lkml.org 
[lkml]   [2018]   [Apr]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH v5 05/14] PCI: Add pcie_print_link_status() to log link speed and whether it's limited
Date
> -----Original Message-----
> From: Bjorn Helgaas [mailto:helgaas@kernel.org]
> Sent: Friday, March 30, 2018 2:05 PM
> To: Tal Gilboa <talgi@mellanox.com>
> Cc: Tariq Toukan <tariqt@mellanox.com>; Keller, Jacob E
> <jacob.e.keller@intel.com>; Ariel Elior <ariel.elior@cavium.com>; Ganesh
> Goudar <ganeshgr@chelsio.com>; Kirsher, Jeffrey T
> <jeffrey.t.kirsher@intel.com>; everest-linux-l2@cavium.com; intel-wired-
> lan@lists.osuosl.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-pci@vger.kernel.org
> Subject: [PATCH v5 05/14] PCI: Add pcie_print_link_status() to log link speed and
> whether it's limited
>
> From: Tal Gilboa <talgi@mellanox.com>
>
> Add pcie_print_link_status(). This logs the current settings of the link
> (speed, width, and total available bandwidth).
>
> If the device is capable of more bandwidth but is limited by a slower
> upstream link, we include information about the link that limits the
> device's performance.
>
> The user may be able to move the device to a different slot for better
> performance.
>
> This provides a unified method for all PCI devices to report status and
> issues, instead of each device reporting in a different way, using
> different code.
>
> Signed-off-by: Tal Gilboa <talgi@mellanox.com>
> [bhelgaas: changelog, reword log messages, print device capabilities when
> not limited]
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pci/pci.c | 29 +++++++++++++++++++++++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 30 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e00d56b12747..cec7aed09f6b 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5283,6 +5283,35 @@ u32 pcie_bandwidth_capable(struct pci_dev *dev,
> enum pci_bus_speed *speed,
> return *width * PCIE_SPEED2MBS_ENC(*speed);
> }
>
> +/**
> + * pcie_print_link_status - Report the PCI device's link speed and width
> + * @dev: PCI device to query
> + *
> + * Report the available bandwidth at the device. If this is less than the
> + * device is capable of, report the device's maximum possible bandwidth and
> + * the upstream link that limits its performance to less than that.
> + */
> +void pcie_print_link_status(struct pci_dev *dev)
> +{
> + enum pcie_link_width width, width_cap;
> + enum pci_bus_speed speed, speed_cap;
> + struct pci_dev *limiting_dev = NULL;
> + u32 bw_avail, bw_cap;
> +
> + bw_cap = pcie_bandwidth_capable(dev, &speed_cap, &width_cap);
> + bw_avail = pcie_bandwidth_available(dev, &limiting_dev, &speed,
> &width);
> +
> + if (bw_avail >= bw_cap)
> + pci_info(dev, "%d Mb/s available bandwidth (%s x%d link)\n",
> + bw_cap, PCIE_SPEED2STR(speed_cap), width_cap);
> + else
> + pci_info(dev, "%d Mb/s available bandwidth, limited by %s x%d
> link at %s (capable of %d Mb/s with %s x%d link)\n",
> + bw_avail, PCIE_SPEED2STR(speed), width,
> + limiting_dev ? pci_name(limiting_dev) : "<unknown>",
> + bw_cap, PCIE_SPEED2STR(speed_cap), width_cap);
> +}

Personally, I would make thic last one a pci_warn() to indicate it at a higher log level, but I'm ok with the wording, and if consensus is that this should be at info, I'm ok with that.

Thanks,
Jake

> +EXPORT_SYMBOL(pcie_print_link_status);
> +
> /**
> * pci_select_bars - Make BAR mask from the type of resource
> * @dev: the PCI device for which BAR mask is made
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index f2bf2b7a66c7..38f7957121ef 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1086,6 +1086,7 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum
> pci_bus_speed *speed,
> u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev
> **limiting_dev,
> enum pci_bus_speed *speed,
> enum pcie_link_width *width);
> +void pcie_print_link_status(struct pci_dev *dev);
> void pcie_flr(struct pci_dev *dev);
> int __pci_reset_function_locked(struct pci_dev *dev);
> int pci_reset_function(struct pci_dev *dev);

\
 
 \ /
  Last update: 2018-04-02 18:26    [W:0.212 / U:6.956 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site