Re: [PATCH edk2-platforms] Silicon/SynQuacerPciHostBridgeLib: enable Gen2 speed

[Leif Lindholm <leif.lindholm@linaro.org>]

On Wed, Nov 29, 2017 at 06:44:59PM +0000, Ard Biesheuvel wrote:
> As it turns out, getting the PCIe controllers to switch to Gen2 speed
> is surprisingly easy. It only involves setting the 'speed change' bit
> in the controller at initialization time, after which the hardware
> will automatically attempt to switch to Gen2 speed after training at
> Gen1 speed has completed.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Hmm?
Well, that sounds like an improvement.
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> ---
>  Silicon/Socionext/SynQuacer/Library/SynQuacerPciHostBridgeLib/SynQuacerPciHostBridgeLibConstructor.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Silicon/Socionext/SynQuacer/Library/SynQuacerPciHostBridgeLib/SynQuacerPciHostBridgeLibConstructor.c b/Silicon/Socionext/SynQuacer/Library/SynQuacerPciHostBridgeLib/SynQuacerPciHostBridgeLibConstructor.c
> index 6b42d3e29806..e63b3a4bb23b 100644
> --- a/Silicon/Socionext/SynQuacer/Library/SynQuacerPciHostBridgeLib/SynQuacerPciHostBridgeLibConstructor.c
> +++ b/Silicon/Socionext/SynQuacer/Library/SynQuacerPciHostBridgeLib/SynQuacerPciHostBridgeLibConstructor.c
> @@ -113,6 +113,9 @@
>  #define PROGRAM_INTERFACE             0x0000FF00
>  #define PROGRAM_INTERFACE_VALUE       0x00
>  
> +#define GEN2_CONTROL_OFF              0x80c
> +#define DIRECT_SPEED_CHANGE           BIT17
> +
>  #define MISC_CONTROL_1_OFF            0x8BC
>  #define DBI_RO_WR_EN                  BIT0
>  
> @@ -295,6 +298,9 @@ PciInitController (
>                                            EFI_PCI_COMMAND_MEMORY_SPACE |
>                                            EFI_PCI_COMMAND_BUS_MASTER);
>  
> +  // Force link speed change to Gen2 at link up
> +  MmioOr32 (DbiBase + GEN2_CONTROL_OFF, DIRECT_SPEED_CHANGE);
> +
>    // Region 0: MMIO32 range
>    ConfigureWindow (DbiBase, 0,
>      RootBridge->Mem.Base,
> -- 
> 2.11.0
>