On Fri, Oct 25, 2019 at 10:01 PM Stuart Hayes <stuart.w.hayes@xxxxxxxxx> wrote:
>
> Some systems have in-band presence detection disabled for hot-plug PCI
> slots, but do not report this in the slot capabilities 2 (SLTCAP2) register.
> On these systems, presence detect can become active well after the link is
> reported to be active, which can cause the slots to be disabled after a
> device is connected.
>
> Add a dmi table to flag these systems as having in-band presence disabled.
>
FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Signed-off-by: Stuart Hayes <stuart.w.hayes@xxxxxxxxx>
> ---
> v4
> add comment to dmi table
>
> drivers/pci/hotplug/pciehp_hpc.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 02d95ab27a12..9541735bd0aa 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -14,6 +14,7 @@
>
> #define dev_fmt(fmt) "pciehp: " fmt
>
> +#include <linux/dmi.h>
> #include <linux/kernel.h>
> #include <linux/types.h>
> #include <linux/jiffies.h>
> @@ -26,6 +27,24 @@
> #include "../pci.h"
> #include "pciehp.h"
>
> +static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
> + /*
> + * Match all Dell systems, as some Dell systems have inband
> + * presence disabled on NVMe slots (but don't support the bit to
> + * report it). Setting inband presence disabled should have no
> + * negative effect, except on broken hotplug slots that never
> + * assert presence detect--and those will still work, they will
> + * just have a bit of extra delay before being probed.
> + */
> + {
> + .ident = "Dell System",
> + .matches = {
> + DMI_MATCH(DMI_OEM_STRING, "Dell System"),
> + },
> + },
> + {}
> +};
> +
> static inline struct pci_dev *ctrl_dev(struct controller *ctrl)
> {
> return ctrl->pcie->port;
> @@ -895,6 +914,9 @@ struct controller *pcie_init(struct pcie_device *dev)
> ctrl->inband_presence_disabled = 1;
> }
>
> + if (dmi_first_match(inband_presence_disabled_dmi_table))
> + ctrl->inband_presence_disabled = 1;
> +
> /*
> * If empty slot's power status is on, turn power off. The IRQ isn't
> * requested yet, so avoid triggering a notification with this command.
> --
> 2.18.1
>
--
With Best Regards,
Andy Shevchenko
