Re: [PATCH v5 1/3] PCI: Align extra resources for hotplug bridges properly

[Alexander Motin <mav@ixsystems.com>]

Hi Mika,

Unfortunately my system was de-racked meanwhile, so it will take few 
more days for me to test this.  So far I only successfully built it on 
my 5.15.79 kernel.  Meanwhile some comments below:

On 12.01.2023 05:59, Mika Westerberg wrote:
> After division the extra resource space per hotplug bridge may not be
> aligned according to the window alignment so do that before passing it
> down for further distribution.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
>   drivers/pci/setup-bus.c | 25 +++++++++++++++++++------
>   1 file changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index b4096598dbcb..34a74bc581b0 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1891,6 +1891,7 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
>   	 * resource space between hotplug bridges.
>   	 */
>   	for_each_pci_bridge(dev, bus) {
> +		struct resource *res;
>   		struct pci_bus *b;
>   
>   		b = dev->subordinate;
> @@ -1902,16 +1903,28 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
>   		 * hotplug-capable downstream ports taking alignment into
>   		 * account.
>   		 */
> -		io.end = io.start + io_per_hp - 1;
> -		mmio.end = mmio.start + mmio_per_hp - 1;
> -		mmio_pref.end = mmio_pref.start + mmio_pref_per_hp - 1;
> +		res = &dev->resource[PCI_BRIDGE_IO_WINDOW];
> +		align = pci_resource_alignment(dev, res);
> +		io.end = align ? io.start + ALIGN_DOWN(io_per_hp, align) - 1
> +			       : io.start + io_per_hp - 1;

Not bug probably, but if we align x_per_b down for one bridge, we could 
be able to increase it for other(s).

> +
> +		res = &dev->resource[PCI_BRIDGE_MEM_WINDOW];
> +		align = pci_resource_alignment(dev, res);
> +		mmio.end = align ? mmio.start + ALIGN_DOWN(mmio_per_hp, align) - 1
> +				 : mmio.start + io_per_hp - 1;

Here is a typo, it should be mmio_per_hp here   ^^^.

> +
> +		res = &dev->resource[PCI_BRIDGE_PREF_MEM_WINDOW];
> +		align = pci_resource_alignment(dev, res);
> +		mmio_pref.end = align ? mmio_pref.start +
> +					ALIGN_DOWN(mmio_pref_per_hp, align) - 1
> +				      : mmio_pref.start + mmio_pref_per_hp;
>   
>   		pci_bus_distribute_available_resources(b, add_list, io, mmio,
>   						       mmio_pref);
>   
> -		io.start += io_per_hp;
> -		mmio.start += mmio_per_hp;
> -		mmio_pref.start += mmio_pref_per_hp;
> +		io.start += io.end + 1;
> +		mmio.start += mmio.end + 1;
> +		mmio_pref.start += mmio_pref.end + 1;
>   	}
>   }
>   

-- 
Alexander Motin