[PATCH i-g-t v3 1/6] lib/igt_sysfs: Add support for device unbinding

[Lucas De Marchi]

On Thu, Mar 06, 2025 at 03:40:36PM +0530, Satyanarayana K V P wrote:
>It does not harm anything when we try to unbind a device which
>is already unbinded. We do not want to throw assertion when
>the device is already unbinded.
>
>Signed-off-by: Satyanarayana K V P <satyanarayana.k.v.p at intel.com>
>Cc: Michał Wajdeczko <michal.wajdeczko at intel.com>
>Cc: Francois Dugast <francois.dugast at intel.com>
>Reviewed-by: Francois Dugast <francois.dugast at intel.com>
>---
> lib/igt_sysfs.c | 4 ++++
> lib/igt_sysfs.h | 1 +
> 2 files changed, 5 insertions(+)
>
>diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
>index 2e4c2ee63..3fffaf96b 100644
>--- a/lib/igt_sysfs.c
>+++ b/lib/igt_sysfs.c
>@@ -1509,6 +1509,10 @@ int xe_sysfs_driver_do(int xe_device, char pci_slot[], enum xe_sysfs_driver_acti
> 		igt_assert(igt_sysfs_set(sysfs, "unbind", pci_slot));
> 		close(sysfs);
> 		break;
>+	case XE_SYSFS_DRIVER_TRY_UNBIND:

oh no, this function uses the wrong design, let's not make it worse.
xe_sysfs_driver_do() should really be dropped and we should use the
proper functions.

It's also in the wrong lib layer. igt_sysfs is for supporting sysfs
things like opening, writing, mapping from a device to the right
directory, setting an value, etc. We shouldn't do to do arbitrary thing
**using** sysfs.

Finally, when we want to unbind we shouldn't really pass an fd. The
caller has no idea if the library function will close it or not. That
triggers several different paths in the kernel as userspace holds or not
an fd open.

Please do not more to this function. We already have igt_kmod_unbind(),
we could have igt_kmod_unbind_device(). As we could have dedicated
functions in the right layer for all the other actions here.

Lucas De Marchi