drm: Add panel support

Add a very simple framework to register and lookup panels. Panel drivers can initialize a DRM panel and register it with the framework, allowing them to be retrieved and used by display drivers. Currently only support for DPMS and obtaining panel modes is provided. However it should be sufficient to enable a large number of panels. The framework should also be easily extensible to support more sophisticated kinds of panels such as DSI.

The framework hasn't been tied into the DRM core, even though it should be easily possible to do so if that's what we want. In the current implementation, display drivers can simple make use of it to retrieve a panel, obtain its modes and control its DPMS mode.

Note that this is currently only tested on systems that boot from a device tree. No glue code has been written yet for systems that use platform data, but it should be easy to add.

Signed-off-by Thierry Reding <[email protected]>

---
  drivers/gpu/drm/Kconfig       |  2 +
  drivers/gpu/drm/Makefile      |  1 +
  drivers/gpu/drm/drm_panel.c   | 96 +++++++++++++++++++++++++++++++++++++++++++
  drivers/gpu/drm/panel/Kconfig |  4 ++
  include/drm/drm_panel.h       | 65 +++++++++++++++++++++++++++++
  5 files changed, 168 insertions(+)

create mode 100644 drivers/gpu/drm/drm_panel.c create mode 100644 drivers/gpu/drm/panel/Kconfig create mode 100644 include/drm/drm_panel.h

drivers/gpu/drm/Kconfig +2 -0

index 955555d..b4d8402 100644
@@ -236,3 +236,5 @@ source "drivers/gpu/drm/tilcdc/Kconfig"
  source "drivers/gpu/drm/qxl/Kconfig"
 
  source "drivers/gpu/drm/msm/Kconfig"
+
+source "drivers/gpu/drm/panel/Kconfig"

drivers/gpu/drm/Makefile +1 -0

index f089adf..9b009c7 100644
@@ -18,6 +18,7 @@ drm-y       :=        drm_auth.o drm_buffer.o drm_bufs.o drm_cache.o \
  drm-$(CONFIG_COMPAT) += drm_ioc32.o
  drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o
  drm-$(CONFIG_PCI) += ati_pcigart.o
+drm-$(CONFIG_DRM_PANEL) += drm_panel.o
 
  drm-usb-y   := drm_usb.o
 

drivers/gpu/drm/drm_panel.c new file +53 -0

new file mode 100644
index 0000000..ff6e459
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2013, NVIDIA Corporation.  All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/err.h>
+#include <linux/export.h>
+
+#include <drm/drm_crtc.h>
+#include <drm/drm_panel.h>
+
+static DEFINE_MUTEX(panel_lock);
+static LIST_HEAD(panel_list);
+
+void drm_panel_init(struct drm_panel *panel)
+{
+       INIT_LIST_HEAD(&panel->list);
+}
+EXPORT_SYMBOL(drm_panel_init);
+
+int drm_panel_add(struct drm_panel *panel)
+{
+       mutex_lock(&panel_lock);
+       list_add_tail(&panel->list, &panel_list);
+       mutex_unlock(&panel_lock);
+
+       return 0;
+}
+EXPORT_SYMBOL(drm_panel_add);
+
+void drm_panel_remove(struct drm_panel *panel)
+{
+       mutex_lock(&panel_lock);
+       list_del_init(&panel->list);
+       mutex_unlock(&panel_lock);

drivers/gpu/drm/drm_panel.c new file +33 -0

+
+       return 0;
+}
+EXPORT_SYMBOL(drm_panel_attach);
+
+int drm_panel_detach(struct drm_panel *panel)
+{
+       panel->connector = NULL;
+       panel->drm = NULL;
+
+       return 0;
+}
+EXPORT_SYMBOL(drm_panel_detach);
+
+#ifdef CONFIG_OF
+struct drm_panel *of_drm_find_panel(struct device_node *np)
+{
+       struct drm_panel *panel;
+
+       mutex_lock(&panel_lock);
+
+       list_for_each_entry(panel, &panel_list, list) {
+               if (panel->dev->of_node == np) {
+                       mutex_unlock(&panel_lock);
+                       return panel;
+               }
+       }
+
+       mutex_unlock(&panel_lock);
+       return NULL;
+}
+EXPORT_SYMBOL(of_drm_find_panel);
+#endif

drivers/gpu/drm/panel/Kconfig new file +4 -0

new file mode 100644
index 0000000..2ddd5bd
@@ -0,0 +1,4 @@
+menuconfig DRM_PANEL
+       bool "DRM panel support"
+       help
+         Panel registration and lookup framework.

include/drm/drm_panel.h new file +65 -1

new file mode 100644
index 0000000..f02b615
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2013, NVIDIA Corporation.  All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef __DRM_PANEL_H__
+#define __DRM_PANEL_H__
+
+#include <linux/list.h>
+
+struct drm_connector;
+struct drm_device;
+struct drm_panel;
+
+struct drm_panel_funcs {
+       void (*dpms)(struct drm_panel *panel, int mode);
+       int (*get_modes)(struct drm_panel *panel);
+};
+
+struct drm_panel {
+       struct drm_device *drm;
+       struct drm_connector *connector;
+       struct device *dev;
+
+       const struct drm_panel_funcs *funcs;
+
+       struct list_head list;
+};
+
+void drm_panel_init(struct drm_panel *panel);
+
+int drm_panel_add(struct drm_panel *panel);
+void drm_panel_remove(struct drm_panel *panel);
+
+int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector);
+int drm_panel_detach(struct drm_panel *panel);
+
+#ifdef CONFIG_OF
+struct drm_panel *of_drm_find_panel(struct device_node *np);
+#else
+static inline struct drm_panel *of_drm_find_panel(struct device_node *np)
+{
+       return NULL;
+}
+#endif
+
+#endif
--

1.8.4

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Add a driver for simple panels. Such panels can have a regulator that provides the supply voltage and a separate GPIO to enable the panel. Optionally the panels can have a backlight associated with them so it can be enabled or disabled according to the panel's power management mode.

Support is added for three panels: An AU Optronics 10.1" WSVGA, a Chunghwa Picture Tubes 10.1" WXGA and a Panasonic 10.1 WUXGA TFT LCD panel.

Signed-off-by Thierry Reding <[email protected]>

---

.../devicetree/bindings/panel/panel-simple.txt     |  25 ++
drivers/gpu/drm/Makefile                           |   1 +
drivers/gpu/drm/panel/Kconfig                      |  13 +
drivers/gpu/drm/panel/Makefile                     |   1 +
drivers/gpu/drm/panel/panel-simple.c               | 335 +++++++++++++++++++++
5 files changed, 375 insertions(+)

create mode 100644 Documentation/devicetree/bindings/panel/panel-simple.txt create mode 100644 drivers/gpu/drm/panel/Makefile
create mode 100644 drivers/gpu/drm/panel/panel-simple.c

Documentation/devicetree/bindings/panel/panel-simple.txt new file +0 -0

new file mode 100644
index 0000000..dfd4b76

Quoted 11 lines · Thierry Reding

Add a driver for simple panels. Such panels can have a regulator that provides the supply voltage and a separate GPIO to enable the panel. Optionally the panels can have a backlight associated with them so it can be enabled or disabled according to the panel's power management mode.

Support is added for three panels: An AU Optronics 10.1" WSVGA, a Chunghwa Picture Tubes 10.1" WXGA and a Panasonic 10.1 WUXGA TFT LCD panel.

Documentation/devicetree/bindings/panel/panel-simple.txt +0 -0

Documentation/devicetree/bindings/panel/panel-simple.txt line 8

Quoted 6 lines

Documentation/devicetree/bindings/panel/panel-simple.txt +6 -0

+Required properties:
+- compatible: should be one of:
+  - "auo,b101aw03": AU Optronics Corporation 10.1" WSVGA TFT LCD panel
+  - "cptt,claa101wb03": Chunghwa Picture Tubes Ltd. 10.1" WXGA TFT LCD panel
+  - "pc,vvx10f004b00": Panasonic Corporation 10.1" WUXGA TFT LCD panel
+

It would seem there should be a more generic compatible to cover the basic "panel-simple" case.

Documentation/devicetree/bindings/panel/panel-simple.txt line 14

Quoted 6 lines

Documentation/devicetree/bindings/panel/panel-simple.txt +6 -0

+Optional properties:
+- ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
+- power-supply: regulator to provide the supply voltage
+- enable-gpios: GPIO pin to enable or disable the panel
+- backlight: phandle of the backlight device attached to the panel
+

If these are all optional, what does it mean to be a "panel-simple"?

Add a driver for simple panels. Such panels can have a regulator that provides the supply voltage and a separate GPIO to enable the panel. Optionally the panels can have a backlight associated with them so it can be enabled or disabled according to the panel's power management mode.

Documentation/devicetree/bindings/panel/panel-simple.txt +3 -0

 
+Simple display panel
+
+Required properties:

Quoted 17 lines · Thierry Reding

Add a driver for simple panels. Such panels can have a regulator that provides the supply voltage and a separate GPIO to enable the panel. Optionally the panels can have a backlight associated with them so it can be enabled or disabled according to the panel's power management mode.

Documentation/devicetree/bindings/panel/panel-simple.txt +9 -0

 
+Simple display panel
+
+Required properties:
+- compatible: should be one of:
+  - "auo,b101aw03": AU Optronics Corporation 10.1" WSVGA TFT LCD panel
+  - "cptt,claa101wb03": Chunghwa Picture Tubes Ltd. 10.1" WXGA TFT LCD panel
+  - "pc,vvx10f004b00": Panasonic Corporation 10.1" WUXGA TFT LCD panel
+
+Optional properties:

Quoted 4 lines

+- ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
+- power-supply: regulator to provide the supply voltage
+- enable-gpios: GPIO pin to enable or disable the panel
+- backlight: phandle of the backlight device attached to the panel

Do we need to represent the timing requirements e.g. between panel enable and backlight enable, or do you expect the driver to hard-code this based on the compatible value?

Looking at the driver code, it seems that it has direct knowledge of the video mode that each panel supports, so DDC is actually optional unlike what I asserted/assumed in my previous response. As such, I guess we should have a separate DT binding document for each of the three panels (compatible values) listed above that pretty much just says "go look at simple-panel.txt".