Re: [PATCH v7 2/3] PCI: Move pci_bus_speed2lnkctl2() to public header

[Bjorn Helgaas]

On Tue, Apr 07, 2026 at 09:04:49PM +0800, Hans Zhang wrote:
> Move the static array-based pci_bus_speed2lnkctl2() function from
> bwctrl.c to pci.h as a public inline function.
> 
> This provides efficient O(1) speed-to-LNKCTL2 value conversion using
> static array lookup, maintaining optimal performance while enabling
> code reuse by other PCIe drivers.
> 
> Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> Reviewed-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

> ---
>  drivers/pci/pci.h         | 18 ++++++++++++++++++
>  drivers/pci/pcie/bwctrl.c | 17 -----------------
>  2 files changed, 18 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index f0a082bfd6f1..e0c2630e93f2 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -2,6 +2,7 @@
>  #ifndef DRIVERS_PCI_H
>  #define DRIVERS_PCI_H
>  
> +#include <asm/bug.h>
>  #include <linux/align.h>
>  #include <linux/bitfield.h>
>  #include <linux/pci.h>
> @@ -611,6 +612,23 @@ static inline bool pcie_valid_speed(enum pci_bus_speed speed)
>  	return (speed >= PCIE_SPEED_2_5GT) && (speed <= PCIE_SPEED_64_0GT);
>  }
>  
> +static inline u16 pci_bus_speed2lnkctl2(enum pci_bus_speed speed)
> +{
> +	static const u8 speed_conv[] = {
> +		[PCIE_SPEED_2_5GT] = PCI_EXP_LNKCTL2_TLS_2_5GT,
> +		[PCIE_SPEED_5_0GT] = PCI_EXP_LNKCTL2_TLS_5_0GT,
> +		[PCIE_SPEED_8_0GT] = PCI_EXP_LNKCTL2_TLS_8_0GT,
> +		[PCIE_SPEED_16_0GT] = PCI_EXP_LNKCTL2_TLS_16_0GT,
> +		[PCIE_SPEED_32_0GT] = PCI_EXP_LNKCTL2_TLS_32_0GT,
> +		[PCIE_SPEED_64_0GT] = PCI_EXP_LNKCTL2_TLS_64_0GT,
> +	};
> +
> +	if (WARN_ON_ONCE(!pcie_valid_speed(speed)))
> +		return 0;
> +
> +	return speed_conv[speed];
> +}
> +
>  static inline int pcie_dev_speed_mbps(enum pci_bus_speed speed)
>  {
>  	switch (speed) {
> diff --git a/drivers/pci/pcie/bwctrl.c b/drivers/pci/pcie/bwctrl.c
> index ea82e326f164..d48021bfd844 100644
> --- a/drivers/pci/pcie/bwctrl.c
> +++ b/drivers/pci/pcie/bwctrl.c
> @@ -48,23 +48,6 @@ struct pcie_bwctrl_data {
>  /* Prevent port removal during Link Speed changes. */
>  static DECLARE_RWSEM(pcie_bwctrl_setspeed_rwsem);
>  
> -static u16 pci_bus_speed2lnkctl2(enum pci_bus_speed speed)
> -{
> -	static const u8 speed_conv[] = {
> -		[PCIE_SPEED_2_5GT] = PCI_EXP_LNKCTL2_TLS_2_5GT,
> -		[PCIE_SPEED_5_0GT] = PCI_EXP_LNKCTL2_TLS_5_0GT,
> -		[PCIE_SPEED_8_0GT] = PCI_EXP_LNKCTL2_TLS_8_0GT,
> -		[PCIE_SPEED_16_0GT] = PCI_EXP_LNKCTL2_TLS_16_0GT,
> -		[PCIE_SPEED_32_0GT] = PCI_EXP_LNKCTL2_TLS_32_0GT,
> -		[PCIE_SPEED_64_0GT] = PCI_EXP_LNKCTL2_TLS_64_0GT,
> -	};
> -
> -	if (WARN_ON_ONCE(!pcie_valid_speed(speed)))
> -		return 0;
> -
> -	return speed_conv[speed];
> -}
> -
>  static inline u16 pcie_supported_speeds2target_speed(u8 supported_speeds)
>  {
>  	return __fls(supported_speeds);
> -- 
> 2.34.1
>