Some devices (due to e.g. bad PCIe signal integrity) require to run
with forced GEN1 speed on PCIe bus.
This patch changes the speed explicitly on dra7 based devices when
proper device tree attribute is defined for the PCIe controller.
Signed-off-by: Lukasz Majewski <lukma@xxxxxxx>
---
Patch applies on newest origin/master
SHA1: f4d3935e4f4884ba80561db5549394afb8eef8f7
Tested at AM5728
---
Documentation/devicetree/bindings/pci/ti-pci.txt | 1 +
drivers/pci/host/pci-dra7xx.c | 23 +++++++++++++++++++++++
drivers/pci/host/pcie-designware.h | 1 +
3 files changed, 25 insertions(+)
diff --git a/Documentation/devicetree/bindings/pci/ti-pci.txt b/Documentation/devicetree/bindings/pci/ti-pci.txt
index 60e2516..9f97409 100644
--- a/Documentation/devicetree/bindings/pci/ti-pci.txt
+++ b/Documentation/devicetree/bindings/pci/ti-pci.txt
@@ -25,6 +25,7 @@ PCIe Designware Controller
Optional Property:
- gpios : Should be added if a gpio line is required to drive PERST# line
+ - to,pcie-is-gen1: Indicates that forced gen1 port operation is needed.
Example:
axi {
diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
index 9595fad..eec5fae 100644
--- a/drivers/pci/host/pci-dra7xx.c
+++ b/drivers/pci/host/pci-dra7xx.c
@@ -63,6 +63,13 @@
#define LINK_UP BIT(16)
#define DRA7XX_CPU_TO_BUS_ADDR 0x0FFFFFFF
+#define PCIECTRL_EP_DBICS_LNK_CAP 0x007C
+#define MAX_LINK_SPEEDS_MASK GENMASK(3, 0)
+#define MAX_LINK_SPEEDS_GEN1 BIT(0)
+
+#define PCIECTRL_PL_WIDTH_SPEED_CTL 0x080C
+#define CFG_DIRECTED_SPEED_CHANGE BIT(17)
+
struct dra7xx_pcie {
struct pcie_port pp;
void __iomem *base; /* DT ti_conf */
@@ -270,6 +277,7 @@ static int __init dra7xx_add_pcie_port(struct dra7xx_pcie *dra7xx,
struct pcie_port *pp = &dra7xx->pp;
struct device *dev = pp->dev;
struct resource *res;
+ u32 val;
pp->irq = platform_get_irq(pdev, 1);
if (pp->irq < 0) {
@@ -296,6 +304,18 @@ static int __init dra7xx_add_pcie_port(struct dra7xx_pcie *dra7xx,
if (!pp->dbi_base)
return -ENOMEM;
+ if (pp->is_gen1) {
+ dev_info(dev, "GEN1 forced\n");
+
+ val = readl(pp->dbi_base + PCIECTRL_EP_DBICS_LNK_CAP);
+ set_mask_bits(&val, MAX_LINK_SPEEDS_MASK, MAX_LINK_SPEEDS_GEN1);
+ writel(val, pp->dbi_base + PCIECTRL_EP_DBICS_LNK_CAP);
+
+ val = readl(pp->dbi_base + PCIECTRL_PL_WIDTH_SPEED_CTL);
+ val &= ~CFG_DIRECTED_SPEED_CHANGE;
+ writel(val, pp->dbi_base + PCIECTRL_PL_WIDTH_SPEED_CTL);
+ }
+
ret = dw_pcie_host_init(pp);
if (ret) {
dev_err(dev, "failed to initialize host\n");
@@ -404,6 +424,9 @@ static int __init dra7xx_pcie_probe(struct platform_device *pdev)
goto err_gpio;
}
+ if (of_property_read_bool(np, "ti,pcie-is-gen1"))
+ pp->is_gen1 = true;
+
reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_DEVICE_CMD);
reg &= ~LTSSM_EN;
dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_DEVICE_CMD, reg);
diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
index a567ea2..2fb0b18 100644
--- a/drivers/pci/host/pcie-designware.h
+++ b/drivers/pci/host/pcie-designware.h
@@ -50,6 +50,7 @@ struct pcie_port {
struct irq_domain *irq_domain;
unsigned long msi_data;
u8 iatu_unroll_enabled;
+ u8 is_gen1;
DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
};
--
2.1.4
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