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SubjectRe: [PATCH] PCI: Fix bit definitions of PCI_EXP_LNKCAP2 register
On Fri, Nov 9, 2012 at 10:37 AM, Alex Deucher <alexdeucher@gmail.com> wrote:
> On Fri, Nov 9, 2012 at 12:15 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>> On Thu, Nov 8, 2012 at 11:56 PM, Jingoo Han <jg1.han@samsung.com> wrote:
>>> According to the PCIe 3.0 spec, PCI_EXP_LNKCAP2_SLS_2_5GB is
>>> 1st bit of PCI_EXP_LNKCAP2 register, not 0th bit. So, the bit
>>> definition of supported link speed vector should be fixed.
>>>
>>> Signed-off-by: Jingoo Han <jg1.han@samsung.com>
>>> ---
>>> include/uapi/linux/pci_regs.h | 6 +++---
>>> 1 files changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
>>> index 20ae747..14a3184 100644
>>> --- a/include/uapi/linux/pci_regs.h
>>> +++ b/include/uapi/linux/pci_regs.h
>>> @@ -544,9 +544,9 @@
>>> #define PCI_EXP_OBFF_WAKE_EN 0x6000 /* OBFF using WAKE# signaling */
>>> #define PCI_CAP_EXP_ENDPOINT_SIZEOF_V2 44 /* v2 endpoints end here */
>>> #define PCI_EXP_LNKCAP2 44 /* Link Capability 2 */
>>> -#define PCI_EXP_LNKCAP2_SLS_2_5GB 0x01 /* Current Link Speed 2.5GT/s */
>>> -#define PCI_EXP_LNKCAP2_SLS_5_0GB 0x02 /* Current Link Speed 5.0GT/s */
>>> -#define PCI_EXP_LNKCAP2_SLS_8_0GB 0x04 /* Current Link Speed 8.0GT/s */
>>> +#define PCI_EXP_LNKCAP2_SLS_2_5GB 0x02 /* Current Link Speed 2.5GT/s */
>>> +#define PCI_EXP_LNKCAP2_SLS_5_0GB 0x04 /* Current Link Speed 5.0GT/s */
>>> +#define PCI_EXP_LNKCAP2_SLS_8_0GB 0x08 /* Current Link Speed 8.0GT/s */
>>> #define PCI_EXP_LNKCAP2_CROSSLINK 0x100 /* Crosslink supported */
>>> #define PCI_EXP_LNKCTL2 48 /* Link Control 2 */
>>> #define PCI_EXP_LNKSTA2 50 /* Link Status 2 */
>>
>> I think this patch is correct, per spec sec 7.8.18. If I apply it, I
>> think the comments should also be changed to "Supported Link Speed"
>> instead of "Current."
>
> Correct.
>
>>
>> The only in-tree user of these symbols is
>> drm_pcie_get_speed_cap_mask(). Dave, can you ack/nack this? I don't
>> want to apply this if it's going to break something there.
>
> The patch is fine and shouldn't break anything.

Thanks for checking this out, Alex.

I applied this to my pci/misc branch as v3.8 material.

Bjorn


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