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Date: Thu, 1 Jun 2017 11:11:24 -0700
From: Ray Jui <ray.jui@...adcom.com>
To: Oza Pawandeep <oza.oza@...adcom.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Ray Jui <rjui@...adcom.com>,
Scott Branden <sbranden@...adcom.com>,
Jon Mason <jonmason@...adcom.com>,
bcm-kernel-feedback-list@...adcom.com,
Andy Gospodarek <gospo@...adcom.com>,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
Oza Pawandeep <oza.pawandeep@...il.com>
Subject: Re: [PATCH 2/2] PCI: iproc: add device shutdown for PCI RC
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@...adcom.com>
> Reviewed-by: Ray Jui <ray.jui@...adcom.com>
> Reviewed-by: Scott Branden <scott.branden@...adcom.com>
>
> 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);
>
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