Re: [PATCH v9 03/10] PCI: dwc: ep: Introduce dw_pcie_ep_cleanup() API for drivers supporting PERST#

Niklas Cassel
2024-03-07T20:14:21Z

On Mon, Mar 04, 2024 at 02:52:15PM +0530, Manivannan Sadhasivam wrote:
> For DWC glue drivers supporting PERST# (currently Qcom and Tegra194), some
> of the DWC resources like eDMA should be cleaned up during the PERST#
> assert time.
>
> So let's introduce a dw_pcie_ep_cleanup() API that could be called by these
> drivers to cleanup the DWC specific resources. Currently, it just removes
> eDMA.
>
> Reported-by: Niklas Cassel <cassel@kernel.org>
> Closes: https://lore.kernel.org/linux-pci/ZWYmX8Y%2F7Q9WMxES@x1-carbon
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> drivers/pci/controller/dwc/pcie-designware-ep.c | 11 +++++++++--
> drivers/pci/controller/dwc/pcie-designware.h | 5 +++++
> drivers/pci/controller/dwc/pcie-qcom-ep.c | 1 +
> drivers/pci/controller/dwc/pcie-tegra194.c | 2 ++
> 4 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 2b11290aab4c..1205bfba8310 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -564,12 +564,19 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
> return 0;
> }
>
> -void dw_pcie_ep_deinit(struct dw_pcie_ep *ep)
> +void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep)
> {
> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> - struct pci_epc *epc = ep->epc;
>
> dw_pcie_edma_remove(pci);
> +}
> +EXPORT_SYMBOL_GPL(dw_pcie_ep_cleanup);

Since you are not clearing the iATU bits in ep->ib_window_map and
ep->bar_to_atu, this will "leak" resources, so depending on how many
inbound iATUs the platform has, by simply the RC toggling PERST,
will cause an error when calling set_bar() after dw_pcie_ep_init_notify().

However, because you have said that you will address this in a follow up
series:
Reviewed-by: Niklas Cassel <cassel@kernel.org>