[PATCH] PCI: enable extended tags support for PCIe endpoints
From: Sinan Kaya <hidden>
Date: 2016-11-10 18:35:47
Also in:
linux-arm-msm, linux-pci, lkml
On 9/24/2016 10:10 PM, Sinan Kaya wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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) +{
I should have checked the capability here before trying to enable it. I'll post a follow up patch on this. Is there any other feedback?
+ 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);-- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.