[PATCH v2 2/4] PCI: tegra194: Remove unnecessary L1SS disable code

Bjorn Helgaas
2025-11-18T21:43:37Z

From: Bjorn Helgaas <bhelgaas@google.com>

The DWC core clears the L1 Substates Supported bits unless the driver sets
the "dw_pcie.l1ss_support" flag.

The tegra194 init_host_aspm() sets "dw_pcie.l1ss_support" if the platform
has the "supports-clkreq" DT property. If "supports-clkreq" is absent,
"dw_pcie.l1ss_support" is not set, and the DWC core will clear the L1
Substates Supported bits.

The tegra194 code to clear the L1 Substates Supported bits is unnecessary,
so remove it.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/controller/dwc/pcie-tegra194.c | 45 +++-------------------
1 file changed, 5 insertions(+), 40 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 3934757baa30..0ddeef70726d 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -260,7 +260,6 @@ struct tegra_pcie_dw {
u32 msi_ctrl_int;
u32 num_lanes;
u32 cid;
- u32 cfg_link_cap_l1sub;
u32 ras_des_cap;
u32 pcie_cap_base;
u32 aspm_cmrt;
@@ -475,8 +474,7 @@ static irqreturn_t tegra_pcie_ep_irq_thread(int irq, void *arg)
return IRQ_HANDLED;

/* If EP doesn't advertise L1SS, just return */
- val = dw_pcie_readl_dbi(pci, pcie->cfg_link_cap_l1sub);
- if (!(val & (PCI_L1SS_CAP_ASPM_L1_1 | PCI_L1SS_CAP_ASPM_L1_2)))
+ if (!pci->l1ss_support)
return IRQ_HANDLED;

/* Check if BME is set to '1' */
@@ -608,24 +606,6 @@ static struct pci_ops tegra_pci_ops = {
};

#if defined(CONFIG_PCIEASPM)
-static void disable_aspm_l11(struct tegra_pcie_dw *pcie)
-{
- u32 val;
-
- val = dw_pcie_readl_dbi(&pcie->pci, pcie->cfg_link_cap_l1sub);
- val &= ~PCI_L1SS_CAP_ASPM_L1_1;
- dw_pcie_writel_dbi(&pcie->pci, pcie->cfg_link_cap_l1sub, val);
-}
-
-static void disable_aspm_l12(struct tegra_pcie_dw *pcie)
-{
- u32 val;
-
- val = dw_pcie_readl_dbi(&pcie->pci, pcie->cfg_link_cap_l1sub);
- val &= ~PCI_L1SS_CAP_ASPM_L1_2;
- dw_pcie_writel_dbi(&pcie->pci, pcie->cfg_link_cap_l1sub, val);
-}
-
static inline u32 event_counter_prog(struct tegra_pcie_dw *pcie, u32 event)
{
u32 val;
@@ -682,10 +662,9 @@ static int aspm_state_cnt(struct seq_file *s, void *data)
static void init_host_aspm(struct tegra_pcie_dw *pcie)
{
struct dw_pcie *pci = &pcie->pci;
- u32 val;
+ u32 l1ss, val;

- val = dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_L1SS);
- pcie->cfg_link_cap_l1sub = val + PCI_L1SS_CAP;
+ l1ss = dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_L1SS);

pcie->ras_des_cap = dw_pcie_find_ext_capability(&pcie->pci,
PCI_EXT_CAP_ID_VNDR);
@@ -697,11 +676,11 @@ static void init_host_aspm(struct tegra_pcie_dw *pcie)
PCIE_RAS_DES_EVENT_COUNTER_CONTROL, val);

/* Program T_cmrt and T_pwr_on values */
- val = dw_pcie_readl_dbi(pci, pcie->cfg_link_cap_l1sub);
+ val = dw_pcie_readl_dbi(pci, l1ss + PCI_L1SS_CAP);
val &= ~(PCI_L1SS_CAP_CM_RESTORE_TIME | PCI_L1SS_CAP_P_PWR_ON_VALUE);
val |= (pcie->aspm_cmrt << 8);
val |= (pcie->aspm_pwr_on_t << 19);
- dw_pcie_writel_dbi(pci, pcie->cfg_link_cap_l1sub, val);
+ dw_pcie_writel_dbi(pci, l1ss + PCI_L1SS_CAP, val);

if (pcie->supports_clkreq)
pci->l1ss_support = true;
@@ -729,8 +708,6 @@ static void init_debugfs(struct tegra_pcie_dw *pcie)
aspm_state_cnt);
}
#else
-static inline void disable_aspm_l12(struct tegra_pcie_dw *pcie) { return; }
-static inline void disable_aspm_l11(struct tegra_pcie_dw *pcie) { return; }
static inline void init_host_aspm(struct tegra_pcie_dw *pcie) { return; }
static inline void init_debugfs(struct tegra_pcie_dw *pcie) { return; }
#endif
@@ -934,12 +911,6 @@ static int tegra_pcie_dw_host_init(struct dw_pcie_rp *pp)

init_host_aspm(pcie);

- /* Disable ASPM-L1SS advertisement if there is no CLKREQ routing */
- if (!pcie->supports_clkreq) {
- disable_aspm_l11(pcie);
- disable_aspm_l12(pcie);
- }
-
if (!pcie->of_data->has_l1ss_exit_fix) {
val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
val &= ~GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL;
@@ -1874,12 +1845,6 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)

init_host_aspm(pcie);

- /* Disable ASPM-L1SS advertisement if there is no CLKREQ routing */
- if (!pcie->supports_clkreq) {
- disable_aspm_l11(pcie);
- disable_aspm_l12(pcie);
- }
-
if (!pcie->of_data->has_l1ss_exit_fix) {
val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
val &= ~GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL;
--
2.43.0