Re: [PATCH 2/2] PCI: iproc: add device shutdown for PCI RC

[Ray Jui]

Hi Oza,

On 5/31/17 10:27 PM, Oza Pawandeep wrote:
> PERST# must be asserted around ~500ms before
> the reboot is applied.
> 
> During soft reset (e.g., "reboot" from Linux) on some iProc based SoCs
> LCPLL clock and PERST both goes off simultaneously.
> This will cause certain Endpoints Intel NVMe not get detected, upon
> next boot sequence.
> 
> This happens because; Endpoint is expecting the clock for some amount of
> time after PERST is asserted, which is not happening in our case
> (Compare to Intel X86 boards, will have clocks running).
> this cause NVMe to behave in undefined way.
> 
> Essentially clock will remain alive for 500ms with PERST# = 0
> before reboot.
> 
> This patch adds platform shutdown where it should be
> called in device_shutdown while reboot command is issued.
> 
> So in sequence first Endpoint Shutdown (e.g. nvme_shutdown)
> followed by RC shutdown is called, which issues safe PERST
> assertion.
> 
> Signed-off-by: Oza Pawandeep <oza.oza@xxxxxxxxxxxx>
> Reviewed-by: Ray Jui <ray.jui@xxxxxxxxxxxx>
> Reviewed-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
> 
> diff --git a/drivers/pci/host/pcie-iproc-platform.c b/drivers/pci/host/pcie-iproc-platform.c
> index 90d2bdd..9512960 100644
> --- a/drivers/pci/host/pcie-iproc-platform.c
> +++ b/drivers/pci/host/pcie-iproc-platform.c
> @@ -131,6 +131,13 @@ static int iproc_pcie_pltfm_remove(struct platform_device *pdev)
>  	return iproc_pcie_remove(pcie);
>  }
>  
> +static void iproc_pcie_pltfm_shutdown(struct platform_device *pdev)
> +{
> +	struct iproc_pcie *pcie = platform_get_drvdata(pdev);
> +
> +	iproc_pcie_shutdown(pcie);
> +}
> +
>  static struct platform_driver iproc_pcie_pltfm_driver = {
>  	.driver = {
>  		.name = "iproc-pcie",
> @@ -138,6 +145,7 @@ static int iproc_pcie_pltfm_remove(struct platform_device *pdev)
>  	},
>  	.probe = iproc_pcie_pltfm_probe,
>  	.remove = iproc_pcie_pltfm_remove,
> +	.shutdown = iproc_pcie_pltfm_shutdown,
>  };
>  module_platform_driver(iproc_pcie_pltfm_driver);
>  
> diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
> index 05a3647..e9afc63 100644
> --- a/drivers/pci/host/pcie-iproc.c
> +++ b/drivers/pci/host/pcie-iproc.c
> @@ -608,31 +608,38 @@ static int iproc_pcie_config_write32(struct pci_bus *bus, unsigned int devfn,
>  	.write = iproc_pcie_config_write32,
>  };
>  
> -static void iproc_pcie_reset(struct iproc_pcie *pcie)
> +static void iproc_pcie_perst_ctrl(struct iproc_pcie *pcie, bool assert)
>  {
>  	u32 val;
>  
>  	/*
> -	 * PAXC and the internal emulated endpoint device downstream should not
> -	 * be reset.  If firmware has been loaded on the endpoint device at an
> -	 * earlier boot stage, reset here causes issues.
> +	 * The internal emulated endpoints (such as PAXC) device downstream
> +	 * should not be reset. If firmware has been loaded on the endpoint
> +	 * device at an earlier boot stage, reset here causes issues.
>  	 */
>  	if (pcie->ep_is_internal)
>  		return;
>  
> -	/*
> -	 * Select perst_b signal as reset source. Put the device into reset,
> -	 * and then bring it out of reset
> -	 */
> -	val = iproc_pcie_read_reg(pcie, IPROC_PCIE_CLK_CTRL);
> -	val &= ~EP_PERST_SOURCE_SELECT & ~EP_MODE_SURVIVE_PERST &
> -		~RC_PCIE_RST_OUTPUT;
> -	iproc_pcie_write_reg(pcie, IPROC_PCIE_CLK_CTRL, val);
> -	udelay(250);
> -
> -	val |= RC_PCIE_RST_OUTPUT;
> -	iproc_pcie_write_reg(pcie, IPROC_PCIE_CLK_CTRL, val);
> -	msleep(100);
> +	if (assert) {
> +		val = iproc_pcie_read_reg(pcie, IPROC_PCIE_CLK_CTRL);
> +		val &= ~EP_PERST_SOURCE_SELECT & ~EP_MODE_SURVIVE_PERST &
> +			~RC_PCIE_RST_OUTPUT;
> +		iproc_pcie_write_reg(pcie, IPROC_PCIE_CLK_CTRL, val);
> +		udelay(250);
> +	} else {
> +		val = iproc_pcie_read_reg(pcie, IPROC_PCIE_CLK_CTRL);
> +		val |= RC_PCIE_RST_OUTPUT;
> +		iproc_pcie_write_reg(pcie, IPROC_PCIE_CLK_CTRL, val);
> +		msleep(100);
> +	}
> +}
> +
> +int iproc_pcie_shutdown(struct iproc_pcie *pcie)
> +{
> +	iproc_pcie_perst_ctrl(pcie, true);
> +	msleep(500);
> +
> +	return 0;
>  }

Please export the symbol here to fix the build issue detected by kbuild
test when the iProc PCIe platform driver is compiled as a kernel module.

>  
>  static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
> @@ -1310,7 +1317,8 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
>  		goto err_exit_phy;
>  	}
>  
> -	iproc_pcie_reset(pcie);
> +	iproc_pcie_perst_ctrl(pcie, true);
> +	iproc_pcie_perst_ctrl(pcie, false);
>  
>  	if (pcie->need_ob_cfg) {
>  		ret = iproc_pcie_map_ranges(pcie, res);
> diff --git a/drivers/pci/host/pcie-iproc.h b/drivers/pci/host/pcie-iproc.h
> index 0bbe2ea..a6b55ce 100644
> --- a/drivers/pci/host/pcie-iproc.h
> +++ b/drivers/pci/host/pcie-iproc.h
> @@ -110,6 +110,7 @@ struct iproc_pcie {
>  
>  int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res);
>  int iproc_pcie_remove(struct iproc_pcie *pcie);
> +int iproc_pcie_shutdown(struct iproc_pcie *pcie);
>  
>  #ifdef CONFIG_PCIE_IPROC_MSI
>  int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node);
>