From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org ([198.145.29.96]:59674 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965459AbcIYCKm (ORCPT ); Sat, 24 Sep 2016 22:10:42 -0400 From: Sinan Kaya To: linux-pci@vger.kernel.org, timur@codeaurora.org, cov@codeaurora.org, vikrams@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , linux-kernel@vger.kernel.org Subject: [PATCH] PCI: enable extended tags support for PCIe endpoints Date: Sat, 24 Sep 2016 22:10:34 -0400 Message-Id: <1474769434-5756-1-git-send-email-okaya@codeaurora.org> Sender: linux-pci-owner@vger.kernel.org List-ID: Each PCIe device can issue up to 32 transactions at a time by default. Each transaction is tracked by a tag number on the bus. 32 outstanding transactions is not enough for some performance critical applications especially when a lot of small sized frames are transmitted. Extended tags support increases this number to 256. Devices not supporting extended tags tie-off this field to 0. According to ECN, it is safe to enable this feature for all PCIe endpoints. Signed-off-by: Sinan Kaya --- drivers/pci/probe.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 93f280d..2424f38 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1505,12 +1505,19 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp) */ } +static int pci_configure_extended_tags(struct pci_dev *dev) +{ + return pcie_capability_set_word(dev, PCI_EXP_DEVCTL, + PCI_EXP_DEVCTL_EXT_TAG); +} + static void pci_configure_device(struct pci_dev *dev) { struct hotplug_params hpp; int ret; pci_configure_mps(dev); + pci_configure_extended_tags(dev); memset(&hpp, 0, sizeof(hpp)); ret = pci_get_hp_params(dev, &hpp); -- 1.9.1