_bus_nr;
> +	bool	enable_gen2;
>  	struct	device *dev;
>  	struct	irq_domain *irq_domain;
>  };
> @@ -418,13 +420,19 @@ static int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
>  		return err;
>  	}
>
> +	if (rockchip->enable_gen2)
> +		rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_2,
> +				    PCIE_CLIENT_CONFIG);
> +	else
> +		rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_1,
> +				    PCIE_CLIENT_CONFIG);
> +
>  	rockchip_pcie_write(rockchip,
>  			    PCIE_CLIENT_CONF_ENABLE |
>  			    PCIE_CLIENT_LINK_TRAIN_ENABLE |
>  			    PCIE_CLIENT_ARI_ENABLE |
>  			    PCIE_CLIENT_CONF_LANE_NUM(rockchip->lanes) |
> -			    PCIE_CLIENT_MODE_RC |
> -			    PCIE_CLIENT_GEN_SEL_2,
> +			    PCIE_CLIENT_MODE_RC,
>  				PCIE_CLIENT_CONFIG);
>
>  	err = phy_power_on(rockchip->phy);
> @@ -492,29 +500,31 @@ static int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
>  		msleep(20);
>  	}
>
> -	/*
> -	 * Enable retrain for gen2. This should be configured only after
> -	 * gen1 finished.
> -	 */
> -	status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_LCS);
> -	status |= PCIE_RC_CONFIG_LCS_RETRAIN_LINK;
> -	rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_LCS);
> +	if (rockchip->enable_gen2) {
> +		/*
> +		 * Enable retrain for gen2. This should be configured only after
> +		 * gen1 finished.
> +		 */
> +		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_LCS);
> +		status |= PCIE_RC_CONFIG_LCS_RETRAIN_LINK;
> +		rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_LCS);
> +
> +		timeout = jiffies + msecs_to_jiffies(500);
> +		for (;;) {
> +			status = rockchip_pcie_read(rockchip, PCIE_CORE_CTRL);
> +			if ((status & PCIE_CORE_PL_CONF_SPEED_MASK) ==
> +					PCIE_CORE_PL_CONF_SPEED_5G) {
> +				dev_dbg(dev, "PCIe link training gen2 pass!\n");
> +				break;
> +			}
>
> -	timeout = jiffies + msecs_to_jiffies(500);
> -	for (;;) {
> -		status = rockchip_pcie_read(rockchip, PCIE_CORE_CTRL);
> -		if ((status & PCIE_CORE_PL_CONF_SPEED_MASK) ==
> -		    PCIE_CORE_PL_CONF_SPEED_5G) {
> -			dev_dbg(dev, "PCIe link training gen2 pass!\n");
> -			break;
> -		}
> +			if (time_after(jiffies, timeout)) {
> +				dev_dbg(dev, "PCIe link training gen2 timeout, fall back to gen1!\n");
> +				break;
> +			}
>
> -		if (time_after(jiffies, timeout)) {
> -			dev_dbg(dev, "PCIe link training gen2 timeout, fall back to gen1!\n");
> -			break;
> +			msleep(20);
>  		}
> -
> -		msleep(20);
>  	}
>
>  	/* Check the final link width from negotiated lane counter from MGMT */
> @@ -722,6 +732,9 @@ static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
>  		rockchip->lanes = 1;
>  	}
>
> +	rockchip->enable_gen2 = !of_property_read_bool(node,
> +						       "rockchip,disable-gen2");
> +
>  	rockchip->core_rst = devm_reset_control_get(dev, "core");
>  	if (IS_ERR(rockchip->core_rst)) {
>  		if (PTR_ERR(rockchip->core_rst) != -EPROBE_DEFER)
>
Brian Norris Sept. 23, 2016, 1:15 a.m. UTC | #2
Hi Shawn,

On Fri, Sep 23, 2016 at 08:27:35AM +0800, Shawn Lin wrote:
> 在 2016/9/23 1:31, Brian Norris 写道:
> >rk3399 supports PCIe 2.x link speeds marginally at best, and on some
> >boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
> >ms waiting for training that will never happen, let's support a device
> >tree quirk flag to disable generation 2 speeds entirely.
> 
> I was thinking about could we get target link speed [TLS] from the
> end-point when finishing Gen1 training, but it seems that the location
> of ep's TLS is not fixed.

Indeed it's not, but we could probably handle that if absolutely needed
(get a reference to the root port pci_dev somehow, then use the existing
helpers to walk children and get the computed ->pcie_cap offset). But
that's not the problem here; we have 5 GT/s devices, but they are not
running at 5 GT/s because link training can't pass. We have been told
there are still SI issues, and so you wouldn't really be able to turn
this out at runtime anyway.

But sure, I suppose that'd be a way to (for chips/boards that don't have
SI issues) determine whether or not to attempt gen2 training at all.
That does sound better than just timing out after 500ms...

> Anyway, your patch looks sane to me as we leave gen2 as default and
> people could drop that feature by adding rockchip,disable-gen2 to
> their dts if they are sure the board would never supoort Gen2 devices.
> 
> Acked-by: Shawn Lin <shawn.lin@rock-chips.com>

Thanks.

Brian
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Shawn Lin Sept. 23, 2016, 1:34 a.m. UTC | #3
Hi Brain,

在 2016/9/23 9:15, Brian Norris 写道:
> Hi Shawn,
>
> On Fri, Sep 23, 2016 at 08:27:35AM +0800, Shawn Lin wrote:
>> 在 2016/9/23 1:31, Brian Norris 写道:
>>> rk3399 supports PCIe 2.x link speeds marginally at best, and on some
>>> boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
>>> ms waiting for training that will never happen, let's support a device
>>> tree quirk flag to disable generation 2 speeds entirely.
>>
>> I was thinking about could we get target link speed [TLS] from the
>> end-point when finishing Gen1 training, but it seems that the location
>> of ep's TLS is not fixed.
>
> Indeed it's not, but we could probably handle that if absolutely needed
> (get a reference to the root port pci_dev somehow, then use the existing
> helpers to walk children and get the computed ->pcie_cap offset). But

Right, we could probably walk through the ep's cap and get this, but
sure, it's not the problem here, and that is maybe what I want to dig
more later.

Thanks for sharing this.

> that's not the problem here; we have 5 GT/s devices, but they are not
> running at 5 GT/s because link training can't pass. We have been told
> there are still SI issues, and so you wouldn't really be able to turn
> this out at runtime anyway.
>
> But sure, I suppose that'd be a way to (for chips/boards that don't have
> SI issues) determine whether or not to attempt gen2 training at all.
> That does sound better than just timing out after 500ms...
>
>> Anyway, your patch looks sane to me as we leave gen2 as default and
>> people could drop that feature by adding rockchip,disable-gen2 to
>> their dts if they are sure the board would never supoort Gen2 devices.
>>
>> Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
>
> Thanks.
>
> Brian
>
>
>
Rob Herring Sept. 23, 2016, 9:46 p.m. UTC | #4
On Thu, Sep 22, 2016 at 10:31:18AM -0700, Brian Norris wrote:
> rk3399 supports PCIe 2.x link speeds marginally at best, and on some
> boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
> ms waiting for training that will never happen, let's support a device
> tree quirk flag to disable generation 2 speeds entirely.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
>  .../devicetree/bindings/pci/rockchip-pcie.txt      |  2 +
>  drivers/pci/host/pcie-rockchip.c                   | 57 +++++++++++++---------
>  2 files changed, 37 insertions(+), 22 deletions(-)

Acked-by: Rob Herring <robh@kernel.org>
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Bjorn Helgaas Sept. 23, 2016, 11:55 p.m. UTC | #5
On Thu, Sep 22, 2016 at 10:31:18AM -0700, Brian Norris wrote:
> rk3399 supports PCIe 2.x link speeds marginally at best, and on some
> boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
> ms waiting for training that will never happen, let's support a device
> tree quirk flag to disable generation 2 speeds entirely.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
>  .../devicetree/bindings/pci/rockchip-pcie.txt      |  2 +
>  drivers/pci/host/pcie-rockchip.c                   | 57 +++++++++++++---------
>  2 files changed, 37 insertions(+), 22 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> index ba67b39939c1..e769726fd093 100644
> --- a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> @@ -42,6 +42,8 @@ Required properties:
>  Optional Property:
>  - ep-gpios: contain the entry for pre-reset gpio
>  - num-lanes: number of lanes to use
> +- rockchip,disable-gen2: present if PCIe generation 2.x (i.e., 5 GT/s link
> +	speeds) is not supported.
>  - vpcie3v3-supply: The phandle to the 3.3v regulator to use for PCIe.
>  - vpcie1v8-supply: The phandle to the 1.8v regulator to use for PCIe.
>  - vpcie0v9-supply: The phandle to the 0.9v regulator to use for PCIe.

We already have st,pcie-is-gen1 and fsl,max-link-speed for similar
issues.  Can you copy the naming of one of those?  The
"max-link-speed" one seems a little more general.

Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch
diff mbox

diff --git a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
index ba67b39939c1..e769726fd093 100644
--- a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
@@ -42,6 +42,8 @@  Required properties:
 Optional Property:
 - ep-gpios: contain the entry for pre-reset gpio
 - num-lanes: number of lanes to use
+- rockchip,disable-gen2: present if PCIe generation 2.x (i.e., 5 GT/s link
+	speeds) is not supported.
 - vpcie3v3-supply: The phandle to the 3.3v regulator to use for PCIe.
 - vpcie1v8-supply: The phandle to the 1.8v regulator to use for PCIe.
 - vpcie0v9-supply: The phandle to the 0.9v regulator to use for PCIe.
diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
index c3593e633ccd..f047c4a73f69 100644
--- a/drivers/pci/host/pcie-rockchip.c
+++ b/drivers/pci/host/pcie-rockchip.c
@@ -53,6 +53,7 @@ 
 #define   PCIE_CLIENT_ARI_ENABLE	  HIWORD_UPDATE_BIT(0x0008)
 #define   PCIE_CLIENT_CONF_LANE_NUM(x)	  HIWORD_UPDATE(0x0030, ENCODE_LANES(x))
 #define   PCIE_CLIENT_MODE_RC		  HIWORD_UPDATE_BIT(0x0040)
+#define   PCIE_CLIENT_GEN_SEL_1		  HIWORD_UPDATE(0x0080, 0)
 #define   PCIE_CLIENT_GEN_SEL_2		  HIWORD_UPDATE_BIT(0x0080)
 #define PCIE_CLIENT_BASIC_STATUS1	(PCIE_CLIENT_BASE + 0x48)
 #define   PCIE_CLIENT_LINK_STATUS_UP		0x00300000
@@ -191,6 +192,7 @@  struct rockchip_pcie {
 	struct	gpio_desc *ep_gpio;
 	u32	lanes;
 	u8	root_bus_nr;
+	bool	enable_gen2;
 	struct	device *dev;
 	struct	irq_domain *irq_domain;
 };
@@ -418,13 +420,19 @@  static int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
 		return err;
 	}
 
+	if (rockchip->enable_gen2)
+		rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_2,
+				    PCIE_CLIENT_CONFIG);
+	else
+		rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_1,
+				    PCIE_CLIENT_CONFIG);
+
 	rockchip_pcie_write(rockchip,
 			    PCIE_CLIENT_CONF_ENABLE |
 			    PCIE_CLIENT_LINK_TRAIN_ENABLE |
 			    PCIE_CLIENT_ARI_ENABLE |
 			    PCIE_CLIENT_CONF_LANE_NUM(rockchip->lanes) |
-			    PCIE_CLIENT_MODE_RC |
-			    PCIE_CLIENT_GEN_SEL_2,
+			    PCIE_CLIENT_MODE_RC,
 				PCIE_CLIENT_CONFIG);
 
 	err = phy_power_on(rockchip->phy);
@@ -492,29 +500,31 @@  static int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
 		msleep(20);
 	}
 
-	/*
-	 * Enable retrain for gen2. This should be configured only after
-	 * gen1 finished.
-	 */
-	status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_LCS);
-	status |= PCIE_RC_CONFIG_LCS_RETRAIN_LINK;
-	rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_LCS);
+	if (rockchip->enable_gen2) {
+		/*
+		 * Enable retrain for gen2. This should be configured only after
+		 * gen1 finished.
+		 */
+		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_LCS);
+		status |= PCIE_RC_CONFIG_LCS_RETRAIN_LINK;
+		rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_LCS);
+
+		timeout = jiffies + msecs_to_jiffies(500);
+		for (;;) {
+			status = rockchip_pcie_read(rockchip, PCIE_CORE_CTRL);
+			if ((status & PCIE_CORE_PL_CONF_SPEED_MASK) ==
+					PCIE_CORE_PL_CONF_SPEED_5G) {
+				dev_dbg(dev, "PCIe link training gen2 pass!\n");
+				break;
+			}
 
-	timeout = jiffies + msecs_to_jiffies(500);
-	for (;;) {
-		status = rockchip_pcie_read(rockchip, PCIE_CORE_CTRL);
-		if ((status & PCIE_CORE_PL_CONF_SPEED_MASK) ==
-		    PCIE_CORE_PL_CONF_SPEED_5G) {
-			dev_dbg(dev, "PCIe link training gen2 pass!\n");
-			break;
-		}
+			if (time_after(jiffies, timeout)) {
+				dev_dbg(dev, "PCIe link training gen2 timeout, fall back to gen1!\n");
+				break;
+			}
 
-		if (time_after(jiffies, timeout)) {
-			dev_dbg(dev, "PCIe link training gen2 timeout, fall back to gen1!\n");
-			break;
+			msleep(20);
 		}
-
-		msleep(20);
 	}
 
 	/* Check the final link width from negotiated lane counter from MGMT */
@@ -722,6 +732,9 @@  static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
 		rockchip->lanes = 1;
 	}
 
+	rockchip->enable_gen2 = !of_property_read_bool(node,
+						       "rockchip,disable-gen2");
+
 	rockchip->core_rst = devm_reset_control_get(dev, "core");
 	if (IS_ERR(rockchip->core_rst)) {
 		if (PTR_ERR(rockchip->core_rst) != -EPROBE_DEFER)