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

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Message-ID: <1f323cf45af3ba781d46d2e889f89bc26aa9b85a.camel@intel.com>
Date: Thu, 31 Jul 2025 20:03:36 +0000
From: "Summers, Stuart" <stuart.summers@...el.com>
To: "intel-xe@...ts.freedesktop.org" <intel-xe@...ts.freedesktop.org>, "Vivi,
 Rodrigo" <rodrigo.vivi@...el.com>, "dri-devel@...ts.freedesktop.org"
	<dri-devel@...ts.freedesktop.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: "Nilawar, Badal" <badal.nilawar@...el.com>, "gregkh@...uxfoundation.org"
	<gregkh@...uxfoundation.org>, "Usyskin, Alexander"
	<alexander.usyskin@...el.com>, "Ceraolo Spurio, Daniele"
	<daniele.ceraolospurio@...el.com>, "Gupta, Anshuman"
	<anshuman.gupta@...el.com>
Subject: Re: [PATCH 8/9] drm/xe/xe_late_bind_fw: Introduce debug fs node to
 disable late binding

On Thu, 2025-07-10 at 11:08 -0400, Rodrigo Vivi wrote:
> From: Badal Nilawar <badal.nilawar@...el.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@...el.com>
> Signed-off-by: Badal Nilawar <badal.nilawar@...el.com>
> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@...el.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?

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