From: Dongdong Liu <liudongdong3@huawei.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: <helgaas@kernel.org>, <kw@linux.com>, <linux-pci@vger.kernel.org>,
<rajur@chelsio.com>, <hverkuil-cisco@xs4all.nl>,
<linux-media@vger.kernel.org>, <netdev@vger.kernel.org>
Subject: Re: [RESEND PATCH V3 6/6] PCI: Enable 10-Bit tag support for PCIe RP devices
Date: Tue, 15 Jun 2021 11:08:05 +0800 [thread overview]
Message-ID: <c2311d23-e4f3-0ec7-4eb0-aa5735b7e9de@huawei.com> (raw)
In-Reply-To: <YMbv0FVV9J53M0L7@infradead.org>
On 2021/6/14 13:57, Christoph Hellwig wrote:
> On Sun, Jun 13, 2021 at 05:29:15PM +0800, Dongdong Liu wrote:
>> PCIe spec 5.0r1.0 section 2.2.6.2 implementation note, In configurations
>> where a Requester with 10-Bit Tag Requester capability needs to target
>> multiple Completers, one needs to ensure that the Requester sends 10-Bit
>> Tag Requests only to Completers that have 10-Bit Tag Completer capability.
>> So we enable 10-Bit Tag Requester for root port only when the devices
>> under the root port support 10-Bit Tag Completer.
>>
>> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
>> ---
>> drivers/pci/pcie/portdrv_pci.c | 75 ++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 75 insertions(+)
>>
>> diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
>> index c7ff1ee..baf413f 100644
>> --- a/drivers/pci/pcie/portdrv_pci.c
>> +++ b/drivers/pci/pcie/portdrv_pci.c
>> @@ -90,6 +90,78 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = {
>> #define PCIE_PORTDRV_PM_OPS NULL
>> #endif /* !PM */
>>
>> +static int pci_10bit_tag_comp_support(struct pci_dev *dev, void *data)
>> +{
>> + u8 *support = data;
>> +
>> + if (*support == 0)
>> + return 0;
>> +
>> + if (!pci_is_pcie(dev)) {
>> + *support = 0;
>> + return 0;
>> + }
>> +
>> + /*
>> + * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note.
>> + * For configurations where a Requester with 10-Bit Tag Requester
>> + * capability targets Completers where some do and some do not have
>> + * 10-Bit Tag Completer capability, how the Requester determines which
>> + * NPRs include 10-Bit Tags is outside the scope of this specification.
>> + * So we do not consider hotplug scenario.
>> + */
>> + if (dev->is_hotplug_bridge) {
>> + *support = 0;
>> + return 0;
>> + }
>> +
>> + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) {
>> + *support = 0;
>> + return 0;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void pci_configure_rp_10bit_tag(struct pci_dev *dev)
>> +{
>> + u8 support = 1;
>> + struct pci_dev *pchild;
>> +
>> + if (dev->subordinate == NULL)
>> + return;
>> +
>> + /* If no devices under the root port, no need to enable 10-Bit Tag. */
>> + pchild = list_first_entry_or_null(&dev->subordinate->devices,
>> + struct pci_dev, bus_list);
>> + if (pchild == NULL)
>> + return;
>
> pchild is never used after this check, so this could be simplified to
> a list_empty(&dev->subordinate->devices).
Good point, will do.
Thanks,
Dongdong
> .
>
prev parent reply other threads:[~2021-06-15 3:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-13 9:29 [RESEND PATCH V3 0/6] PCI: Enable 10-Bit tag support for PCIe devices Dongdong Liu
2021-06-13 9:29 ` [RESEND PATCH V3 1/6] PCI: Use cached Device Capabilities Register Dongdong Liu
2021-06-14 5:42 ` Christoph Hellwig
2021-06-15 3:03 ` Dongdong Liu
2021-06-18 14:51 ` kernel test robot
2021-06-21 7:18 ` Dongdong Liu
2021-06-13 9:29 ` [RESEND PATCH V3 2/6] PCI: Use cached Device Capabilities 2 Register Dongdong Liu
2021-06-14 5:49 ` Christoph Hellwig
2021-06-15 3:04 ` Dongdong Liu
2021-06-13 9:29 ` [RESEND PATCH V3 3/6] PCI: Add 10-Bit Tag register definitions Dongdong Liu
2021-06-14 5:50 ` Christoph Hellwig
2021-06-13 9:29 ` [RESEND PATCH V3 4/6] PCI: Enable 10-Bit tag support for PCIe Endpoint devices Dongdong Liu
2021-06-14 5:54 ` Christoph Hellwig
2021-06-15 3:07 ` Dongdong Liu
2021-06-13 9:29 ` [RESEND PATCH V3 5/6] PCI/IOV: Enable 10-Bit tag support for PCIe VF devices Dongdong Liu
2021-06-14 5:55 ` Christoph Hellwig
2021-06-13 9:29 ` [RESEND PATCH V3 6/6] PCI: Enable 10-Bit tag support for PCIe RP devices Dongdong Liu
2021-06-14 5:57 ` Christoph Hellwig
2021-06-15 3:08 ` Dongdong Liu [this message]
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