[PATCH] PCI/sophgo: Avoid L0s and L1 on Sophgo 2044 PCIe Root Ports

[Inochi Amaoto <inochiama@gmail.com>]

Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
states for devicetree platforms") force enable ASPM on all device tree
platform, the SG2044 root port breaks as it advertises L0s and L1
capabilities without supporting it.

Mask the L0s and L1 Support advertised in Link Capabilities
in the LINKCAP register SG2044 Root Ports, so the framework
won't try to enable those states.

Fixes: 3309df45e6b5 ("riscv: dts: sophgo: sg2044: add PCIe device support for SG2044")
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Tested-by: Han Gao <gaohan@iscas.ac.cn>
---
Change from original patch:
1. use driver to mask the ASPM advertisement

Separate from the folloing patch
- https://lore.kernel.org/all/20251225100530.1301625-1-inochiama@gmail.com
---
 drivers/pci/controller/dwc/pcie-sophgo.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-sophgo.c b/drivers/pci/controller/dwc/pcie-sophgo.c
index ad4baaa34ffa..044088898819 100644
--- a/drivers/pci/controller/dwc/pcie-sophgo.c
+++ b/drivers/pci/controller/dwc/pcie-sophgo.c
@@ -161,6 +161,22 @@ static void sophgo_pcie_msi_enable(struct dw_pcie_rp *pp)
 	raw_spin_unlock_irqrestore(&pp->lock, flags);
 }

+static void sophgo_pcie_disable_l0s_l1(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	u32 offset, val;
+
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+
+	dw_pcie_dbi_ro_wr_en(pci);
+
+	val = dw_pcie_readl_dbi(pci, PCI_EXP_LNKCAP + offset);
+	val &= ~(PCI_EXP_LNKCAP_ASPM_L0S | PCI_EXP_LNKCAP_ASPM_L1);
+	dw_pcie_writel_dbi(pci, PCI_EXP_LNKCAP + offset, val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
+}
+
 static int sophgo_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	int irq;
@@ -171,6 +187,8 @@ static int sophgo_pcie_host_init(struct dw_pcie_rp *pp)

 	irq_set_chained_handler_and_data(irq, sophgo_pcie_intx_handler, pp);

+	sophgo_pcie_disable_l0s_l1(pp);
+
 	sophgo_pcie_msi_enable(pp);

 	return 0;
--
2.52.0