linux-kernel - Re: [PATCH] PCI: dwc: Move forward the iATU detection process

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Message-ID: <21daa79d-cdb3-f31c-0fbf-5d653de02517@samsung.com>
Date:   Thu, 25 Mar 2021 10:24:28 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Zhiqiang Hou <Zhiqiang.Hou@....com>, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, lorenzo.pieralisi@....com
Cc:     robh@...nel.org, bhelgaas@...gle.com,
        gustavo.pimentel@...opsys.com, jingoohan1@...il.com,
        정재훈 <jh80.chung@...sung.com>
Subject: Re: [PATCH] PCI: dwc: Move forward the iATU detection process

Hi,

On 25.01.2021 05:48, Zhiqiang Hou wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou@....com>
>
> In the dw_pcie_ep_init(), it depends on the detected iATU region
> numbers to allocate the in/outbound window management bit map.
> It fails after the commit 281f1f99cf3a ("PCI: dwc: Detect number
> of iATU windows").
>
> So this patch move the iATU region detection into a new function,
> move forward the detection to the very beginning of functions
> dw_pcie_host_init() and dw_pcie_ep_init(). And also remove it
> from the dw_pcie_setup(), since it's more like a software
> perspective initialization step than hardware setup.
>
> Fixes: 281f1f99cf3a ("PCI: dwc: Detect number of iATU windows")
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>

This patch causes exynos-pcie to hang during the initialization. It 
looks that some resources are not enabled yet, so calling 
dw_pcie_iatu_detect() much earlier causes a hang. When I have some time, 
I will try to identify what is needed to call it properly.

> ---
>   drivers/pci/controller/dwc/pcie-designware-ep.c   |  2 ++
>   drivers/pci/controller/dwc/pcie-designware-host.c |  2 ++
>   drivers/pci/controller/dwc/pcie-designware.c      | 11 ++++++++---
>   drivers/pci/controller/dwc/pcie-designware.h      |  1 +
>   4 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index bcd1cd9ba8c8..fcf935bf6f5e 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -707,6 +707,8 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>   		}
>   	}
>   
> +	dw_pcie_iatu_detect(pci);
> +
>   	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
>   	if (!res)
>   		return -EINVAL;
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 8a84c005f32b..8eae817c138d 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -316,6 +316,8 @@ int dw_pcie_host_init(struct pcie_port *pp)
>   			return PTR_ERR(pci->dbi_base);
>   	}
>   
> +	dw_pcie_iatu_detect(pci);
> +
>   	bridge = devm_pci_alloc_host_bridge(dev, 0);
>   	if (!bridge)
>   		return -ENOMEM;
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 5b72a5448d2e..5b9bf02d918b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -654,11 +654,9 @@ static void dw_pcie_iatu_detect_regions(struct dw_pcie *pci)
>   	pci->num_ob_windows = ob;
>   }
>   
> -void dw_pcie_setup(struct dw_pcie *pci)
> +void dw_pcie_iatu_detect(struct dw_pcie *pci)
>   {
> -	u32 val;
>   	struct device *dev = pci->dev;
> -	struct device_node *np = dev->of_node;
>   	struct platform_device *pdev = to_platform_device(dev);
>   
>   	if (pci->version >= 0x480A || (!pci->version &&
> @@ -687,6 +685,13 @@ void dw_pcie_setup(struct dw_pcie *pci)
>   
>   	dev_info(pci->dev, "Detected iATU regions: %u outbound, %u inbound",
>   		 pci->num_ob_windows, pci->num_ib_windows);
> +}
> +
> +void dw_pcie_setup(struct dw_pcie *pci)
> +{
> +	u32 val;
> +	struct device *dev = pci->dev;
> +	struct device_node *np = dev->of_node;
>   
>   	if (pci->link_gen > 0)
>   		dw_pcie_link_set_max_speed(pci, pci->link_gen);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 5d979953800d..867369d4c4f7 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -305,6 +305,7 @@ int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
>   void dw_pcie_disable_atu(struct dw_pcie *pci, int index,
>   			 enum dw_pcie_region_type type);
>   void dw_pcie_setup(struct dw_pcie *pci);
> +void dw_pcie_iatu_detect(struct dw_pcie *pci);
>   
>   static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
>   {

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland