[PATCH 8/9] drm/xe/xe_late_bind_fw: Introduce debug fs node to disable late binding

[Rodrigo Vivi]

On Thu, Jul 31, 2025 at 08:03:36PM +0000, Summers, Stuart wrote:
> On Thu, 2025-07-10 at 11:08 -0400, Rodrigo Vivi wrote:
> > From: Badal Nilawar <badal.nilawar at intel.com>
> > 
> > Introduce a debug filesystem node to disable late binding fw reload
> > during the system or runtime resume. This is intended for situations
> > where the late binding fw needs to be loaded from user mode,
> > perticularly for validation purpose.
> > Note that xe kmd doesn't participate in late binding flow from user
> > space. Binary loaded from the userspace will be lost upon entering to
> > D3 cold hence user space app need to handle this situation.
> > 
> > v2:
> >   - s/(uval == 1) ? true : false/!!uval/ (Daniele)
> > v3:
> >   - Refine the commit message (Daniele)
> > 
> > Acked-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > Signed-off-by: Badal Nilawar <badal.nilawar at intel.com>
> > Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> 
> Bit of a flyby comment here, but would it be better if this was
> configfs rather than debugfs in case we wanted to skip this on the
> first probe?

Indeed. Configfs seems the best alternative for this. Otherwise
by the time we get to have the debugfs, the fw was already
attempted to get loaded at least once.

> 
> Thanks,
> Stuart
> 
> > ---
> >  drivers/gpu/drm/xe/xe_debugfs.c            | 41
> > ++++++++++++++++++++++
> >  drivers/gpu/drm/xe/xe_late_bind_fw.c       |  3 ++
> >  drivers/gpu/drm/xe/xe_late_bind_fw_types.h |  2 ++
> >  3 files changed, 46 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_debugfs.c
> > b/drivers/gpu/drm/xe/xe_debugfs.c
> > index d83cd6ed3fa8..d1f6f556efa2 100644
> > --- a/drivers/gpu/drm/xe/xe_debugfs.c
> > +++ b/drivers/gpu/drm/xe/xe_debugfs.c
> > @@ -226,6 +226,44 @@ static const struct file_operations
> > atomic_svm_timeslice_ms_fops = {
> >         .write = atomic_svm_timeslice_ms_set,
> >  };
> >  
> > +static ssize_t disable_late_binding_show(struct file *f, char __user
> > *ubuf,
> > +                                        size_t size, loff_t *pos)
> > +{
> > +       struct xe_device *xe = file_inode(f)->i_private;
> > +       struct xe_late_bind *late_bind = &xe->late_bind;
> > +       char buf[32];
> > +       int len;
> > +
> > +       len = scnprintf(buf, sizeof(buf), "%d\n", late_bind-
> > >disable);
> > +
> > +       return simple_read_from_buffer(ubuf, size, pos, buf, len);
> > +}
> > +
> > +static ssize_t disable_late_binding_set(struct file *f, const char
> > __user *ubuf,
> > +                                       size_t size, loff_t *pos)
> > +{
> > +       struct xe_device *xe = file_inode(f)->i_private;
> > +       struct xe_late_bind *late_bind = &xe->late_bind;
> > +       u32 uval;
> > +       ssize_t ret;
> > +
> > +       ret = kstrtouint_from_user(ubuf, size, sizeof(uval), &uval);
> > +       if (ret)
> > +               return ret;
> > +
> > +       if (uval > 1)
> > +               return -EINVAL;
> > +
> > +       late_bind->disable = !!uval;
> > +       return size;
> > +}
> > +
> > +static const struct file_operations disable_late_binding_fops = {
> > +       .owner = THIS_MODULE,
> > +       .read = disable_late_binding_show,
> > +       .write = disable_late_binding_set,
> > +};
> > +
> >  void xe_debugfs_register(struct xe_device *xe)
> >  {
> >         struct ttm_device *bdev = &xe->ttm;
> > @@ -249,6 +287,9 @@ void xe_debugfs_register(struct xe_device *xe)
> >         debugfs_create_file("atomic_svm_timeslice_ms", 0600, root,
> > xe,
> >                             &atomic_svm_timeslice_ms_fops);
> >  
> > +       debugfs_create_file("disable_late_binding", 0600, root, xe,
> > +                           &disable_late_binding_fops);
> > +
> >         for (mem_type = XE_PL_VRAM0; mem_type <= XE_PL_VRAM1;
> > ++mem_type) {
> >                 man = ttm_manager_type(bdev, mem_type);
> >  
> > diff --git a/drivers/gpu/drm/xe/xe_late_bind_fw.c
> > b/drivers/gpu/drm/xe/xe_late_bind_fw.c
> > index df43523e9043..88355adce1d0 100644
> > --- a/drivers/gpu/drm/xe/xe_late_bind_fw.c
> > +++ b/drivers/gpu/drm/xe/xe_late_bind_fw.c
> > @@ -167,6 +167,9 @@ int xe_late_bind_fw_load(struct xe_late_bind
> > *late_bind)
> >         if (!late_bind->component_added)
> >                 return -ENODEV;
> >  
> > +       if (late_bind->disable)
> > +               return 0;
> > +
> >         for (fw_id = 0; fw_id < XE_LB_FW_MAX_ID; fw_id++) {
> >                 lbfw = &late_bind->late_bind_fw[fw_id];
> >                 if (lbfw->payload) {
> > diff --git a/drivers/gpu/drm/xe/xe_late_bind_fw_types.h
> > b/drivers/gpu/drm/xe/xe_late_bind_fw_types.h
> > index 5c0574aff7b9..158dc1abe072 100644
> > --- a/drivers/gpu/drm/xe/xe_late_bind_fw_types.h
> > +++ b/drivers/gpu/drm/xe/xe_late_bind_fw_types.h
> > @@ -65,6 +65,8 @@ struct xe_late_bind {
> >         struct workqueue_struct *wq;
> >         /** @component_added: whether the component has been added */
> >         bool component_added;
> > +       /** @disable: to block late binding reload during pm resume
> > flow*/
> > +       bool disable;
> >  };
> >  
> >  #endif
>