[next-queue,v1,1/3] Revert "PCI: Make pci_enable_ptm() private"

Make pci_enable_ptm() accessible from the drivers.

Even if PTM still works on the platform I am using without calling
this this function, it might be possible that it's not always the
case.

Exposing this to the driver enables the driver to use the
'ptm_enabled' field of 'pci_dev' to check if PTM is enabled or not.

This reverts commit ac6c26da29c12fa511c877c273ed5c939dc9e96c.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
---
 drivers/pci/pci.h   | 3 ---
 include/linux/pci.h | 7 +++++++
 2 files changed, 7 insertions(+), 3 deletions(-)

On Fri, Sep 25, 2020 at 04:28:32PM -0700, Vinicius Costa Gomes wrote:
> Make pci_enable_ptm() accessible from the drivers.
> 
> Even if PTM still works on the platform I am using without calling
> this this function, it might be possible that it's not always the
> case.

*Does* PTM work on your system without calling pci_enable_ptm()?  If
so, I think that would mean the BIOS enabled PTM, and that seems
slightly surprising.

> Exposing this to the driver enables the driver to use the
> 'ptm_enabled' field of 'pci_dev' to check if PTM is enabled or not.
> 
> This reverts commit ac6c26da29c12fa511c877c273ed5c939dc9e96c.
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>

AFAICT we just never had any callers at all for pci_enable_ptm().  I
probably shouldn't have merged it in the first place.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/pci.h   | 3 ---
>  include/linux/pci.h | 7 +++++++
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fa12f7cbc1a0..8871109fe390 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -582,11 +582,8 @@ static inline void pcie_ecrc_get_policy(char *str) { }
>  
>  #ifdef CONFIG_PCIE_PTM
>  void pci_ptm_init(struct pci_dev *dev);
> -int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
>  #else
>  static inline void pci_ptm_init(struct pci_dev *dev) { }
> -static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> -{ return -EINVAL; }
>  #endif
>  
>  struct pci_dev_reset_methods {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 835530605c0d..ec4b28153cc4 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1593,6 +1593,13 @@ static inline bool pci_aer_available(void) { return false; }
>  
>  bool pci_ats_disabled(void);
>  
> +#ifdef CONFIG_PCIE_PTM
> +int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
> +#else
> +static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> +{ return -EINVAL; }
> +#endif
> +
>  void pci_cfg_access_lock(struct pci_dev *dev);
>  bool pci_cfg_access_trylock(struct pci_dev *dev);
>  void pci_cfg_access_unlock(struct pci_dev *dev);
> -- 
> 2.28.0
>

Hi,

Bjorn Helgaas <helgaas@kernel.org> writes:

> On Fri, Sep 25, 2020 at 04:28:32PM -0700, Vinicius Costa Gomes wrote:
>> Make pci_enable_ptm() accessible from the drivers.
>> 
>> Even if PTM still works on the platform I am using without calling
>> this this function, it might be possible that it's not always the
>> case.
>
> *Does* PTM work on your system without calling pci_enable_ptm()?  If
> so, I think that would mean the BIOS enabled PTM, and that seems
> slightly surprising.
>

At least it seems to work, yeah, the PTM related registers that I need
for cross timestamping still return valid results when I don't call
pci_enable_ptm().

Btw, I just noticed a typo in the commit message, will fix it for the
v2.

>> Exposing this to the driver enables the driver to use the
>> 'ptm_enabled' field of 'pci_dev' to check if PTM is enabled or not.
>> 
>> This reverts commit ac6c26da29c12fa511c877c273ed5c939dc9e96c.
>> 
>> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
>
> AFAICT we just never had any callers at all for pci_enable_ptm().  I
> probably shouldn't have merged it in the first place.
>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
>

Thanks.