[PATCH v2 0/3] PCI: armada8k: Add support for AC5 SoC

[PATCH v2 0/3] PCI: armada8k: Add support for AC5 SoC

[Vadym Kochan]

Add support for AC5 SoC with MSI. There are differences in the registers
addresses.

v2:
   1) add patch with adding compatible string for dt-bindings description

   2) fix W1 warnings which caused by unused leftover code

   3) Use one xlate function to translate ac5 dbi access. Also add
      mode description in comments about this translation.

   4) Use correct name of Raz

   5) Use matching data to pass the SoC specific params (type & ops)
   
Raz Adashi (1):
  PCI: armada8k: Add AC5 SoC support

Vadym Kochan (1):
  dt-bindings: PCI: armada8k: Add compatible string for AC5 SoC

Yuval Shaia (1):
  PCI: armada8k: Add MSI support for AC5 SoC

 .../devicetree/bindings/pci/pci-armada8k.txt  |   4 +-
 drivers/pci/controller/dwc/pcie-armada8k.c    | 171 ++++++++++++++----
 2 files changed, 139 insertions(+), 36 deletions(-)

-- 
2.25.1

[PATCH v2 1/3] dt-bindings: PCI: armada8k: Add compatible string for AC5 SoC

[Vadym Kochan]

AC5 SoC has armada8k PCIe IP so add compatible string for it.

Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
---
v2: no changes

 Documentation/devicetree/bindings/pci/pci-armada8k.txt | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/pci/pci-armada8k.txt b/Documentation/devicetree/bindings/pci/pci-armada8k.txt
index ff25a134befa..b272fa4f08b5 100644
--- a/Documentation/devicetree/bindings/pci/pci-armada8k.txt
+++ b/Documentation/devicetree/bindings/pci/pci-armada8k.txt
@@ -4,7 +4,9 @@ This PCIe host controller is based on the Synopsys DesignWare PCIe IP
 and thus inherits all the common properties defined in snps,dw-pcie.yaml.
 
 Required properties:
-- compatible: "marvell,armada8k-pcie"
+- compatible: Should be set to one of the following:
+   - "marvell,armada8k-pcie" : For A7K/8K family of SoCs
+   - "marvell,ac5-pcie"      : For AC5 family of SoCs
 - reg: must contain two register regions
    - the control register region
    - the config space region
-- 
2.25.1

[PATCH v2 2/3] PCI: armada8k: Add AC5 SoC support

[Vadym Kochan]

From: Raz Adashi <raza@marvell.com>

pcie-armada8k driver is utilized to serve also AC5.

Driver assumes interrupt mask registers are located
in the same address inboth CPUs. This assumption is
incorrect - fix it for AC5.

Co-developed-by: Yuval Shaia <yshaia@marvell.com>
Signed-off-by: Yuval Shaia <yshaia@marvell.com>
Signed-off-by: Raz Adashi <raza@marvell.com>
Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
---
v2:
   1) fix W1 warnings which caused by unused leftover code

   2) Use one xlate function to translate ac5 dbi access. Also add
      mode description in comments about this translation.

   3) Use correct name of Raz

   4) Use matching data to pass the SoC specific params (type & ops)

 drivers/pci/controller/dwc/pcie-armada8k.c | 157 ++++++++++++++++-----
 1 file changed, 119 insertions(+), 38 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-armada8k.c b/drivers/pci/controller/dwc/pcie-armada8k.c
index 5c999e15c357..bbe9a1750d0d 100644
--- a/drivers/pci/controller/dwc/pcie-armada8k.c
+++ b/drivers/pci/controller/dwc/pcie-armada8k.c
@@ -16,6 +16,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/pci.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
@@ -26,15 +27,26 @@
 
 #define ARMADA8K_PCIE_MAX_LANES PCIE_LNK_X4
 
+enum armada8k_pcie_type {
+	ARMADA8K_PCIE_TYPE_A8K,
+	ARMADA8K_PCIE_TYPE_AC5
+};
+
 struct armada8k_pcie {
 	struct dw_pcie *pci;
 	struct clk *clk;
 	struct clk *clk_reg;
 	struct phy *phy[ARMADA8K_PCIE_MAX_LANES];
 	unsigned int phy_count;
+	enum armada8k_pcie_type pcie_type;
 };
 
-#define PCIE_VENDOR_REGS_OFFSET		0x8000
+struct armada8k_pcie_of_data {
+	enum armada8k_pcie_type pcie_type;
+	const struct dw_pcie_ops *pcie_ops;
+};
+
+#define PCIE_VENDOR_REGS_OFFSET		0x8000	/* in ac5 is 0x10000 */
 
 #define PCIE_GLOBAL_CONTROL_REG		(PCIE_VENDOR_REGS_OFFSET + 0x0)
 #define PCIE_APP_LTSSM_EN		BIT(2)
@@ -48,10 +60,17 @@ struct armada8k_pcie {
 
 #define PCIE_GLOBAL_INT_CAUSE1_REG	(PCIE_VENDOR_REGS_OFFSET + 0x1C)
 #define PCIE_GLOBAL_INT_MASK1_REG	(PCIE_VENDOR_REGS_OFFSET + 0x20)
+#define PCIE_GLOBAL_INT_MASK2_REG	(PCIE_VENDOR_REGS_OFFSET + 0x28)
 #define PCIE_INT_A_ASSERT_MASK		BIT(9)
 #define PCIE_INT_B_ASSERT_MASK		BIT(10)
 #define PCIE_INT_C_ASSERT_MASK		BIT(11)
 #define PCIE_INT_D_ASSERT_MASK		BIT(12)
+#define PCIE_INT_A_ASSERT_MASK_AC5	BIT(12)
+#define PCIE_INT_B_ASSERT_MASK_AC5	BIT(13)
+#define PCIE_INT_C_ASSERT_MASK_AC5	BIT(14)
+#define PCIE_INT_D_ASSERT_MASK_AC5	BIT(15)
+
+#define PCIE_ATU_ACCESS_MASK_AC5	GENMASK(21, 20)
 
 #define PCIE_ARCACHE_TRC_REG		(PCIE_VENDOR_REGS_OFFSET + 0x50)
 #define PCIE_AWCACHE_TRC_REG		(PCIE_VENDOR_REGS_OFFSET + 0x54)
@@ -153,22 +172,11 @@ static int armada8k_pcie_link_up(struct dw_pcie *pci)
 	return 0;
 }
 
-static int armada8k_pcie_start_link(struct dw_pcie *pci)
-{
-	u32 reg;
-
-	/* Start LTSSM */
-	reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_CONTROL_REG);
-	reg |= PCIE_APP_LTSSM_EN;
-	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
-
-	return 0;
-}
-
 static int armada8k_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	u32 reg;
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct armada8k_pcie *pcie = to_armada8k_pcie(pci);
 
 	if (!dw_pcie_link_up(pci)) {
 		/* Disable LTSSM state machine to enable configuration */
@@ -177,32 +185,41 @@ static int armada8k_pcie_host_init(struct dw_pcie_rp *pp)
 		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
 	}
 
-	/* Set the device to root complex mode */
-	reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_CONTROL_REG);
-	reg &= ~(PCIE_DEVICE_TYPE_MASK << PCIE_DEVICE_TYPE_SHIFT);
-	reg |= PCIE_DEVICE_TYPE_RC << PCIE_DEVICE_TYPE_SHIFT;
-	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
+	if (pcie->pcie_type == ARMADA8K_PCIE_TYPE_A8K) {
+		/* Set the device to root complex mode */
+		reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_CONTROL_REG);
+		reg &= ~(PCIE_DEVICE_TYPE_MASK << PCIE_DEVICE_TYPE_SHIFT);
+		reg |= PCIE_DEVICE_TYPE_RC << PCIE_DEVICE_TYPE_SHIFT;
+		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
 
-	/* Set the PCIe master AxCache attributes */
-	dw_pcie_writel_dbi(pci, PCIE_ARCACHE_TRC_REG, ARCACHE_DEFAULT_VALUE);
-	dw_pcie_writel_dbi(pci, PCIE_AWCACHE_TRC_REG, AWCACHE_DEFAULT_VALUE);
+		/* Set the PCIe master AxCache attributes */
+		dw_pcie_writel_dbi(pci, PCIE_ARCACHE_TRC_REG, ARCACHE_DEFAULT_VALUE);
+		dw_pcie_writel_dbi(pci, PCIE_AWCACHE_TRC_REG, AWCACHE_DEFAULT_VALUE);
 
-	/* Set the PCIe master AxDomain attributes */
-	reg = dw_pcie_readl_dbi(pci, PCIE_ARUSER_REG);
-	reg &= ~(AX_USER_DOMAIN_MASK << AX_USER_DOMAIN_SHIFT);
-	reg |= DOMAIN_OUTER_SHAREABLE << AX_USER_DOMAIN_SHIFT;
-	dw_pcie_writel_dbi(pci, PCIE_ARUSER_REG, reg);
+		/* Set the PCIe master AxDomain attributes */
+		reg = dw_pcie_readl_dbi(pci, PCIE_ARUSER_REG);
+		reg &= ~(AX_USER_DOMAIN_MASK << AX_USER_DOMAIN_SHIFT);
+		reg |= DOMAIN_OUTER_SHAREABLE << AX_USER_DOMAIN_SHIFT;
+		dw_pcie_writel_dbi(pci, PCIE_ARUSER_REG, reg);
 
-	reg = dw_pcie_readl_dbi(pci, PCIE_AWUSER_REG);
-	reg &= ~(AX_USER_DOMAIN_MASK << AX_USER_DOMAIN_SHIFT);
-	reg |= DOMAIN_OUTER_SHAREABLE << AX_USER_DOMAIN_SHIFT;
-	dw_pcie_writel_dbi(pci, PCIE_AWUSER_REG, reg);
+		reg = dw_pcie_readl_dbi(pci, PCIE_AWUSER_REG);
+		reg &= ~(AX_USER_DOMAIN_MASK << AX_USER_DOMAIN_SHIFT);
+		reg |= DOMAIN_OUTER_SHAREABLE << AX_USER_DOMAIN_SHIFT;
+		dw_pcie_writel_dbi(pci, PCIE_AWUSER_REG, reg);
+	}
 
 	/* Enable INT A-D interrupts */
-	reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG);
-	reg |= PCIE_INT_A_ASSERT_MASK | PCIE_INT_B_ASSERT_MASK |
-	       PCIE_INT_C_ASSERT_MASK | PCIE_INT_D_ASSERT_MASK;
-	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG, reg);
+	if (pcie->pcie_type == ARMADA8K_PCIE_TYPE_AC5) {
+		reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_MASK2_REG);
+		reg |= PCIE_INT_A_ASSERT_MASK_AC5 | PCIE_INT_B_ASSERT_MASK_AC5 |
+		       PCIE_INT_C_ASSERT_MASK_AC5 | PCIE_INT_D_ASSERT_MASK_AC5;
+		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_MASK2_REG, reg);
+	} else {
+		reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG);
+		reg |= PCIE_INT_A_ASSERT_MASK | PCIE_INT_B_ASSERT_MASK |
+		       PCIE_INT_C_ASSERT_MASK | PCIE_INT_D_ASSERT_MASK;
+		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG, reg);
+	}
 
 	return 0;
 }
@@ -258,9 +275,59 @@ static int armada8k_add_pcie_port(struct armada8k_pcie *pcie,
 	return 0;
 }
 
-static const struct dw_pcie_ops dw_pcie_ops = {
+static u32 ac5_xlate_dbi_reg(u32 reg)
+{
+	/* Handle AC5 ATU access */
+	if ((reg & ~0xfffff) == PCIE_ATU_ACCESS_MASK_AC5) {
+		reg &= 0xfffff;
+		/* ATU registers offset is 0xC00 + 0x200 * n,
+		 * from RFU registers.
+		 */
+		reg = 0xc000 | (0x200 * (reg >> 9)) | (reg & 0xff);
+	} else if ((reg & 0xfffff000) == PCIE_VENDOR_REGS_OFFSET) {
+		/* PCIe RFU registers in A8K are at offset 0x8000 from base
+		 * (0xf2600000) while in AC5 offset is 0x10000 from base
+		 * (0x800a0000) therefore need the addition of 0x8000.
+		 */
+		reg += PCIE_VENDOR_REGS_OFFSET;
+	}
+
+	return reg;
+}
+
+static u32 ac5_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base,
+			     u32 reg, size_t size)
+{
+	u32 val;
+
+	dw_pcie_read(base + ac5_xlate_dbi_reg(reg), size, &val);
+	return val;
+}
+
+static void ac5_pcie_write_dbi(struct dw_pcie *pci, void __iomem *base,
+			       u32 reg, size_t size, u32 val)
+{
+	dw_pcie_write(base + ac5_xlate_dbi_reg(reg), size, val);
+}
+
+static const struct dw_pcie_ops armada8k_dw_pcie_ops = {
+	.link_up = armada8k_pcie_link_up,
+};
+
+static const struct dw_pcie_ops ac5_dw_pcie_ops = {
 	.link_up = armada8k_pcie_link_up,
-	.start_link = armada8k_pcie_start_link,
+	.read_dbi = ac5_pcie_read_dbi,
+	.write_dbi = ac5_pcie_write_dbi,
+};
+
+static const struct armada8k_pcie_of_data a8k_pcie_of_data = {
+	.pcie_type = ARMADA8K_PCIE_TYPE_A8K,
+	.pcie_ops = &armada8k_dw_pcie_ops,
+};
+
+static const struct armada8k_pcie_of_data ac5_pcie_of_data = {
+	.pcie_type = ARMADA8K_PCIE_TYPE_AC5,
+	.pcie_ops = &ac5_dw_pcie_ops,
 };
 
 static int armada8k_pcie_probe(struct platform_device *pdev)
@@ -268,9 +335,15 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
 	struct dw_pcie *pci;
 	struct armada8k_pcie *pcie;
 	struct device *dev = &pdev->dev;
+	const struct armada8k_pcie_of_data *data;
 	struct resource *base;
 	int ret;
 
+	data = of_device_get_match_data(dev);
+	if (!data)
+		return -EINVAL;
+
+
 	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
 	if (!pcie)
 		return -ENOMEM;
@@ -279,9 +352,10 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
 	if (!pci)
 		return -ENOMEM;
 
+	pci->ops = data->pcie_ops;
 	pci->dev = dev;
-	pci->ops = &dw_pcie_ops;
 
+	pcie->pcie_type = data->pcie_type;
 	pcie->pci = pci;
 
 	pcie->clk = devm_clk_get(dev, NULL);
@@ -334,7 +408,14 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id armada8k_pcie_of_match[] = {
-	{ .compatible = "marvell,armada8k-pcie", },
+	{
+		.compatible = "marvell,armada8k-pcie",
+		.data = &a8k_pcie_of_data,
+	},
+	{
+		.compatible = "marvell,ac5-pcie",
+		.data = &ac5_pcie_of_data,
+	},
 	{},
 };
 
-- 
2.25.1

[PATCH v2 3/3] PCI: armada8k: Add MSI support for AC5 SoC

[Vadym Kochan]

From: Yuval Shaia <yshaia@marvell.com>

AC5 requires different handling for MSI as with armada8k.
Fix it by:

1. Enabling the relevant bits in init phase
2. Dispatch virtual IRQ handlers when MSI interrupts are received

Also enable/disable PCIE_APP_LTSSM for AC5.

Signed-off-by: Yuval Shaia <yshaia@marvell.com>
Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
---
v2:
   1) fix W1 warnings which caused by unused leftover code

   2) fix type in "requieres" word in the description

 drivers/pci/controller/dwc/pcie-armada8k.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-armada8k.c b/drivers/pci/controller/dwc/pcie-armada8k.c
index bbe9a1750d0d..7e02eddaeac0 100644
--- a/drivers/pci/controller/dwc/pcie-armada8k.c
+++ b/drivers/pci/controller/dwc/pcie-armada8k.c
@@ -50,6 +50,7 @@ struct armada8k_pcie_of_data {
 
 #define PCIE_GLOBAL_CONTROL_REG		(PCIE_VENDOR_REGS_OFFSET + 0x0)
 #define PCIE_APP_LTSSM_EN		BIT(2)
+#define PCIE_APP_LTSSM_EN_AC5		BIT(24)
 #define PCIE_DEVICE_TYPE_SHIFT		4
 #define PCIE_DEVICE_TYPE_MASK		0xF
 #define PCIE_DEVICE_TYPE_RC		0x4 /* Root complex */
@@ -69,6 +70,7 @@ struct armada8k_pcie_of_data {
 #define PCIE_INT_B_ASSERT_MASK_AC5	BIT(13)
 #define PCIE_INT_C_ASSERT_MASK_AC5	BIT(14)
 #define PCIE_INT_D_ASSERT_MASK_AC5	BIT(15)
+#define PCIE_MSI_MASK_AC5		BIT(11)
 
 #define PCIE_ATU_ACCESS_MASK_AC5	GENMASK(21, 20)
 
@@ -172,6 +174,16 @@ static int armada8k_pcie_link_up(struct dw_pcie *pci)
 	return 0;
 }
 
+static void ac5_pcie_msi_init(struct dw_pcie *pci)
+{
+	u32 val;
+
+	/* Set MSI bit in interrupt mask */
+	val = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG);
+	val |= PCIE_MSI_MASK_AC5;
+	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG, val);
+}
+
 static int armada8k_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	u32 reg;
@@ -181,7 +193,10 @@ static int armada8k_pcie_host_init(struct dw_pcie_rp *pp)
 	if (!dw_pcie_link_up(pci)) {
 		/* Disable LTSSM state machine to enable configuration */
 		reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_CONTROL_REG);
-		reg &= ~(PCIE_APP_LTSSM_EN);
+		if (pcie->pcie_type == ARMADA8K_PCIE_TYPE_AC5)
+			reg &= ~(PCIE_APP_LTSSM_EN_AC5);
+		else
+			reg &= ~(PCIE_APP_LTSSM_EN);
 		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
 	}
 
@@ -221,6 +236,9 @@ static int armada8k_pcie_host_init(struct dw_pcie_rp *pp)
 		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_MASK1_REG, reg);
 	}
 
+	if (IS_ENABLED(CONFIG_PCI_MSI) && (pcie->pcie_type == ARMADA8K_PCIE_TYPE_AC5))
+		ac5_pcie_msi_init(pci);
+
 	return 0;
 }
 
@@ -237,6 +255,8 @@ static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
 	 */
 	val = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_CAUSE1_REG);
 	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_CAUSE1_REG, val);
+	if ((PCIE_MSI_MASK_AC5 & val) && (pcie->pcie_type == ARMADA8K_PCIE_TYPE_AC5))
+		dw_handle_msi_irq(&pci->pp);
 
 	return IRQ_HANDLED;
 }
-- 
2.25.1

Re: [PATCH v2 1/3] dt-bindings: PCI: armada8k: Add compatible string for AC5 SoC

[Krzysztof Kozlowski]

On 24/11/2022 14:58, Vadym Kochan wrote:
> AC5 SoC has armada8k PCIe IP so add compatible string for it.
> 
> Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
> ---
> v2: no changes

Not correct... I wasted some time looking for v1. This is a new patch.


Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v2 2/3] PCI: armada8k: Add AC5 SoC support

[Thomas Petazzoni]

Hello,

On Thu, 24 Nov 2022 15:58:27 +0200
Vadym Kochan <vadym.kochan@plvision.eu> wrote:


> -static int armada8k_pcie_start_link(struct dw_pcie *pci)
> -{
> -	u32 reg;
> -
> -	/* Start LTSSM */
> -	reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_CONTROL_REG);
> -	reg |= PCIE_APP_LTSSM_EN;
> -	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
> -
> -	return 0;
> -}

So this code is going away, but I don't see it being re-added anywhere.
I don't think anything in the code you are adding that sets the
LTSSM_EN bit in PCIE_GLOBAL_CONTROL_REG. Am I missing something?

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com

Re: [PATCH v2 2/3] PCI: armada8k: Add AC5 SoC support

[Vadym Kochan]

Hi Thomas,

> On Thu, 24 Nov 2022 15:58:27 +0200
> Vadym Kochan <vadym.kochan@plvision.eu> wrote:
>
>> -static int armada8k_pcie_start_link(struct dw_pcie *pci)
>> -{
>> -     u32 reg;
>> -
>> -     /* Start LTSSM */
>> -     reg = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_CONTROL_REG);
>> -     reg |= PCIE_APP_LTSSM_EN;
>> -     dw_pcie_writel_dbi(pci, PCIE_GLOBAL_CONTROL_REG, reg);
>> -
>> -     return 0;
>> -}
>
>So this code is going away, but I don't see it being re-added anywhere.
>I don't think anything in the code you are adding that sets the
>LTSSM_EN bit in PCIE_GLOBAL_CONTROL_REG. Am I missing something?
>
>Thomas
>--
>Thomas Petazzoni, co-owner and CEO, Bootlin
>Embedded Linux and Kernel engineering and training
>https://bootlin.com

There is a reply from the Marvell:

[quote]
this is not needed, as by the time Linux is loaded, link has already been established (by boot loaders)

So this code is not needed.
[/quote]

Thanks,

Re: [PATCH v2 2/3] PCI: armada8k: Add AC5 SoC support

[Thomas Petazzoni]

Hello!

On Fri, 25 Nov 2022 08:43:06 +0000
Vadym Kochan <vadym.kochan@plvision.eu> wrote:

> [quote]
> this is not needed, as by the time Linux is loaded, link has already been established (by boot loaders)
> 
> So this code is not needed.
> [/quote]

Not ideal to rely on the bootloader for this sort of initialization,
and if we want to do this change, perhaps it should be done in another
patch.

But again, the fact that "it works for Marvell because their vendor
U-Boot does the right thing prior to loading Linux" is not really a
very solid argument to drop kernel code :-/

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com