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SubjectRe: [PATCH v2 2/2] PCI: qcom: Restrict pci transactions after pci suspend
On Wed, Jun 29, 2022 at 03:03:34PM +0530, Krishna chaitanya chundru wrote:
> If the endpoint device state is D0 and irq's are not freed, then
> kernel try to mask interrupts by writing in to the vector
> table (for MSIX interrupts) and config space (for MSI's).
>
> These transactions are initiated after clocks are getting disabled
> as part of PM suspend call. Due to it, these transactions are
> resulting in un-clocked access and eventual to crashes.
>
> So added a logic in qcom driver to restrict the unclocked access.
> And updated the logic to check the link state before masking
> or unmasking the interrupts.
>

No other PCI driver is doing the DBI access restriction. So this makes me feel
that the fix is somewhere else.

I'll dig into it and come back.

Thanks,
Mani

> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> ---
> drivers/pci/controller/dwc/pcie-designware-host.c | 14 +++++++--
> drivers/pci/controller/dwc/pcie-qcom.c | 35 +++++++++++++++++++++--
> 2 files changed, 45 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 2fa86f3..2a46b40 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -29,13 +29,23 @@ static void dw_msi_ack_irq(struct irq_data *d)
>
> static void dw_msi_mask_irq(struct irq_data *d)
> {
> - pci_msi_mask_irq(d);
> + struct pcie_port *pp = irq_data_get_irq_chip_data(d->parent_data);
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +
> + if (dw_pcie_link_up(pci))
> + pci_msi_mask_irq(d);
> +
> irq_chip_mask_parent(d);
> }
>
> static void dw_msi_unmask_irq(struct irq_data *d)
> {
> - pci_msi_unmask_irq(d);
> + struct pcie_port *pp = irq_data_get_irq_chip_data(d->parent_data);
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +
> + if (dw_pcie_link_up(pci))
> + pci_msi_unmask_irq(d);
> +
> irq_chip_unmask_parent(d);
> }
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 8e9ef37..227bc24a 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -1331,12 +1331,41 @@ static int qcom_pcie_disable_clks_2_7_0(struct qcom_pcie *pcie)
> return 0;
> }
>
> +static u32 qcom_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base,
> + u32 reg, size_t size)
> +{
> + struct qcom_pcie *pcie = to_qcom_pcie(pci);
> + u32 val;
> +
> + if (pcie->is_suspended)
> + return PCIBIOS_BAD_REGISTER_NUMBER;
> +
> + dw_pcie_read(base + reg, size, &val);
> + return val;
> +}
> +
> +static void qcom_pcie_write_dbi(struct dw_pcie *pci, void __iomem *base,
> + u32 reg, size_t size, u32 val)
> +{
> + struct qcom_pcie *pcie = to_qcom_pcie(pci);
> +
> + if (pcie->is_suspended)
> + return;
> +
> + dw_pcie_write(base + reg, size, val);
> +}
>
> static int qcom_pcie_link_up(struct dw_pcie *pci)
> {
> - u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> - u16 val = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
> + struct qcom_pcie *pcie = to_qcom_pcie(pci);
> + u16 offset;
> + u16 val;
> +
> + if (pcie->is_suspended)
> + return false;
>
> + offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> + val = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
> return !!(val & PCI_EXP_LNKSTA_DLLLA);
> }
>
> @@ -1580,6 +1609,8 @@ static const struct qcom_pcie_cfg sc7280_cfg = {
> static const struct dw_pcie_ops dw_pcie_ops = {
> .link_up = qcom_pcie_link_up,
> .start_link = qcom_pcie_start_link,
> + .read_dbi = qcom_pcie_read_dbi,
> + .write_dbi = qcom_pcie_write_dbi,
> };
>
> static int qcom_pcie_probe(struct platform_device *pdev)
> --
> 2.7.4
>

--
மணிவண்ணன் சதாசிவம்

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