diff mbox series

[RESEND,V3,6/6] PCI: Enable 10-Bit tag support for PCIe RP devices

Message ID 1623576555-40338-7-git-send-email-liudongdong3@huawei.com
State New
Headers show
Series PCI: Enable 10-Bit tag support for PCIe devices | expand

Commit Message

Dongdong Liu June 13, 2021, 9:29 a.m. UTC
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(+)

Comments

Christoph Hellwig June 14, 2021, 5:57 a.m. UTC | #1
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).
Dongdong Liu June 15, 2021, 3:08 a.m. UTC | #2
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
> .
>
diff mbox series

Patch

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;
+
+	pci_10bit_tag_comp_support(dev, &support);
+	if (!support)
+		return;
+
+	/*
+	 * 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.
+	 */
+	pci_walk_bus(dev->subordinate, pci_10bit_tag_comp_support, &support);
+	if (!support)
+		return;
+
+	if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_REQ))
+		return;
+
+	pci_dbg(dev, "enabling 10-Bit Tag Requester\n");
+	pcie_capability_set_word(dev, PCI_EXP_DEVCTL2,
+				 PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN);
+}
+
 /*
  * pcie_portdrv_probe - Probe PCI-Express port devices
  * @dev: PCI-Express port device being probed
@@ -111,6 +183,9 @@  static int pcie_portdrv_probe(struct pci_dev *dev,
 	     (type != PCI_EXP_TYPE_RC_EC)))
 		return -ENODEV;
 
+	if (type == PCI_EXP_TYPE_ROOT_PORT)
+		pci_configure_rp_10bit_tag(dev);
+
 	if (type == PCI_EXP_TYPE_RC_EC)
 		pcie_link_rcec(dev);