Re: [PATCH] PCI: add pcie max_payload_size debug info

[Jiang Liu <jiang.liu@huawei.com>]

Why not update MPS setting when hot-adding a PCI device?
On 2012-10-9 11:02, Yijing Wang wrote:
> PCIe device mps maybe not equal to its bridge mps after doing pci hotplug.
> This may result unexpected problem like
> http://marc.info/?l=linux-scsi&m=134788365823217&w=2. So add mps log for current
> mps setting to help diagnosis an issue like this.
> 
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
>  drivers/pci/probe.c |   38 ++++++++++++++++++++++++++++++++++++++
>  1 files changed, 38 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ec909af..ff1f98d 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1533,6 +1533,42 @@ static void pcie_write_mrrs(struct pci_dev *dev)
>  			"with pci=pcie_bus_safe.\n");
>  }
>  
> +static void pcie_dump_bus_mps(struct pci_bus *bus);
> +
> +static void pcie_dump_dev_mps(struct pci_dev *dev)
> +{
> +	int mps, mpss;
> +
> +	if (!pci_is_pcie(dev))
> +		return;
> +
> +	if (dev->subordinate)
> +		pcie_dump_bus_mps(dev->subordinate);
> +	else {
> +		mps = pcie_get_mps(dev);
> +		mpss = 128 << dev->pcie_mpss;
> +		dev_printk(KERN_DEBUG, &dev->dev, "PCI-E Max_Payload_Size Supported %d, "
> +			"Max_Payload_Size %d\n", mpss, mps);
> +	}
> +}
> +
> +static void pcie_dump_bus_mps(struct pci_bus *bus)
> +{
> +	int mps, mpss;
> +	struct pci_dev *dev;
> +
> +	if (!bus->self || !pci_is_pcie(bus->self))
> +		return;
> +
> +	mps = pcie_get_mps(bus->self);
> +	mpss = 128 << bus->self->pcie_mpss;
> +	dev_printk(KERN_DEBUG, &bus->self->dev, "PCI-E Max_Payload_Size Supported %d, "
> +		"Max_Payload_Size %d\n", mpss, mps);
> +
> +	list_for_each_entry(dev, &bus->devices, bus_list)
> +		pcie_dump_dev_mps(dev);
> +}
> +
>  static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
>  {
>  	int mps, orig_mps;
> @@ -1564,6 +1600,8 @@ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
>  	if (!pci_is_pcie(bus->self))
>  		return;
>  
> +	pcie_dump_bus_mps(bus);
> +
>  	if (pcie_bus_config == PCIE_BUS_TUNE_OFF)
>  		return;
>