diff mbox series

[v3,2/2] PCI: mediatek-gen3: Add support for restricting link width

Message ID 20240918081307.51264-3-angelogioacchino.delregno@collabora.com (mailing list archive)
State Superseded
Delegated to: Krzysztof Wilczyński
Headers show
Series PCI: mediatek-gen3: Support limiting link speed and width | expand

Commit Message

AngeloGioacchino Del Regno Sept. 18, 2024, 8:13 a.m. UTC 
Add support for restricting the port's link width by specifying
the num-lanes devicetree property in the PCIe node.

The setting is done in the GEN_SETTINGS register (in the driver
named as PCIE_SETTING_REG), where each set bit in [11:8] activates
a set of lanes (from bits 11 to 8 respectively, x16/x8/x4/x2).

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/pci/controller/pcie-mediatek-gen3.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

Comments

Fei Shao Sept. 23, 2024, 10:08 a.m. UTC | #1 
On Wed, Sep 18, 2024 at 4:13 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> Add support for restricting the port's link width by specifying
> the num-lanes devicetree property in the PCIe node.
>
> The setting is done in the GEN_SETTINGS register (in the driver
> named as PCIE_SETTING_REG), where each set bit in [11:8] activates
> a set of lanes (from bits 11 to 8 respectively, x16/x8/x4/x2).
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Reviewed-by: Fei Shao <fshao@chromium.org>
Manivannan Sadhasivam Nov. 2, 2024, 5:24 p.m. UTC | #2 
On Wed, Sep 18, 2024 at 10:13:07AM +0200, AngeloGioacchino Del Regno wrote:
> Add support for restricting the port's link width by specifying
> the num-lanes devicetree property in the PCIe node.
> 
> The setting is done in the GEN_SETTINGS register (in the driver
> named as PCIE_SETTING_REG), where each set bit in [11:8] activates
> a set of lanes (from bits 11 to 8 respectively, x16/x8/x4/x2).
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/pci/controller/pcie-mediatek-gen3.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> index 8d4b045633da..8dd2e5135b01 100644
> --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> @@ -32,6 +32,7 @@
>  #define PCIE_BASE_CFG_SPEED		GENMASK(15, 8)
>  
>  #define PCIE_SETTING_REG		0x80
> +#define PCIE_SETTING_LINK_WIDTH		GENMASK(11, 8)
>  #define PCIE_SETTING_GEN_SUPPORT	GENMASK(14, 12)
>  #define PCIE_PCI_IDS_1			0x9c
>  #define PCI_CLASS(class)		(class << 8)
> @@ -168,6 +169,7 @@ struct mtk_msi_set {
>   * @clks: PCIe clocks
>   * @num_clks: PCIe clocks count for this port
>   * @max_link_speed: Maximum link speed (PCIe Gen) for this port
> + * @num_lanes: Number of PCIe lanes for this port
>   * @irq: PCIe controller interrupt number
>   * @saved_irq_state: IRQ enable state saved at suspend time
>   * @irq_lock: lock protecting IRQ register access
> @@ -189,6 +191,7 @@ struct mtk_gen3_pcie {
>  	struct clk_bulk_data *clks;
>  	int num_clks;
>  	u8 max_link_speed;
> +	u8 num_lanes;
>  
>  	int irq;
>  	u32 saved_irq_state;
> @@ -401,6 +404,14 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
>  			val |= FIELD_PREP(PCIE_SETTING_GEN_SUPPORT,
>  					  GENMASK(pcie->max_link_speed - 2, 0));
>  	}
> +	if (pcie->num_lanes) {
> +		val &= ~PCIE_SETTING_LINK_WIDTH;
> +
> +		/* Zero means one lane, each bit activates x2/x4/x8/x16 */
> +		if (pcie->num_lanes > 1)
> +			val |= FIELD_PREP(PCIE_SETTING_LINK_WIDTH,
> +					  GENMASK(pcie->num_lanes >> 1, 0));
> +	};
>  	writel_relaxed(val, pcie->base + PCIE_SETTING_REG);
>  
>  	/* Set Link Control 2 (LNKCTL2) speed restriction, if any */
> @@ -838,6 +849,7 @@ static int mtk_pcie_parse_port(struct mtk_gen3_pcie *pcie)
>  	struct device *dev = pcie->dev;
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct resource *regs;
> +	u32 num_lanes;
>  
>  	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM, "pcie-mac");
>  	if (!regs)
> @@ -883,6 +895,14 @@ static int mtk_pcie_parse_port(struct mtk_gen3_pcie *pcie)
>  		return pcie->num_clks;
>  	}
>  
> +	ret = of_property_read_u32(dev->of_node, "num-lanes", &num_lanes);
> +	if (ret == 0) {
> +		if (num_lanes == 0 || num_lanes > 16 || (num_lanes != 1 && num_lanes % 2))
> +			dev_warn(dev, "Invalid num-lanes, using controller defaults\n");
> +		else
> +			pcie->num_lanes = num_lanes;
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 2.46.0
> 
>
Jianjun Wang (王建军) Nov. 4, 2024, 8:56 a.m. UTC | #3 
Hi Angelo,

Thanks for your patch.

On Wed, 2024-09-18 at 10:13 +0200, AngeloGioacchino Del Regno wrote:
> Add support for restricting the port's link width by specifying
> the num-lanes devicetree property in the PCIe node.
> 
> The setting is done in the GEN_SETTINGS register (in the driver
> named as PCIE_SETTING_REG), where each set bit in [11:8] activates
> a set of lanes (from bits 11 to 8 respectively, x16/x8/x4/x2).
> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/pci/controller/pcie-mediatek-gen3.c | 20
> ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c
> b/drivers/pci/controller/pcie-mediatek-gen3.c
> index 8d4b045633da..8dd2e5135b01 100644
> --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> @@ -32,6 +32,7 @@
>  #define PCIE_BASE_CFG_SPEED		GENMASK(15, 8)
>  
>  #define PCIE_SETTING_REG		0x80
> +#define PCIE_SETTING_LINK_WIDTH		GENMASK(11, 8)
>  #define PCIE_SETTING_GEN_SUPPORT	GENMASK(14, 12)
>  #define PCIE_PCI_IDS_1			0x9c
>  #define PCI_CLASS(class)		(class << 8)
> @@ -168,6 +169,7 @@ struct mtk_msi_set {
>   * @clks: PCIe clocks
>   * @num_clks: PCIe clocks count for this port
>   * @max_link_speed: Maximum link speed (PCIe Gen) for this port
> + * @num_lanes: Number of PCIe lanes for this port
>   * @irq: PCIe controller interrupt number
>   * @saved_irq_state: IRQ enable state saved at suspend time
>   * @irq_lock: lock protecting IRQ register access
> @@ -189,6 +191,7 @@ struct mtk_gen3_pcie {
>  	struct clk_bulk_data *clks;
>  	int num_clks;
>  	u8 max_link_speed;
> +	u8 num_lanes;
>  
>  	int irq;
>  	u32 saved_irq_state;
> @@ -401,6 +404,14 @@ static int mtk_pcie_startup_port(struct
> mtk_gen3_pcie *pcie)
>  			val |= FIELD_PREP(PCIE_SETTING_GEN_SUPPORT,
>  					  GENMASK(pcie->max_link_speed
> - 2, 0));
>  	}
> +	if (pcie->num_lanes) {
> +		val &= ~PCIE_SETTING_LINK_WIDTH;
> +
> +		/* Zero means one lane, each bit activates x2/x4/x8/x16
> */
> +		if (pcie->num_lanes > 1)
> +			val |= FIELD_PREP(PCIE_SETTING_LINK_WIDTH,
> +					  GENMASK(pcie->num_lanes >> 1,
> 0));

It should be GENMASK(fls(pcie->num_lanes) - 2, 0).

Thanks.

> +	};
>  	writel_relaxed(val, pcie->base + PCIE_SETTING_REG);
>  
>  	/* Set Link Control 2 (LNKCTL2) speed restriction, if any */
> @@ -838,6 +849,7 @@ static int mtk_pcie_parse_port(struct
> mtk_gen3_pcie *pcie)
>  	struct device *dev = pcie->dev;
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct resource *regs;
> +	u32 num_lanes;
>  
>  	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> "pcie-mac");
>  	if (!regs)
> @@ -883,6 +895,14 @@ static int mtk_pcie_parse_port(struct
> mtk_gen3_pcie *pcie)
>  		return pcie->num_clks;
>  	}
>  
> +	ret = of_property_read_u32(dev->of_node, "num-lanes",
> &num_lanes);
> +	if (ret == 0) {
> +		if (num_lanes == 0 || num_lanes > 16 || (num_lanes != 1
> && num_lanes % 2))
> +			dev_warn(dev, "Invalid num-lanes, using
> controller defaults\n");
> +		else
> +			pcie->num_lanes = num_lanes;
> +	}
> +
>  	return 0;
>  }
>
AngeloGioacchino Del Regno Nov. 4, 2024, 10:43 a.m. UTC | #4 
Il 04/11/24 09:56, Jianjun Wang (王建军) ha scritto:
> Hi Angelo,
> 
> Thanks for your patch.
> 
> On Wed, 2024-09-18 at 10:13 +0200, AngeloGioacchino Del Regno wrote:
>> Add support for restricting the port's link width by specifying
>> the num-lanes devicetree property in the PCIe node.
>>
>> The setting is done in the GEN_SETTINGS register (in the driver
>> named as PCIE_SETTING_REG), where each set bit in [11:8] activates
>> a set of lanes (from bits 11 to 8 respectively, x16/x8/x4/x2).
>>
>> Signed-off-by: AngeloGioacchino Del Regno <
>> angelogioacchino.delregno@collabora.com>
>> ---
>>   drivers/pci/controller/pcie-mediatek-gen3.c | 20
>> ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c
>> b/drivers/pci/controller/pcie-mediatek-gen3.c
>> index 8d4b045633da..8dd2e5135b01 100644
>> --- a/drivers/pci/controller/pcie-mediatek-gen3.c
>> +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
>> @@ -32,6 +32,7 @@
>>   #define PCIE_BASE_CFG_SPEED		GENMASK(15, 8)
>>   
>>   #define PCIE_SETTING_REG		0x80
>> +#define PCIE_SETTING_LINK_WIDTH		GENMASK(11, 8)
>>   #define PCIE_SETTING_GEN_SUPPORT	GENMASK(14, 12)
>>   #define PCIE_PCI_IDS_1			0x9c
>>   #define PCI_CLASS(class)		(class << 8)
>> @@ -168,6 +169,7 @@ struct mtk_msi_set {
>>    * @clks: PCIe clocks
>>    * @num_clks: PCIe clocks count for this port
>>    * @max_link_speed: Maximum link speed (PCIe Gen) for this port
>> + * @num_lanes: Number of PCIe lanes for this port
>>    * @irq: PCIe controller interrupt number
>>    * @saved_irq_state: IRQ enable state saved at suspend time
>>    * @irq_lock: lock protecting IRQ register access
>> @@ -189,6 +191,7 @@ struct mtk_gen3_pcie {
>>   	struct clk_bulk_data *clks;
>>   	int num_clks;
>>   	u8 max_link_speed;
>> +	u8 num_lanes;
>>   
>>   	int irq;
>>   	u32 saved_irq_state;
>> @@ -401,6 +404,14 @@ static int mtk_pcie_startup_port(struct
>> mtk_gen3_pcie *pcie)
>>   			val |= FIELD_PREP(PCIE_SETTING_GEN_SUPPORT,
>>   					  GENMASK(pcie->max_link_speed
>> - 2, 0));
>>   	}
>> +	if (pcie->num_lanes) {
>> +		val &= ~PCIE_SETTING_LINK_WIDTH;
>> +
>> +		/* Zero means one lane, each bit activates x2/x4/x8/x16
>> */
>> +		if (pcie->num_lanes > 1)
>> +			val |= FIELD_PREP(PCIE_SETTING_LINK_WIDTH,
>> +					  GENMASK(pcie->num_lanes >> 1,
>> 0));
> 
> It should be GENMASK(fls(pcie->num_lanes) - 2, 0).
> 

You're right in that there's a mistake in that one, and I see it now,
but I don't get why this should be "fls(...) - 2".

The datasheet says that "LinkWidths" is

Bit 8 = x2 supported
Bit 9 = x4 supported
Bit 10 = x8 supported
Bit 11 = x16 supported

pcie->num_lanes can be set to either 2, 4, 8 or 16.

2>>2 = 0   -> fls(0) == 0 (after field_prep/genmask: bit 8)
4>>2 = 1   -> fls(1) == 1 (after field_prep/genmask: bit 9 to 8)
8>>2 = 2   -> fls(2) == 2 (after field_prep/genmask: bit 10 to 8)
16>>2 = 4  -> fls(4) == 3 (after field_prep/genmask: bit 11 to 8)

So, this should be
	GENMASK(fls(pcie->num_lanes >> 2), 0)

Right? :-)

In which case, should I send a new version, or can you fix that while
applying? I'd really appreciate the latter due to lack of time.

Cheers,
Angelo

> Thanks.
> 
>> +	};
>>   	writel_relaxed(val, pcie->base + PCIE_SETTING_REG);
>>   
>>   	/* Set Link Control 2 (LNKCTL2) speed restriction, if any */
>> @@ -838,6 +849,7 @@ static int mtk_pcie_parse_port(struct
>> mtk_gen3_pcie *pcie)
>>   	struct device *dev = pcie->dev;
>>   	struct platform_device *pdev = to_platform_device(dev);
>>   	struct resource *regs;
>> +	u32 num_lanes;
>>   
>>   	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> "pcie-mac");
>>   	if (!regs)
>> @@ -883,6 +895,14 @@ static int mtk_pcie_parse_port(struct
>> mtk_gen3_pcie *pcie)
>>   		return pcie->num_clks;
>>   	}
>>   
>> +	ret = of_property_read_u32(dev->of_node, "num-lanes",
>> &num_lanes);
>> +	if (ret == 0) {
>> +		if (num_lanes == 0 || num_lanes > 16 || (num_lanes != 1
>> && num_lanes % 2))
>> +			dev_warn(dev, "Invalid num-lanes, using
>> controller defaults\n");
>> +		else
>> +			pcie->num_lanes = num_lanes;
>> +	}
>> +
>>   	return 0;
>>   }
>>
diff mbox series

Patch

diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
index 8d4b045633da..8dd2e5135b01 100644
--- a/drivers/pci/controller/pcie-mediatek-gen3.c
+++ b/drivers/pci/controller/pcie-mediatek-gen3.c
@@ -32,6 +32,7 @@ 
 #define PCIE_BASE_CFG_SPEED		GENMASK(15, 8)
 
 #define PCIE_SETTING_REG		0x80
+#define PCIE_SETTING_LINK_WIDTH		GENMASK(11, 8)
 #define PCIE_SETTING_GEN_SUPPORT	GENMASK(14, 12)
 #define PCIE_PCI_IDS_1			0x9c
 #define PCI_CLASS(class)		(class << 8)
@@ -168,6 +169,7 @@  struct mtk_msi_set {
  * @clks: PCIe clocks
  * @num_clks: PCIe clocks count for this port
  * @max_link_speed: Maximum link speed (PCIe Gen) for this port
+ * @num_lanes: Number of PCIe lanes for this port
  * @irq: PCIe controller interrupt number
  * @saved_irq_state: IRQ enable state saved at suspend time
  * @irq_lock: lock protecting IRQ register access
@@ -189,6 +191,7 @@  struct mtk_gen3_pcie {
 	struct clk_bulk_data *clks;
 	int num_clks;
 	u8 max_link_speed;
+	u8 num_lanes;
 
 	int irq;
 	u32 saved_irq_state;
@@ -401,6 +404,14 @@  static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
 			val |= FIELD_PREP(PCIE_SETTING_GEN_SUPPORT,
 					  GENMASK(pcie->max_link_speed - 2, 0));
 	}
+	if (pcie->num_lanes) {
+		val &= ~PCIE_SETTING_LINK_WIDTH;
+
+		/* Zero means one lane, each bit activates x2/x4/x8/x16 */
+		if (pcie->num_lanes > 1)
+			val |= FIELD_PREP(PCIE_SETTING_LINK_WIDTH,
+					  GENMASK(pcie->num_lanes >> 1, 0));
+	};
 	writel_relaxed(val, pcie->base + PCIE_SETTING_REG);
 
 	/* Set Link Control 2 (LNKCTL2) speed restriction, if any */
@@ -838,6 +849,7 @@  static int mtk_pcie_parse_port(struct mtk_gen3_pcie *pcie)
 	struct device *dev = pcie->dev;
 	struct platform_device *pdev = to_platform_device(dev);
 	struct resource *regs;
+	u32 num_lanes;
 
 	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM, "pcie-mac");
 	if (!regs)
@@ -883,6 +895,14 @@  static int mtk_pcie_parse_port(struct mtk_gen3_pcie *pcie)
 		return pcie->num_clks;
 	}
 
+	ret = of_property_read_u32(dev->of_node, "num-lanes", &num_lanes);
+	if (ret == 0) {
+		if (num_lanes == 0 || num_lanes > 16 || (num_lanes != 1 && num_lanes % 2))
+			dev_warn(dev, "Invalid num-lanes, using controller defaults\n");
+		else
+			pcie->num_lanes = num_lanes;
+	}
+
 	return 0;
 }