Re: [PATCH 03/11] drm: add driver for simple vga encoders

Hi Heiko,

Thank you for the patch.

On Saturday 31 January 2015 17:32:56 Heiko Stuebner wrote:

There exist simple vga encoders without any type of management interface and just maybe a simple gpio for turning it on or off. Examples for these are the Analog Devices ADV7123, Chipsea CS7123 or Micronas SDA7123.

Add a generic encoder driver for those that can be used by drm drivers using the component framework.

The rcar-du driver already handles the adi,adv7123 compatible string used by this driver. A generic driver is in my opinion a very good idea, but we can't break the existing support. Porting the rcar-du driver to the component model is needed.

Signed-off-by: Heiko Stuebner heiko@sntech.de

drivers/gpu/drm/i2c/Kconfig | 6 + drivers/gpu/drm/i2c/Makefile | 2 + drivers/gpu/drm/i2c/vga-simple.c | 325 ++++++++++++++++++++++++++++++++++++

drivers/gpu/drm/i2c/ feels wrong for a platform device.

3 files changed, 333 insertions(+) create mode 100644 drivers/gpu/drm/i2c/vga-simple.c

diff --git a/drivers/gpu/drm/i2c/Kconfig b/drivers/gpu/drm/i2c/Kconfig index 22c7ed6..319f2cb 100644 --- a/drivers/gpu/drm/i2c/Kconfig +++ b/drivers/gpu/drm/i2c/Kconfig @@ -31,4 +31,10 @@ config DRM_I2C_NXP_TDA998X help Support for NXP Semiconductors TDA998X HDMI encoders.

+config DRM_VGA_SIMPLE

• tristate "Generic simple vga encoder"
• help

•  Support for vga encoder chips without any special settings
  

•  and at most a power-control gpio.
  

endmenu diff --git a/drivers/gpu/drm/i2c/Makefile b/drivers/gpu/drm/i2c/Makefile index 2c72eb5..858961f 100644 --- a/drivers/gpu/drm/i2c/Makefile +++ b/drivers/gpu/drm/i2c/Makefile @@ -10,3 +10,5 @@ obj-$(CONFIG_DRM_I2C_SIL164) += sil164.o

tda998x-y := tda998x_drv.o obj-$(CONFIG_DRM_I2C_NXP_TDA998X) += tda998x.o

+obj-$(CONFIG_DRM_VGA_SIMPLE) += vga-simple.o diff --git a/drivers/gpu/drm/i2c/vga-simple.c b/drivers/gpu/drm/i2c/vga-simple.c new file mode 100644 index 0000000..bb9d19c --- /dev/null +++ b/drivers/gpu/drm/i2c/vga-simple.c @@ -0,0 +1,325 @@ +/*

• • Simple vga encoder driver
• • Copyright (C) 2014 Heiko Stuebner heiko@sntech.de
• • This software is licensed under the terms of the GNU General Public
• • License version 2, as published by the Free Software Foundation, and
• • may be copied, distributed, and modified under those terms.
• • This program is distributed in the hope that it will be useful,
• • but WITHOUT ANY WARRANTY; without even the implied warranty of
• • MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• • GNU General Public License for more details.
• */

+#include <linux/module.h> +#include <linux/component.h> +#include <linux/gpio.h> +#include <linux/gpio/consumer.h> +#include <linux/i2c.h> +#include <linux/regulator/consumer.h> +#include <drm/drm_of.h> +#include <drm/drmP.h> +#include <drm/drm_crtc.h> +#include <drm/drm_crtc_helper.h> +#include <drm/drm_edid.h>

+#define connector_to_vga_simple(x) container_of(x, struct vga_simple, connector) +#define encoder_to_vga_simple(x) container_of(x, struct vga_simple, encoder) + +struct vga_simple {

• struct drm_connector connector;
• struct drm_encoder encoder;
• struct device *dev;
• struct i2c_adapter *ddc;
• struct regulator *vaa_reg;
• struct gpio_desc *enable_gpio;
• struct mutex enable_lock;
• bool enabled;

+};

+/*

• • Connector functions
• */

+enum drm_connector_status vga_simple_detect(struct drm_connector *connector, + bool force) +{

• struct vga_simple *vga = connector_to_vga_simple(connector);
• if (!vga->ddc)

• return connector_status_unknown;
  

• if (drm_probe_ddc(vga->ddc))

• return connector_status_connected;
  

• return connector_status_disconnected;

+}

+void vga_simple_connector_destroy(struct drm_connector *connector) +{

• drm_connector_unregister(connector);
• drm_connector_cleanup(connector);

+}

+struct drm_connector_funcs vga_simple_connector_funcs = {

• .dpms = drm_helper_connector_dpms,
• .fill_modes = drm_helper_probe_single_connector_modes,
• .detect = vga_simple_detect,
• .destroy = vga_simple_connector_destroy,

+};

+/*

• • Connector helper functions
• */

+static int vga_simple_connector_get_modes(struct drm_connector *connector) +{

• struct vga_simple *vga = connector_to_vga_simple(connector);
• struct edid *edid;
• int ret = 0;
• if (!vga->ddc)

• return 0;
  

• edid = drm_get_edid(connector, vga->ddc);
• if (edid) {

• drm_mode_connector_update_edid_property(connector, edid);
  

• ret = drm_add_edid_modes(connector, edid);
  

• kfree(edid);
  

• }
• return ret;

+}

+static int vga_simple_connector_mode_valid(struct drm_connector *connector,

• 			struct drm_display_mode *mode)
  

+{

• return MODE_OK;

+}

+static struct drm_encoder +*vga_simple_connector_best_encoder(struct drm_connector *connector) +{

• struct vga_simple *vga = connector_to_vga_simple(connector);
• return &vga->encoder;

+}

+static struct drm_connector_helper_funcs vga_simple_connector_helper_funcs = { + .get_modes = vga_simple_connector_get_modes,

• .best_encoder = vga_simple_connector_best_encoder,
• .mode_valid = vga_simple_connector_mode_valid,

+};

+/*

• • Encoder functions
• */

+static void vga_simple_encoder_destroy(struct drm_encoder *encoder) +{

• drm_encoder_cleanup(encoder);

+}

+static const struct drm_encoder_funcs vga_simple_encoder_funcs = {

• .destroy = vga_simple_encoder_destroy,

+};

+/*

• • Encoder helper functions
• */

+static void vga_simple_encoder_dpms(struct drm_encoder *encoder, int mode) +{

• struct vga_simple *vga = encoder_to_vga_simple(encoder);
• mutex_lock(&vga->enable_lock);
• switch (mode) {
• case DRM_MODE_DPMS_ON:

• if (vga->enabled)
  

• 	goto out;
  

• if (!IS_ERR(vga->vaa_reg))
  

• 	regulator_enable(vga->vaa_reg);
  

• if (vga->enable_gpio)
  

• 	gpiod_set_value(vga->enable_gpio, 1);
  

• vga->enabled = true;
  

• break;
  

• case DRM_MODE_DPMS_STANDBY:
• case DRM_MODE_DPMS_SUSPEND:
• case DRM_MODE_DPMS_OFF:

• if (!vga->enabled)
  

• 	goto out;
  

• if (vga->enable_gpio)
  

• 	gpiod_set_value(vga->enable_gpio, 0);
  

• if (!IS_ERR(vga->vaa_reg))
  

• 	regulator_enable(vga->vaa_reg);
  

• vga->enabled = false;
  

• break;
  

• default:

• break;
  

• }

+out:

• mutex_unlock(&vga->enable_lock);

+}

+static bool vga_simple_mode_fixup(struct drm_encoder *encoder,

• 		  const struct drm_display_mode *mode,
  

• 		  struct drm_display_mode *adjusted_mode)
  

+{

• return true;

+}

+static void vga_simple_encoder_prepare(struct drm_encoder *encoder) +{ +}

+static void vga_simple_encoder_mode_set(struct drm_encoder *encoder,

• 			struct drm_display_mode *mode,
  

• 			struct drm_display_mode *adjusted_mode)
  

+{ +}

+static void vga_simple_encoder_commit(struct drm_encoder *encoder) +{

• vga_simple_encoder_dpms(encoder, DRM_MODE_DPMS_ON);

+}

+static void vga_simple_encoder_disable(struct drm_encoder *encoder) +{

• vga_simple_encoder_dpms(encoder, DRM_MODE_DPMS_OFF);

+}

+static const struct drm_encoder_helper_funcs vga_simple_encoder_helper_funcs = {

• .dpms = vga_simple_encoder_dpms,
• .mode_fixup = vga_simple_mode_fixup,
• .prepare = vga_simple_encoder_prepare,
• .mode_set = vga_simple_encoder_mode_set,
• .commit = vga_simple_encoder_commit,
• .disable = vga_simple_encoder_disable,

this is interesting. Some users of this encoder (I'm thinking about rcar-du, for which I've just posted the patches) are already ported to atomic updates, while others are not. How can we support both ?

+};

+/*

• • Component helper functions
• */

+static int vga_simple_bind(struct device *dev, struct device *master,

• 		 void *data)
  

+{

• struct platform_device *pdev = to_platform_device(dev);
• struct drm_device *drm = data;
• struct device_node *ddc_node, *np = pdev->dev.of_node;
• struct vga_simple *vga;
• int ret;
• if (!np)

• return -ENODEV;
  

• vga = devm_kzalloc(dev, sizeof(*vga), GFP_KERNEL);
• if (!vga)

• return -ENOMEM;
  

• vga->dev = dev;
• dev_set_drvdata(dev, vga);
• mutex_init(&vga->enable_lock);
• vga->enable_gpio = devm_gpiod_get_optional(dev, "enable",

• 				   GPIOD_OUT_LOW);
  

• if (IS_ERR(vga->enable_gpio)) {

• ret = PTR_ERR(vga->enable_gpio);
  

• dev_err(dev, "failed to request GPIO: %d\n", ret);
  

• return ret;
  

• }
• vga->enabled = false;
• ddc_node = of_parse_phandle(np, "ddc-i2c-bus", 0);
• if (ddc_node) {

• vga->ddc = of_find_i2c_adapter_by_node(ddc_node);
  

• of_node_put(ddc_node);
  

• if (!vga->ddc) {
  

• 	dev_dbg(vga->dev, "failed to read ddc node\n");
  

• 	return -EPROBE_DEFER;
  

• }
  

• } else {

• dev_dbg(vga->dev, "no ddc property found\n");
  

• }
• vga->vaa_reg = devm_regulator_get_optional(dev, "vaa");
• vga->encoder.possible_crtcs = drm_of_find_possible_crtcs(drm, np);
• vga->encoder.of_node = np;
• vga->connector.polled = DRM_CONNECTOR_POLL_CONNECT |

• 		DRM_CONNECTOR_POLL_DISCONNECT;
  

• drm_encoder_helper_add(&vga->encoder, &vga_simple_encoder_helper_funcs);
• drm_encoder_init(drm, &vga->encoder, &vga_simple_encoder_funcs,

• 	 DRM_MODE_ENCODER_DAC);
  

• drm_connector_helper_add(&vga->connector,

• 		 &vga_simple_connector_helper_funcs);
  

I really dislike this, this is an encoder driver, not a connector driver. It shouldn't be responsible for creating the connector. For all it knows, there might not even be a VGA connector connected to the encoder, VGA signals could be sent to a chained encoder. That might be a bit far-fetched in the VGA case, but in the generic case encoder drivers shouldn't create connectors.

• drm_connector_init(drm, &vga->connector, &vga_simple_connector_funcs,

• 	   DRM_MODE_CONNECTOR_VGA);
  

• drm_mode_connector_attach_encoder(&vga->connector, &vga->encoder);
• return 0;

+}

+static void vga_simple_unbind(struct device *dev, struct device *master,

• 		    void *data)
  

+{

• struct vga_simple *vga = dev_get_drvdata(dev);
• vga->connector.funcs->destroy(&vga->connector);
• vga->encoder.funcs->destroy(&vga->encoder);

+}

+static const struct component_ops vga_simple_ops = {

• .bind = vga_simple_bind,
• .unbind = vga_simple_unbind,

+};

+static int vga_simple_probe(struct platform_device *pdev) +{

• return component_add(&pdev->dev, &vga_simple_ops);

+}

+static int vga_simple_remove(struct platform_device *pdev) +{

• component_del(&pdev->dev, &vga_simple_ops);
• return 0;

+}

+static const struct of_device_id vga_simple_ids[] = {

• { .compatible = "adi,adv7123", },
• {},

+}; +MODULE_DEVICE_TABLE(of, vga_simple_ids);

+static struct platform_driver vga_simple_driver = {

• .probe = vga_simple_probe,
• .remove = vga_simple_remove,
• .driver = {

• .name = "vga-simple",
  

• .of_match_table = vga_simple_ids,
  

• },

+}; +module_platform_driver(vga_simple_driver);

+MODULE_AUTHOR("Heiko Stuebner heiko@sntech.de"); +MODULE_DESCRIPTION("Simple vga converter"); +MODULE_LICENSE("GPL");