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Subject[RFC PATCH v2 1/4] PCI/ASPM: Remove struct pcie_link_state.parent
Date
From: "Bolarinwa O. Saheed" <refactormyself@gmail.com>

Information cached in struct pcie_link_state.parent is accessible
via struct pci_dev.

This patch:
- removes *parent* from the *struct pcie_link_state*
- creates pci_get_parent() which returns the parent of a pci_dev
- replaces references to pcie_link_state.parent with a call to
pci_get_parent()
- removes BUG_ON(root->parent), instead uses the parent's root

Signed-off-by: Bolarinwa O. Saheed <refactormyself@gmail.com>
---
drivers/pci/pcie/aspm.c | 36 ++++++++++++++++++++++++++----------
1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 013a47f587ce..414c04ffe962 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -50,7 +50,6 @@ struct pcie_link_state {
struct pci_dev *pdev; /* Upstream component of the Link */
struct pci_dev *downstream; /* Downstream component, function 0 */
struct pcie_link_state *root; /* pointer to the root port link */
- struct pcie_link_state *parent; /* pointer to the parent Link state */
struct list_head sibling; /* node in link_list */

/* ASPM state */
@@ -139,6 +138,14 @@ static int policy_to_clkpm_state(struct pcie_link_state *link)
return 0;
}

+static struct pci_dev *pci_get_parent(struct pci_dev *pdev)
+{
+ if (!pdev || !pdev->bus->parent || !pdev->bus->parent->self)
+ return NULL;
+
+ return pdev->bus->parent->self;
+}
+
static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
{
struct pci_dev *child;
@@ -379,6 +386,7 @@ static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
static void pcie_aspm_check_latency(struct pci_dev *endpoint)
{
u32 latency, l1_switch_latency = 0;
+ struct pci_dev *parent;
struct aspm_latency *acceptable;
struct pcie_link_state *link;

@@ -419,7 +427,8 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)
link->aspm_capable &= ~ASPM_STATE_L1;
l1_switch_latency += 1000;

- link = link->parent;
+ parent = pci_get_parent(link->pdev);
+ link = parent ? parent->link_state : NULL;
}
}

@@ -793,9 +802,11 @@ static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)

static void pcie_config_aspm_path(struct pcie_link_state *link)
{
+ struct pci_dev *parent;
while (link) {
pcie_config_aspm_link(link, policy_to_aspm_state(link));
- link = link->parent;
+ parent = pci_get_parent(link->pdev);
+ link = parent ? parent->link_state : NULL;
}
}

@@ -864,16 +875,15 @@ static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev)
!pdev->bus->parent->self) {
link->root = link;
} else {
- struct pcie_link_state *parent;
+ struct pci_dev *parent;

- parent = pdev->bus->parent->self->link_state;
- if (!parent) {
+ parent = pci_get_parent(pdev);
+ if (!parent->link_state) {
kfree(link);
return NULL;
}

- link->parent = parent;
- link->root = link->parent->root;
+ link->root = parent->link_state->root;
}

list_add(&link->sibling, &link_list);
@@ -962,7 +972,11 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
static void pcie_update_aspm_capable(struct pcie_link_state *root)
{
struct pcie_link_state *link;
- BUG_ON(root->parent);
+ struct pci_dev *parent = pci_get_parent(root->pdev);
+
+ if (parent && parent->link_state)
+ root = parent->link_state->root;
+
list_for_each_entry(link, &link_list, sibling) {
if (link->root != root)
continue;
@@ -985,6 +999,7 @@ static void pcie_update_aspm_capable(struct pcie_link_state *root)
/* @pdev: the endpoint device */
void pcie_aspm_exit_link_state(struct pci_dev *pdev)
{
+ struct pci_dev *parent_dev;
struct pci_dev *parent = pdev->bus->self;
struct pcie_link_state *link, *root, *parent_link;

@@ -1002,7 +1017,8 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)

link = parent->link_state;
root = link->root;
- parent_link = link->parent;
+ parent_dev = pci_get_parent(link->pdev);
+ parent_link = parent_dev ? parent_dev->link_state : NULL;

/* All functions are removed, so just disable ASPM for the link */
pcie_config_aspm_link(link, 0);
--
2.20.1
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