[PATCH v2 3/8] drm/xe/debugfs: add page size allocation mode knob

[Nareshkumar Gollakoti <naresh.kumar.g@intel.com>]

Expose a debugfs control to override the page-size allocation mode used
for user BOs.

The interface allows switching between forced 2M, forced 1G, and mixed
allocation modes at runtime on platforms that support page-size
allocation control. This provides a simple way to validate behavior and
debug page-size-dependent allocation flows.

v2
- set cur_index using atomic_set as cur_index updated as atomic value
(sashiko)

Signed-off-by: Nareshkumar Gollakoti <naresh.kumar.g@intel.com>
---
 drivers/gpu/drm/xe/xe_debugfs.c | 52 +++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
index 22b471303984..2fa9ce04f9cd 100644
--- a/drivers/gpu/drm/xe/xe_debugfs.c
+++ b/drivers/gpu/drm/xe/xe_debugfs.c
@@ -544,6 +544,55 @@ static const struct file_operations disable_late_binding_fops = {
 	.write = disable_late_binding_set,
 };
 
+static ssize_t page_size_alloc_mode_show(struct file *f, char __user *ubuf,
+					 size_t size, loff_t *pos)
+{
+	struct xe_device *xe = file_inode(f)->i_private;
+	char buf[32];
+	int len;
+
+	if (!xe_device_supports_multi_pagesize(xe))
+		return -EOPNOTSUPP;
+
+	enum xe_page_size_alloc_ctrl_mode mode =
+		READ_ONCE(xe->page_size_alloc_ctrl.mode);
+	len = scnprintf(buf, sizeof(buf), "%d\n", mode);
+
+	return simple_read_from_buffer(ubuf, size, pos, buf, len);
+}
+
+static ssize_t page_size_alloc_mode_set(struct file *f, const char __user *ubuf,
+					size_t size, loff_t *pos)
+{
+	struct xe_device *xe = file_inode(f)->i_private;
+	unsigned int val;
+	int ret;
+
+	if (!xe_device_supports_multi_pagesize(xe))
+		return -EOPNOTSUPP;
+
+	ret = kstrtouint_from_user(ubuf, size, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val > XE_PAGE_SIZE_ALLOC_CTRL_MODE_MIXED)
+		return -EINVAL;
+
+	WRITE_ONCE(xe->page_size_alloc_ctrl.mode,
+		   (enum xe_page_size_alloc_ctrl_mode)val);
+
+	if (val == XE_PAGE_SIZE_ALLOC_CTRL_MODE_MIXED)
+		atomic_set(&xe->page_size_alloc_ctrl.cur_index, 0);
+
+	return size;
+}
+
+static const struct file_operations page_size_alloc_mode_fops = {
+	.owner = THIS_MODULE,
+	.read = page_size_alloc_mode_show,
+	.write = page_size_alloc_mode_set,
+};
+
 void xe_debugfs_register(struct xe_device *xe)
 {
 	struct ttm_device *bdev = &xe->ttm;
@@ -585,6 +634,9 @@ void xe_debugfs_register(struct xe_device *xe)
 	debugfs_create_file("disable_late_binding", 0600, root, xe,
 			    &disable_late_binding_fops);
 
+	debugfs_create_file("page_size_alloc_mode", 0600, root, xe,
+			    &page_size_alloc_mode_fops);
+
 	/*
 	 * Don't expose page reclaim configuration file if not supported by the
 	 * hardware initially.
-- 
2.43.0