Re: [Qemu-devel] [PATCH] pcie: Add more ASPM support

[Michael S. Tsirkin]

On Wed, May 15, 2013 at 04:33:08PM -0600, Bjorn Helgaas wrote:
> Indicate ASPM L0s and L1 support in Link Capabilities and make the ASPM
> bits in Link Control writable.  These Link Control bits don't do anything
> in qemu, but having them writable means the BIOS or OS can write them as
> on real hardware.
> 
> Signed-off-by: Bjorn Helgaas <address@hidden>

Out of curiousity - L1 is optional on real hardware, isn't it?
Anyway, went over spec and L1 is just like L0s
but with higher latency, so I think this is a safe change.
A minor comment below - would appreciate if you can address it.

> ---
>  hw/pci/pcie.c              |    4 +++-
>  include/hw/pci/pcie_regs.h |    5 ++++-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index 62bd0b8..7336054 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -73,13 +73,15 @@ int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t 
> type, uint8_t port)
>  
>      pci_set_long(exp_cap + PCI_EXP_LNKCAP,
>                   (port << PCI_EXP_LNKCAP_PN_SHIFT) |
> -                 PCI_EXP_LNKCAP_ASPMS_0S |
> +                 PCI_EXP_LNKCAP_ASPMS_0S | PCI_EXP_LNKCAP_ASPMS_1 |
>                   PCI_EXP_LNK_MLW_1 |
>                   PCI_EXP_LNK_LS_25);
>  
>      pci_set_word(exp_cap + PCI_EXP_LNKSTA,
>                   PCI_EXP_LNK_MLW_1 | PCI_EXP_LNK_LS_25);
>  
> +    pci_set_word(dev->wmask + pos + PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_ASPM);
> +
>      pci_set_long(exp_cap + PCI_EXP_DEVCAP2,
>                   PCI_EXP_DEVCAP2_EFF | PCI_EXP_DEVCAP2_EETLPP);
>  
> diff --git a/include/hw/pci/pcie_regs.h b/include/hw/pci/pcie_regs.h
> index 4d123d9..6b80a8d 100644
> --- a/include/hw/pci/pcie_regs.h
> +++ b/include/hw/pci/pcie_regs.h
> @@ -31,7 +31,7 @@
>  #define PCI_EXP_FLAGS_TYPE_SHIFT        (ffs(PCI_EXP_FLAGS_TYPE) - 1)
>  
>  
> -/* PCI_EXP_LINK{CAP, STA} */
> +/* PCI_EXP_LINK{CAP, STA, CTL} */
>  /* link speed */
>  #define PCI_EXP_LNK_LS_25               1
>  
> @@ -41,9 +41,12 @@
>  /* PCI_EXP_LINKCAP */
>  #define PCI_EXP_LNKCAP_ASPMS_SHIFT      (ffs(PCI_EXP_LNKCAP_ASPMS) - 1)
>  #define PCI_EXP_LNKCAP_ASPMS_0S         (1 << PCI_EXP_LNKCAP_ASPMS_SHIFT)
> +#define PCI_EXP_LNKCAP_ASPMS_1          (2 << PCI_EXP_LNKCAP_ASPMS_SHIFT)
>  
>  #define PCI_EXP_LNKCAP_PN_SHIFT         (ffs(PCI_EXP_LNKCAP_PN) - 1)
>  
> +#define PCI_EXP_LNKCTL_ASPM          0x0003
> +
>  #define PCI_EXP_SLTCAP_PSN_SHIFT        (ffs(PCI_EXP_SLTCAP_PSN) - 1)
>  
>  #define PCI_EXP_SLTCTL_IND_RESERVED     0x0


I'd like to name them the same as you did in linux/pci_regs.h
Let's rename PCI_EXP_LNKCAP_ASPMS_0S/PCI_EXP_LNKCAP_ASPMS_1 as well.


Thanks!