From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751353AbdBXGzO (ORCPT ); Fri, 24 Feb 2017 01:55:14 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:31874 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751115AbdBXGzH (ORCPT ); Fri, 24 Feb 2017 01:55:07 -0500 From: Yinghai Lu To: Bjorn Helgaas Cc: Ashok Raj , james puthukattukaran , Yinghai Lu , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Yinghai Lu Subject: [PATCH] PCI,pciehp: Skip not changed command write Date: Thu, 23 Feb 2017 22:54:49 -0800 Message-Id: <20170224065449.14997-1-yinghai@kernel.org> X-Mailer: git-send-email 2.8.3 X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Notice two systems with different cpu hve different print out when power on slots: First one: pciehp 0000:60:03.2:pcie004: pciehp_green_led_on: SLOTCTRL a8 write cmd 100 pciehp 0000:60:03.2:pcie004: pciehp_set_attention_status: SLOTCTRL a8 write cmd c0 pciehp 0000:60:03.2:pcie004: pending interrupts 0x0010 from Slot Status Second one: pciehp 0000:73:00.0:pcie004: pciehp_green_led_on: SLOTCTRL a8 write cmd 100 pciehp 0000:73:00.0:pcie004: pciehp_set_attention_status: SLOTCTRL a8 write cmd c0 pciehp 0000:73:00.0:pcie004: pending interrupts 0x0010 from Slot Status pciehp 0000:73:00.0:pcie004: pending interrupts 0x0010 from Slot Status Actually attention is not changed on both. First one will not generate CC if write not change cmd. Second one will generate CC even if write not change cmd. To avoid those difference interrupts, check if we are trying to write same cmd, if so skip writing. Signed-off-by: Yinghai Lu --- drivers/pci/hotplug/pciehp_hpc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) Index: linux-2.6/drivers/pci/hotplug/pciehp_hpc.c =================================================================== --- linux-2.6.orig/drivers/pci/hotplug/pciehp_hpc.c +++ linux-2.6/drivers/pci/hotplug/pciehp_hpc.c @@ -186,7 +186,7 @@ static void pcie_do_write_cmd(struct con u16 mask, bool wait) { struct pci_dev *pdev = ctrl_dev(ctrl); - u16 slot_ctrl; + u16 slot_ctrl, old_slot_ctrl; mutex_lock(&ctrl->ctrl_lock); @@ -201,8 +201,14 @@ static void pcie_do_write_cmd(struct con goto out; } + old_slot_ctrl = slot_ctrl; slot_ctrl &= ~mask; slot_ctrl |= (cmd & mask); + if (slot_ctrl == old_slot_ctrl) { + ctrl_dbg(ctrl, "%s: mask/cmd %x/%x no change\n", __func__, + mask, cmd & mask); + goto out; + } ctrl->cmd_busy = 1; smp_mb(); pcie_capability_write_word(pdev, PCI_EXP_SLTCTL, slot_ctrl);