[PATCH 10/11] PCI: qcom-ep: Rework {start/stop}_link() callbacks implementation

Manivannan Sadhasivam
2024-03-14T15:24:52Z

DWC specific start_link() and stop_link() callbacks are supposed to start
and stop the link training of the PCIe bus. But the current implementation
of this driver enables/disables the PERST# IRQ.

Even though this is not causing any issues, this creates inconsistency
among the controller drivers. So for the sake of consistency, let's just
start/stop the link training in these callbacks.

Also, PERST# IRQ is now enabled from the start itself, thus allowing the
controller driver to initialize the registers when PERST# gets deasserted
without waiting for the user intervention though configfs.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
drivers/pci/controller/dwc/pcie-qcom-ep.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 811f250e967a..653e4ace0a07 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -122,6 +122,9 @@
/* PARF_CFG_BITS register fields */
#define PARF_CFG_BITS_REQ_EXIT_L1SS_MSI_LTR_EN BIT(1)

+/* PARF_LTSSM register fields */
+#define LTSSM_EN BIT(8)
+
/* ELBI registers */
#define ELBI_SYS_STTS 0x08
#define ELBI_CS2_ENABLE 0xa4
@@ -250,8 +253,12 @@ static int qcom_pcie_dw_link_up(struct dw_pcie *pci)
static int qcom_pcie_dw_start_link(struct dw_pcie *pci)
{
struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+ u32 val;

- enable_irq(pcie_ep->perst_irq);
+ /* Enable LTSSM */
+ val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
+ val |= LTSSM_EN;
+ writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);

return 0;
}
@@ -259,8 +266,12 @@ static int qcom_pcie_dw_start_link(struct dw_pcie *pci)
static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
{
struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
+ u32 val;

- disable_irq(pcie_ep->perst_irq);
+ /* Disable LTSSM */
+ val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
+ val &= ~LTSSM_EN;
+ writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
}

static void qcom_pcie_dw_write_dbi2(struct dw_pcie *pci, void __iomem *base,
@@ -484,11 +495,6 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)

dw_pcie_ep_init_notify(&pcie_ep->pci.ep);

- /* Enable LTSSM */
- val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
- val |= BIT(8);
- writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
-
return 0;

err_disable_resources:
@@ -707,7 +713,6 @@ static int qcom_pcie_ep_enable_irq_resources(struct platform_device *pdev,
}

pcie_ep->perst_irq = gpiod_to_irq(pcie_ep->reset);
- irq_set_status_flags(pcie_ep->perst_irq, IRQ_NOAUTOEN);
ret = devm_request_threaded_irq(&pdev->dev, pcie_ep->perst_irq, NULL,
qcom_pcie_ep_perst_irq_thread,
IRQF_TRIGGER_HIGH | IRQF_ONESHOT,

--
2.25.1