[PATCH V7 1/9] PCI: Use cached Device Capabilities Register

Dongdong Liu
2021-08-04T13:49:27Z

It will make sense to store the pcie_devcap value in the pci_dev
structure instead of reading Device Capabilities Register multiple
times. The fisrt place to use pcie_devcap is in set_pcie_port_type(),
get the pcie_devcap value here, then use cached pcie_devcap in the
needed place.

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
drivers/media/pci/cobalt/cobalt-driver.c | 5 +++--
drivers/pci/pci.c | 5 +----
drivers/pci/pcie/aspm.c | 11 ++++-------
drivers/pci/probe.c | 11 +++--------
drivers/pci/quirks.c | 3 +--
include/linux/pci.h | 1 +
6 files changed, 13 insertions(+), 23 deletions(-)

diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
index 16af58f..23c6436 100644
--- a/drivers/media/pci/cobalt/cobalt-driver.c
+++ b/drivers/media/pci/cobalt/cobalt-driver.c
@@ -193,11 +193,12 @@ void cobalt_pcie_status_show(struct cobalt *cobalt)
return;

/* Device */
- pcie_capability_read_dword(pci_dev, PCI_EXP_DEVCAP, &capa);
pcie_capability_read_word(pci_dev, PCI_EXP_DEVCTL, &ctrl);
pcie_capability_read_word(pci_dev, PCI_EXP_DEVSTA, &stat);
cobalt_info("PCIe device capability 0x%08x: Max payload %d\n",
- capa, get_payload_size(capa & PCI_EXP_DEVCAP_PAYLOAD));
+ pci_dev->pcie_devcap,
+ get_payload_size(pci_dev->pcie_devcap &
+ PCI_EXP_DEVCAP_PAYLOAD));
cobalt_info("PCIe device control 0x%04x: Max payload %d. Max read request %d\n",
ctrl,
get_payload_size((ctrl & PCI_EXP_DEVCTL_PAYLOAD) >> 5),
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index aacf575..dc3bfb2 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4630,13 +4630,10 @@ EXPORT_SYMBOL(pci_wait_for_pending_transaction);
*/
bool pcie_has_flr(struct pci_dev *dev)
{
- u32 cap;
-
if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
return false;

- pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
- return cap & PCI_EXP_DEVCAP_FLR;
+ return dev->pcie_devcap & PCI_EXP_DEVCAP_FLR;
}
EXPORT_SYMBOL_GPL(pcie_has_flr);

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 013a47f..db944f6 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -660,7 +660,7 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)

/* Get and check endpoint acceptable latencies */
list_for_each_entry(child, &linkbus->devices, bus_list) {
- u32 reg32, encoding;
+ u32 encoding;
struct aspm_latency *acceptable =
&link->acceptable[PCI_FUNC(child->devfn)];

@@ -668,12 +668,11 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END)
continue;

- pcie_capability_read_dword(child, PCI_EXP_DEVCAP, &reg32);
/* Calculate endpoint L0s acceptable latency */
- encoding = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6;
+ encoding = (child->pcie_devcap & PCI_EXP_DEVCAP_L0S) >> 6;
acceptable->l0s = calc_l0s_acceptable(encoding);
/* Calculate endpoint L1 acceptable latency */
- encoding = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
+ encoding = (child->pcie_devcap & PCI_EXP_DEVCAP_L1) >> 9;
acceptable->l1 = calc_l1_acceptable(encoding);

pcie_aspm_check_latency(child);
@@ -808,7 +807,6 @@ static void free_link_state(struct pcie_link_state *link)
static int pcie_aspm_sanity_check(struct pci_dev *pdev)
{
struct pci_dev *child;
- u32 reg32;

/*
* Some functions in a slot might not all be PCIe functions,
@@ -831,8 +829,7 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
* Disable ASPM for pre-1.1 PCIe device, we follow MS to use
* RBER bit to determine if a function is 1.1 version device
*/
- pcie_capability_read_dword(child, PCI_EXP_DEVCAP, &reg32);
- if (!(reg32 & PCI_EXP_DEVCAP_RBER) && !aspm_force) {
+ if (!(child->pcie_devcap & PCI_EXP_DEVCAP_RBER) && !aspm_force) {
pci_info(child, "disabling ASPM on pre-1.1 PCIe device. You can enable it with 'pcie_aspm=force'\n");
return -EINVAL;
}
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 79177ac..cc700f6 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1498,8 +1498,8 @@ void set_pcie_port_type(struct pci_dev *pdev)
pdev->pcie_cap = pos;
pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
pdev->pcie_flags_reg = reg16;
- pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, &reg16);
- pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;
+ pci_read_config_dword(pdev, pos + PCI_EXP_DEVCAP, &pdev->pcie_devcap);
+ pdev->pcie_mpss = pdev->pcie_devcap & PCI_EXP_DEVCAP_PAYLOAD;

parent = pci_upstream_bridge(pdev);
if (!parent)
@@ -2031,18 +2031,13 @@ static void pci_configure_mps(struct pci_dev *dev)
int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
{
struct pci_host_bridge *host;
- u32 cap;
u16 ctl;
int ret;

if (!pci_is_pcie(dev))
return 0;

- ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
- if (ret)
- return 0;
-
- if (!(cap & PCI_EXP_DEVCAP_EXT_TAG))
+ if (!(dev->pcie_devcap & PCI_EXP_DEVCAP_EXT_TAG))
return 0;

ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 6d74386..2b405c5 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5173,8 +5173,7 @@ static void quirk_intel_qat_vf_cap(struct pci_dev *pdev)
pdev->pcie_cap = pos;
pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
pdev->pcie_flags_reg = reg16;
- pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, &reg16);
- pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;
+ pdev->pcie_mpss = pdev->pcie_devcap & PCI_EXP_DEVCAP_PAYLOAD;

pdev->cfg_size = PCI_CFG_SPACE_EXP_SIZE;
if (pci_read_config_dword(pdev, PCI_CFG_SPACE_SIZE, &status) !=
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 540b377..aee7c85 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -340,6 +340,7 @@ struct pci_dev {
u8 rom_base_reg; /* Config register controlling ROM */
u8 pin; /* Interrupt pin this device uses */
u16 pcie_flags_reg; /* Cached PCIe Capabilities Register */
+ u32 pcie_devcap; /* Cached Device Capabilities Register */
unsigned long *dma_alias_mask;/* Mask of enabled devfn aliases */

struct pci_driver *driver; /* Driver bound to this device */
--
2.7.4