Re: [PATCH v4 1/9] PCI/PTM: Cache PTM Capability offset

Sathyanarayanan Kuppuswamy
2022-09-09T23:38:09Z

Hi,

On 9/9/22 1:24 PM, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
>
> Cache the PTM Capability offset instead of searching for it every time we
> enable/disable PTM or save/restore PTM state. No functional change
> intended.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Looks good to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

> ---
> drivers/pci/pcie/ptm.c | 41 +++++++++++++++++------------------------
> include/linux/pci.h | 1 +
> 2 files changed, 18 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index 368a254e3124..85382c135885 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -31,13 +31,9 @@ static void pci_ptm_info(struct pci_dev *dev)
>
> void pci_disable_ptm(struct pci_dev *dev)
> {
> - int ptm;
> + u16 ptm = dev->ptm_cap;
> u16 ctrl;
>
> - if (!pci_is_pcie(dev))
> - return;
> -
> - ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> if (!ptm)
> return;
>
> @@ -48,14 +44,10 @@ void pci_disable_ptm(struct pci_dev *dev)
>
> void pci_save_ptm_state(struct pci_dev *dev)
> {
> - int ptm;
> + u16 ptm = dev->ptm_cap;
> struct pci_cap_saved_state *save_state;
> u16 *cap;
>
> - if (!pci_is_pcie(dev))
> - return;
> -
> - ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> if (!ptm)
> return;
>
> @@ -69,16 +61,15 @@ void pci_save_ptm_state(struct pci_dev *dev)
>
> void pci_restore_ptm_state(struct pci_dev *dev)
> {
> + u16 ptm = dev->ptm_cap;
> struct pci_cap_saved_state *save_state;
> - int ptm;
> u16 *cap;
>
> - if (!pci_is_pcie(dev))
> + if (!ptm)
> return;
>
> save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
> - ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> - if (!save_state || !ptm)
> + if (!save_state)
> return;
>
> cap = (u16 *)&save_state->cap.data[0];
> @@ -87,7 +78,7 @@ void pci_restore_ptm_state(struct pci_dev *dev)
>
> void pci_ptm_init(struct pci_dev *dev)
> {
> - int pos;
> + u16 ptm;
> u32 cap, ctrl;
> u8 local_clock;
> struct pci_dev *ups;
> @@ -117,13 +108,14 @@ void pci_ptm_init(struct pci_dev *dev)
> return;
> }
>
> - pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> - if (!pos)
> + ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> + if (!ptm)
> return;
>
> + dev->ptm_cap = ptm;
> pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u16));
>
> - pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
> + pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap);
> local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8;
>
> /*
> @@ -148,7 +140,7 @@ void pci_ptm_init(struct pci_dev *dev)
> }
>
> ctrl |= dev->ptm_granularity << 8;
> - pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
> + pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
> dev->ptm_enabled = 1;
>
> pci_ptm_info(dev);
> @@ -156,18 +148,19 @@ void pci_ptm_init(struct pci_dev *dev)
>
> int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> {
> - int pos;
> + u16 ptm;
> u32 cap, ctrl;
> struct pci_dev *ups;
>
> if (!pci_is_pcie(dev))
> return -EINVAL;
>
> - pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> - if (!pos)
> + ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
> + if (!ptm)
> return -EINVAL;
>
> - pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
> + dev->ptm_cap = ptm;
> + pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap);
> if (!(cap & PCI_PTM_CAP_REQ))
> return -EINVAL;
>
> @@ -192,7 +185,7 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
>
> ctrl = PCI_PTM_CTRL_ENABLE;
> ctrl |= dev->ptm_granularity << 8;
> - pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
> + pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
> dev->ptm_enabled = 1;
>
> pci_ptm_info(dev);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 060af91bafcd..54be939023a3 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -475,6 +475,7 @@ struct pci_dev {
> unsigned int broken_cmd_compl:1; /* No compl for some cmds */
> #endif
> #ifdef CONFIG_PCIE_PTM
> + u16 ptm_cap; /* PTM Capability */
> unsigned int ptm_root:1;
> unsigned int ptm_enabled:1;
> u8 ptm_granularity;

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer