Subject: Re: [PATCH v8 03/10] PCI: dwc: ep: Introduce dw_pcie_ep_cleanup() API for drivers supporting PERST#

From: Niklas Cassel <[email-masked]>
Date: Thu, 29 Feb 2024 13:40:29 +0100

On Sat, Feb 24, 2024 at 12:24:09PM +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 <[email-masked]>
> Closes: https://lore.kernel.org/linux-pci/ZWYmX8Y%2F7Q9WMxES@x1-carbon
> Signed-off-by: Manivannan Sadhasivam <[email-masked]>
> ---
>  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);

Hello Mani,

In this message:
https://lore.kernel.org/linux-pci/20240130062938.GB32821@thinkpad/

You mentioned that you were going to clean up the BARs.
(Like I wrote in that thread, I really think that we should merge a fix for
the broken "do we have a saved value from find_first_zero_bit() in the array",
by using a "if (!saved_value[bar])", when find_first_zero_bit() returns zero.)

However, regardless of that, I do not see that this series (neither
dw_pcie_ep_cleanup(), nor dw_pcie_ep_linkdown()), calls any function which
will clean up the BARs.

Since e.g. qcom-ep.c does a reset_control_assert() during perst
assert/deassert, which should clear sticky registers, I think that
you should let dw_pcie_ep_cleanup() clean up the BARs using
dw_pcie_ep_clear_bar().

Kind regards,
Niklas

> +}
> +EXPORT_SYMBOL_GPL(dw_pcie_ep_cleanup);
> +
> +void dw_pcie_ep_deinit(struct dw_pcie_ep *ep)
> +{
> +	struct pci_epc *epc = ep->epc;
> +
> +	dw_pcie_ep_cleanup(ep);
>  
>  	pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
>  			      epc->mem->window.page_size);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 61465203bb60..351d2fe3ea4d 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -672,6 +672,7 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep);
>  int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep);
>  void dw_pcie_ep_init_notify(struct dw_pcie_ep *ep);
>  void dw_pcie_ep_deinit(struct dw_pcie_ep *ep);
> +void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep);
>  int dw_pcie_ep_raise_intx_irq(struct dw_pcie_ep *ep, u8 func_no);
>  int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
>  			     u8 interrupt_num);
> @@ -705,6 +706,10 @@ static inline void dw_pcie_ep_deinit(struct dw_pcie_ep *ep)
>  {
>  }
>  
> +static inline void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep)
> +{
> +}
> +
>  static inline int dw_pcie_ep_raise_intx_irq(struct dw_pcie_ep *ep, u8 func_no)
>  {
>  	return 0;
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> index 36e5e80cd22f..59b1c0110288 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -507,6 +507,7 @@ static void qcom_pcie_perst_assert(struct dw_pcie *pci)
>  		return;
>  	}
>  
> +	dw_pcie_ep_cleanup(&pci->ep);
>  	qcom_pcie_disable_resources(pcie_ep);
>  	pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED;
>  }
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 7afa9e9aabe2..68bfeed3429b 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -1715,6 +1715,8 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie)
>  	if (ret)
>  		dev_err(pcie->dev, "Failed to go Detect state: %d\n", ret);
>  
> +	dw_pcie_ep_cleanup(&pcie->pci.ep);
> +
>  	reset_control_assert(pcie->core_rst);
>  
>  	tegra_pcie_disable_phy(pcie);
> 
> -- 
> 2.25.1
>