[RFC PATCH v2 0/3] Remove struct pcie_link_state.clkpm_*

[RFC PATCH v2 0/3] Remove struct pcie_link_state.clkpm_*

[Saheed O. Bolarinwa]

These series removes the Clock PM members of the
struct pcie_link_state. Another member is introduced to mark
devices that the kernel has disbled.

VERSION CHANGES:
 - v2:
	- clkpm_default and clkpm_disable are now left out.
	- improve pcie_is_clkpm_capable() based on review.
	- replace pcie_get_clkpm_state() with pcie_clkpm_enabled().

MERGE NOTICE:
These series are based on
»       'commit e4e737bb5c17 ("Linux 5.15-rc2")'

Saheed O. Bolarinwa (3):
  PCI/ASPM: Merge pcie_set_clkpm_nocheck() into pcie_set_clkpm()
  PCI/ASPM: Remove struct pcie_link_state.clkpm_capable
  PCI/ASPM: Remove struct pcie_link_state.clkpm_enabled

 drivers/pci/pcie/aspm.c | 82 +++++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 40 deletions(-)

-- 
2.20.1

[RFC PATCH v2 1/3] PCI/ASPM: Merge pcie_set_clkpm_nocheck() into pcie_set_clkpm()

[Saheed O. Bolarinwa]

pcie_set_clkpm_nocheck() is only called from pcie_set_clkpm().

Merge the two functions

Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
---
 drivers/pci/pcie/aspm.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 013a47f587ce..e5202cc16ef0 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -139,21 +139,12 @@ static int policy_to_clkpm_state(struct pcie_link_state *link)
 	return 0;
 }
 
-static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
+static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 {
+	u32 val;
 	struct pci_dev *child;
 	struct pci_bus *linkbus = link->pdev->subordinate;
-	u32 val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
-
-	list_for_each_entry(child, &linkbus->devices, bus_list)
-		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
-						   PCI_EXP_LNKCTL_CLKREQ_EN,
-						   val);
-	link->clkpm_enabled = !!enable;
-}
 
-static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
-{
 	/*
 	 * Don't enable Clock PM if the link is not Clock PM capable
 	 * or Clock PM is disabled
@@ -163,7 +154,14 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 	/* Need nothing if the specified equals to current state */
 	if (link->clkpm_enabled == enable)
 		return;
-	pcie_set_clkpm_nocheck(link, enable);
+
+	val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
+	list_for_each_entry(child, &linkbus->devices, bus_list)
+		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_CLKREQ_EN,
+						   val);
+
+	link->clkpm_enabled = !!enable;
 }
 
 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
-- 
2.20.1

[RFC PATCH v2 2/3] PCI/ASPM: Remove struct pcie_link_state.clkpm_capable

[Saheed O. Bolarinwa]

The clkpm_capable member of the struct pcie_link_state indicates
if the device is Clock PM capable. This can be calculated when
it is needed, because it comes from Link Capabilities, a read-only
register.

  - remove clkpm_capable from struct pcie_link_state
  - move the calculation of clkpm_capable into
    pcie_is_clkpm_capable()
  - replace references to clkpm_capable with a call to
    pcie_is_clkpm_capable()

Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
---
 drivers/pci/pcie/aspm.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index e5202cc16ef0..c1f8f10b7a4c 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -61,7 +61,6 @@ struct pcie_link_state {
 	u32 aspm_disable:7;		/* Disabled ASPM state */
 
 	/* Clock PM state */
-	u32 clkpm_capable:1;		/* Clock PM capable? */
 	u32 clkpm_enabled:1;		/* Current Clock PM state */
 	u32 clkpm_default:1;		/* Default Clock PM state by BIOS */
 	u32 clkpm_disable:1;		/* Clock PM disabled */
@@ -105,6 +104,20 @@ static const char *policy_str[] = {
 
 #define LINK_RETRAIN_TIMEOUT HZ
 
+static int pcie_clkpm_capable(struct pci_dev *pdev)
+{
+	u32 cap;
+	struct pci_dev *child;
+	struct pci_bus *linkbus = pdev->subordinate;
+
+	list_for_each_entry(child, &linkbus->devices, bus_list) {
+		pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &cap);
+		if (!(cap & PCI_EXP_LNKCAP_CLKPM))
+			return 0;
+	}
+	return 1;
+}
+
 static int policy_to_aspm_state(struct pcie_link_state *link)
 {
 	switch (aspm_policy) {
@@ -149,7 +162,7 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 	 * Don't enable Clock PM if the link is not Clock PM capable
 	 * or Clock PM is disabled
 	 */
-	if (!link->clkpm_capable || link->clkpm_disable)
+	if (!pcie_clkpm_capable(link->pdev) || link->clkpm_disable)
 		enable = 0;
 	/* Need nothing if the specified equals to current state */
 	if (link->clkpm_enabled == enable)
@@ -166,7 +179,7 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 
 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 {
-	int capable = 1, enabled = 1;
+	int enabled = 1;
 	u32 reg32;
 	u16 reg16;
 	struct pci_dev *child;
@@ -176,7 +189,6 @@ static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 	list_for_each_entry(child, &linkbus->devices, bus_list) {
 		pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &reg32);
 		if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
-			capable = 0;
 			enabled = 0;
 			break;
 		}
@@ -186,7 +198,6 @@ static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 	}
 	link->clkpm_enabled = enabled;
 	link->clkpm_default = enabled;
-	link->clkpm_capable = capable;
 	link->clkpm_disable = blacklist ? 1 : 0;
 }
 
@@ -1327,7 +1338,7 @@ static umode_t aspm_ctrl_attrs_are_visible(struct kobject *kobj,
 		return 0;
 
 	if (n == 0)
-		return link->clkpm_capable ? a->mode : 0;
+		return pcie_clkpm_capable(link->pdev) ? a->mode : 0;
 
 	return link->aspm_capable & aspm_state_map[n - 1] ? a->mode : 0;
 }
-- 
2.20.1

[RFC PATCH v2 3/3] PCI/ASPM: Remove struct pcie_link_state.clkpm_enabled

[Saheed O. Bolarinwa]

The clkpm_enabled member of the struct pcie_link_state stores the
current Clock PM state for the device. However, when the state changes
it is persisted and thus can be retieved directly.

   - move calculations into pcie_clkpm_enabled()
   - removes clkpm_enabled from the struct pcie_link_state
   - removes all instance where clkpm_enable is set
   - replaces references to clkpm_enabled with a call to
     pcie_get_clkpm_state()

Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
---
 drivers/pci/pcie/aspm.c | 43 +++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 25 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index c1f8f10b7a4c..9425d1e38c51 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -61,7 +61,6 @@ struct pcie_link_state {
 	u32 aspm_disable:7;		/* Disabled ASPM state */
 
 	/* Clock PM state */
-	u32 clkpm_enabled:1;		/* Current Clock PM state */
 	u32 clkpm_default:1;		/* Default Clock PM state by BIOS */
 	u32 clkpm_disable:1;		/* Clock PM disabled */
 
@@ -104,6 +103,21 @@ static const char *policy_str[] = {
 
 #define LINK_RETRAIN_TIMEOUT HZ
 
+static int pcie_clkpm_enabled(struct pci_dev *pdev)
+{
+	struct pci_dev *child;
+	struct pci_bus *linkbus = pdev->subordinate;
+	u16 ctl;
+
+	/* CLKREQ_EN is only applicable for Upstream Ports */
+	list_for_each_entry(child, &linkbus->devices, bus_list) {
+		pcie_capability_read_word(child, PCI_EXP_LNKCTL, &ctl);
+		if (!(ctl & PCI_EXP_LNKCTL_CLKREQ_EN))
+			return 0;
+	}
+	return 1;
+}
+
 static int pcie_clkpm_capable(struct pci_dev *pdev)
 {
 	u32 cap;
@@ -165,7 +179,7 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 	if (!pcie_clkpm_capable(link->pdev) || link->clkpm_disable)
 		enable = 0;
 	/* Need nothing if the specified equals to current state */
-	if (link->clkpm_enabled == enable)
+	if (pcie_clkpm_enabled(link->pdev) == enable)
 		return;
 
 	val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
@@ -173,31 +187,11 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
 		pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
 						   PCI_EXP_LNKCTL_CLKREQ_EN,
 						   val);
-
-	link->clkpm_enabled = !!enable;
 }
 
 static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 {
-	int enabled = 1;
-	u32 reg32;
-	u16 reg16;
-	struct pci_dev *child;
-	struct pci_bus *linkbus = link->pdev->subordinate;
-
-	/* All functions should have the same cap and state, take the worst */
-	list_for_each_entry(child, &linkbus->devices, bus_list) {
-		pcie_capability_read_dword(child, PCI_EXP_LNKCAP, &reg32);
-		if (!(reg32 & PCI_EXP_LNKCAP_CLKPM)) {
-			enabled = 0;
-			break;
-		}
-		pcie_capability_read_word(child, PCI_EXP_LNKCTL, &reg16);
-		if (!(reg16 & PCI_EXP_LNKCTL_CLKREQ_EN))
-			enabled = 0;
-	}
-	link->clkpm_enabled = enabled;
-	link->clkpm_default = enabled;
+	link->clkpm_default = pcie_clkpm_enabled(link->pdev);
 	link->clkpm_disable = blacklist ? 1 : 0;
 }
 
@@ -1272,9 +1266,8 @@ static ssize_t clkpm_show(struct device *dev,
 			  struct device_attribute *attr, char *buf)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
-	struct pcie_link_state *link = pcie_aspm_get_link(pdev);
 
-	return sysfs_emit(buf, "%d\n", link->clkpm_enabled);
+	return sysfs_emit(buf, "%d\n", pcie_clkpm_enabled(pdev));
 }
 
 static ssize_t clkpm_store(struct device *dev,
-- 
2.20.1