Documentation/amdgpu: Add UMA carveout details

Add documentation for the uma/carveout_options and uma/carveout
attributes in sysfs

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Yo-Jung Leo Lin (AMD) <Leo.Lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/Documentation/gpu/amdgpu/driver-misc.rst b/Documentation/gpu/amdgpu/driver-misc.rst
index 25b0c857816ea0b02a1b11c7c2cad13d4fdaf35e..e1a964c3add2aed19761a6e546d18e4a3f2d5b9a 100644 (file)
--- a/Documentation/gpu/amdgpu/driver-misc.rst
+++ b/Documentation/gpu/amdgpu/driver-misc.rst
@@ -128,3 +128,29 @@ smartshift_bias
 
 .. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
    :doc: smartshift_bias
+
+UMA Carveout
+============
+
+Some versions of Atom ROM expose available options for the VRAM carveout sizes,
+and allow changes to the carveout size via the ATCS function code 0xA on supported
+BIOS implementations.
+
+For those platforms, users can use the following files under uma/ to set the
+carveout size, in a way similar to what Windows users can do in the "Tuning"
+tab in AMD Adrenalin.
+
+Note that for BIOS implementations that don't support this, these files will not
+be created at all.
+
+uma/carveout_options
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: uma/carveout_options
+
+uma/carveout
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: uma/carveout

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 96842b04137254f8fd9562578faa46408f0e64b7..6378926f1aeb7166d64abbfb2ed8f4b6da4f5d5e 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -382,6 +382,24 @@ static const struct attribute_group amdgpu_board_attrs_group = {
        .is_visible = amdgpu_board_attrs_is_visible
 };
 
+/**
+ * DOC: uma/carveout_options
+ *
+ * This is a read-only file that lists all available UMA allocation
+ * options and their corresponding indices. Example output::
+ *
+ *     $ cat uma/carveout_options
+ *     0: Minimum (512 MB)
+ *     1:  (1 GB)
+ *     2:  (2 GB)
+ *     3:  (4 GB)
+ *     4:  (6 GB)
+ *     5:  (8 GB)
+ *     6:  (12 GB)
+ *     7: Medium (16 GB)
+ *     8:  (24 GB)
+ *     9: High (32 GB)
+ */
 static ssize_t carveout_options_show(struct device *dev,
                                     struct device_attribute *attr,
                                     char *buf)
@@ -414,6 +432,17 @@ static ssize_t carveout_options_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(carveout_options);
 
+/**
+ * DOC: uma/carveout
+ *
+ * This file is both readable and writable. When read, it shows the
+ * index of the current setting. Writing a valid index to this file
+ * allows users to change the UMA carveout size to the selected option
+ * on the next boot.
+ *
+ * The available options and their corresponding indices can be read
+ * from the uma/carveout_options file.
+ */
 static ssize_t carveout_show(struct device *dev,
                             struct device_attribute *attr,
                             char *buf)