From b91c26c6a539e26261cbe280b9f48311663ce655 Mon Sep 17 00:00:00 2001 From: Oza Pawandeep Date: Mon, 28 Aug 2017 16:43:35 -0500 Subject: PCI: iproc: Add 500ms delay during device shutdown During soft reset (e.g., "reboot" from Linux) on some iProc-based SOCs, the LCPLL clock and PERST both go off simultaneously. This seems in accordance with the PCIe Card Electromechanical spec, r2.0, sec 2.2.3, which says the clock goes inactive after PERST# goes active, but doesn't specify how long the clock should be valid after PERST#. However, we have observed that with the iProc Stingray, some Intel NVMe endpoints, e.g., the P3700 400GB series, are not detected correctly upon the next boot sequence unless the clock remains valid for some time after PERST# is asserted. Delay 500ms after asserting PERST# before performing a reboot. The 500ms is experimentally determined. Signed-off-by: Oza Pawandeep [bhelgaas: changelog, add spec reference, fold in iproc_pcie_shutdown() export from Arnd Bergmann ] Signed-off-by: Bjorn Helgaas Reviewed-by: Ray Jui Reviewed-by: Scott Branden --- drivers/pci/host/pcie-iproc.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-) (limited to 'drivers/pci/host/pcie-iproc.c') diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c index 9a006cbc3021..fe2e5aaaff55 100644 --- a/drivers/pci/host/pcie-iproc.c +++ b/drivers/pci/host/pcie-iproc.c @@ -671,7 +671,7 @@ static struct pci_ops iproc_pcie_ops = { .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; @@ -683,20 +683,28 @@ static void iproc_pcie_reset(struct iproc_pcie *pcie) 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; } +EXPORT_SYMBOL_GPL(iproc_pcie_shutdown); static int iproc_pcie_check_link(struct iproc_pcie *pcie) { @@ -1379,7 +1387,8 @@ 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); -- cgit v1.2.3