On Fri, Nov 02, 2018 at 06:11:07PM +0000, Woods, Brian wrote:
> Add support for new processors which have multiple PCI root complexes
> per data fabric/SMN interface.
Please write out abbreviations. I believe it is only you and I who know
what SMN means. :)
> The interfaces per root complex are redundant and should be skipped.
And I believe it is only you who understands that sentence. :)
Please elaborate why interfaces need to be skipped, *which* interfaces
need to be skipped and which is the correct interface to access DF/SMN
through?
> This makes sure the DF/SMN interfaces get accessed via the correct
> root complex.
>
> Ex:
> DF/SMN 0 -> 60
> 40
> 20
> 00
> DF/SMN 1 -> e0
> c0
> a0
> 80
>
> Signed-off-by: Brian Woods <brian.woods@xxxxxxx>
> ---
> arch/x86/kernel/amd_nb.c | 41 +++++++++++++++++++++++++++++++++++------
> 1 file changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
> index 19d489ee2b1e..c0bf26aeb7c3 100644
> --- a/arch/x86/kernel/amd_nb.c
> +++ b/arch/x86/kernel/amd_nb.c
> @@ -213,7 +213,10 @@ int amd_cache_northbridges(void)
> const struct pci_device_id *root_ids = amd_root_ids;
> struct pci_dev *root, *misc, *link;
> struct amd_northbridge *nb;
> - u16 i = 0;
> + u16 roots_per_misc = 0;
> + u16 misc_count = 0;
> + u16 root_count = 0;
> + u16 i, j;
>
> if (amd_northbridges.num)
> return 0;
> @@ -226,26 +229,52 @@ int amd_cache_northbridges(void)
>
> misc = NULL;
> while ((misc = next_northbridge(misc, misc_ids)) != NULL)
> - i++;
> + misc_count++;
>
> - if (!i)
> + root = NULL;
> + while ((root = next_northbridge(root, root_ids)) != NULL)
> + root_count++;
> +
> + if (!misc_count)
> return -ENODEV;
So you're doing the root_count above but returning in the !misc_count
case. So that root_count iteration was unnecessary work. IOW, you should
keep the misc_count check after its loop.
>
> - nb = kcalloc(i, sizeof(struct amd_northbridge), GFP_KERNEL);
> + if (root_count) {
> + roots_per_misc = root_count / misc_count;
> +
> + /*
> + * There should be _exactly_ N roots for each DF/SMN
> + * interface.
> + */
> + if (!roots_per_misc || (root_count % roots_per_misc)) {
> + pr_info("Unsupported AMD DF/PCI configuration found\n");
> + return -ENODEV;
> + }
> + }
> +
> + nb = kcalloc(misc_count, sizeof(struct amd_northbridge), GFP_KERNEL);
> if (!nb)
> return -ENOMEM;
>
> amd_northbridges.nb = nb;
> - amd_northbridges.num = i;
> + amd_northbridges.num = misc_count;
>
> link = misc = root = NULL;
> - for (i = 0; i != amd_northbridges.num; i++) {
> + for (i = 0; i < amd_northbridges.num; i++) {
> node_to_amd_nb(i)->root = root =
> next_northbridge(root, root_ids);
> node_to_amd_nb(i)->misc = misc =
> next_northbridge(misc, misc_ids);
> node_to_amd_nb(i)->link = link =
> next_northbridge(link, link_ids);
> +
> + /*
> + * If there are more root devices than data fabric/SMN,
> + * interfaces, then the root devices per DF/SMN
> + * interface are redundant and N-1 should be skipped so
> + * they aren't mapped incorrectly.
> + */
This text is trying to explain it a bit better but you still still need
to specify which are the redundant ones. All N-1 or is there a special
root device through which the DF/SMN gets accessed or?
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
