[igt-dev] [RFC i-g-t 3/5] lib/igt_device_scan: Remember PCI card index after scanning

[Zbigniew Kempczyński]

On Fri, Nov 13, 2020 at 04:27:34PM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> After devices are sorted post scanning, assing a card index to each so it
> can be easily accessed if PCI filter for a card needs to be printed out.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Petri Latvala <petri.latvala at intel.com>
> Cc: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> ---
>  lib/igt_device_scan.c | 43 ++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 36 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/igt_device_scan.c b/lib/igt_device_scan.c
> index c0cd6757fc27..72653403f705 100644
> --- a/lib/igt_device_scan.c
> +++ b/lib/igt_device_scan.c
> @@ -166,6 +166,7 @@ struct igt_device {
>  	char *vendor;
>  	char *device;
>  	char *pci_slot_name;
> +	int pci_index;
>  
>  	struct igt_list_head link;
>  };
> @@ -601,6 +602,33 @@ static void sort_all_devices(void)
>  	free(devs);
>  }
>  
> +static void index_pci_devices(void)
> +{
> +	struct igt_device *dev;
> +
> +	igt_list_for_each_entry(dev, &igt_devs.all, link) {
> +		struct igt_device *dev2;
> +		int index = 0;
> +
> +		if (!is_pci_subsystem(dev))
> +			continue;
> +
> +		igt_list_for_each_entry(dev2, &igt_devs.all, link) {
> +			if (!is_pci_subsystem(dev2))
> +				continue;
> +
> +			if (dev2 == dev)
> +				break;
> +
> +			if (!strcasecmp(dev->vendor, dev2->vendor) &&
> +			    !strcasecmp(dev->device, dev2->device))
> +				index++;
> +		}
> +
> +		dev->pci_index = index;
> +	}
> +}
> +
>  /* Core scanning function.
>   *
>   * All scanned devices are kept inside igt_devs.all pointer array.
> @@ -657,6 +685,7 @@ static void scan_drm_devices(void)
>  	udev_unref(udev);
>  
>  	sort_all_devices();
> +	index_pci_devices();
>  
>  	igt_list_for_each_entry(dev, &igt_devs.all, link) {
>  		struct igt_device *dev_dup = duplicate_device(dev);
> @@ -1105,13 +1134,13 @@ static struct igt_list_head *filter_pci(const struct filter_class *fcls,
>  		if (filter->data.device && strcasecmp(filter->data.device, dev->device))
>  			continue;
>  
> -		/* We get n-th card */
> -		if (!card) {
> -			struct igt_device *dup = duplicate_device(dev);
> -			igt_list_add_tail(&dup->link, &igt_devs.filtered);
> -			break;
> -		}
> -		card--;
> +		/* Skip if 'card' doesn't match */
> +		if (card != dev->pci_index)
> +			continue;
> +
> +		dev = duplicate_device(dev);
> +		igt_list_add_tail(&dev->link, &igt_devs.filtered);
> +		break;

I may wrong (I got no such testing env) but devs_compare() function along with
index_pci_devices() can lead us to such (example) situation:

igt_devs.all contains devices with syspaths and subsystem pci: 
/sys/devices/pci0000:00/0000:00:04.0	-> vendor 8086, device 1234	pci_index == 0
/sys/devices/pci0000:00/0000:00:05.0	-> vendor 8086, device 4321	pci_index == 1
/sys/devices/pci0000:00/0000:00:06.0	-> vendor 8086, device 1234	pci_index == 2

If would try filter: pci=vendor=8086,device=1234,card=1 I would expect
to select (second card [index == 1]) from filtered devices which match
device 1234.

--
Zbigniew

>  	}
>  
>  	DBG("Filter pci filtered size: %d\n", igt_list_length(&igt_devs.filtered));
> -- 
> 2.25.1
>