Re: [PATCH V2 3/4] drm/bridge: Drivers for megachips-stdpxxxx-ge-b850v3-fw (LVDS-DP++)

Hi Peter,

On 3/1/2017 4:08 PM, Peter Senna Tschudin wrote:

Hi Archit,

Thank you for the review!

On Wed, Mar 01, 2017 at 09:38:48AM +0530, Archit Taneja wrote:

...

On 02/28/2017 07:58 PM, Peter Senna Tschudin wrote:

...

The video processing pipeline on the second output on the GE B850v3:

Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output

Each bridge has a dedicated flash containing firmware for supporting the custom design. The result is that in this design neither the STDP4028 nor the STDP2690 behave as the stock bridges would. The compatible strings include the suffix "-ge-b850v3-fw" to make it clear that the driver is for the bridges with the firmware which is specific for the GE B850v3.

The driver is powerless to control the video processing pipeline, as the two bridges behaves as a single one. The driver is only needed for telling the host about EDID / HPD, and for giving the host powers to ack interrupts.

This driver adds one i2c_device for each bridge, but only one drm_bridge. This design allows the creation of a functional connector that is capable of reading EDID from the STDP2690 while handling interrupts on the STDP4028.

Cc: Laurent Pinchart laurent.pinchart@ideasonboard.com Cc: Martyn Welch martyn.welch@collabora.co.uk Cc: Martin Donnelly martin.donnelly@ge.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Enric Balletbo i Serra enric.balletbo@collabora.com Cc: Philipp Zabel p.zabel@pengutronix.de Cc: Rob Herring robh@kernel.org Cc: Fabio Estevam fabio.estevam@nxp.com Cc: David Airlie airlied@linux.ie Cc: Thierry Reding treding@nvidia.com Cc: Thierry Reding thierry.reding@gmail.com Cc: Archit Taneja architt@codeaurora.org Cc: Enric Balletbo enric.balletbo@collabora.com Signed-off-by: Peter Senna Tschudin peter.senna@collabora.com

---

Changes from V1:

• Updated copyright year
• Fixed blank line issues
• Updated ge_b850v3_lvds_remove() to not rely on ge_b850v3_lvds_ptr->edid and added a comment to explain the test.
• Fixed checkpatch strict warnings about continuation lines. In one case fixing the warning would cause the continuation line to be over 80 chars and that strict warning remains.

drivers/gpu/drm/bridge/Kconfig | 11 + drivers/gpu/drm/bridge/Makefile | 1 + .../drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c | 411 +++++++++++++++++++++ 3 files changed, 423 insertions(+) create mode 100644 drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig index eb8688e..4a937f1 100644 --- a/drivers/gpu/drm/bridge/Kconfig +++ b/drivers/gpu/drm/bridge/Kconfig @@ -48,6 +48,17 @@ config DRM_DW_HDMI_I2S_AUDIO Support the I2S Audio interface which is part of the Synopsis Designware HDMI block.

+config DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW

• tristate "MegaChips stdp4028-ge-b850v3-fw and stdp2690-ge-b850v3-fw"
• depends on OF
• select DRM_KMS_HELPER
• select DRM_PANEL
• ---help---

•      This is a driver for the display bridges of
  

•      GE B850v3 that convert dual channel LVDS
  

•      to DP++. This is used with the i.MX6 imx-ldb
  

•      driver. You are likely to say N here.
  

config DRM_NXP_PTN3460 tristate "NXP PTN3460 DP/LVDS bridge" depends on OF diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile index 2e83a785..af0b7cc 100644 --- a/drivers/gpu/drm/bridge/Makefile +++ b/drivers/gpu/drm/bridge/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_DRM_DUMB_VGA_DAC) += dumb-vga-dac.o obj-$(CONFIG_DRM_DW_HDMI) += dw-hdmi.o obj-$(CONFIG_DRM_DW_HDMI_AHB_AUDIO) += dw-hdmi-ahb-audio.o obj-$(CONFIG_DRM_DW_HDMI_I2S_AUDIO) += dw-hdmi-i2s-audio.o +obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o diff --git a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c new file mode 100644 index 0000000..6f82a44 --- /dev/null +++ b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c @@ -0,0 +1,411 @@ +/*

• • Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
• • Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)
• • Copyright (c) 2017, Collabora Ltd.
• • Copyright (c) 2017, General Electric Company
• • This program is free software; you can redistribute it and/or modify it
• • under the terms and conditions of the GNU General Public License,
• • version 2, as published by the Free Software Foundation.
• • This program is distributed in the hope 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.
• • You should have received a copy of the GNU General Public License
• • along with this program. If not, see http://www.gnu.org/licenses/.
• • This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
• • display bridge of the GE B850v3. There are two physical bridges on the video
• • signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
• • physical bridges are automatically configured by the input video signal, and
• • the driver has no access to the video processing pipeline. The driver is
• • only needed to read EDID from the STDP2690 and to handle HPD events from the
• • STDP4028. The driver communicates with both bridges over i2c. The video
• • signal pipeline is as follows:
• • Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
• */

+#include <linux/gpio.h> +#include <linux/i2c.h> +#include <linux/module.h> +#include <linux/of.h> +#include <drm/drm_atomic.h> +#include <drm/drm_atomic_helper.h> +#include <drm/drm_crtc_helper.h> +#include <drm/drm_edid.h> +#include <drm/drmP.h>

+#define EDID_EXT_BLOCK_CNT 0x7E

+#define STDP4028_IRQ_OUT_CONF_REG 0x02 +#define STDP4028_DPTX_IRQ_EN_REG 0x3C +#define STDP4028_DPTX_IRQ_STS_REG 0x3D +#define STDP4028_DPTX_STS_REG 0x3E

+#define STDP4028_DPTX_DP_IRQ_EN 0x1000

+#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400 +#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000 +#define STDP4028_DPTX_IRQ_CONFIG \

• (STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)
  

+#define STDP4028_DPTX_HOTPLUG_STS 0x0200 +#define STDP4028_DPTX_LINK_STS 0x1000 +#define STDP4028_CON_STATE_CONNECTED \

• (STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)
  

+#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400 +#define STDP4028_DPTX_LINK_CH_STS 0x2000 +#define STDP4028_DPTX_IRQ_CLEAR \

• (STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)
  

+static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);

+struct ge_b850v3_lvds {

• struct drm_connector connector;
• struct drm_bridge bridge;
• struct i2c_client *stdp4028_i2c;
• struct i2c_client *stdp2690_i2c;
• struct edid *edid;

+};

+static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;

+u8 *stdp2690_get_edid(struct i2c_client *client) +{

• struct i2c_adapter *adapter = client->adapter;
• unsigned char start = 0x00;
• unsigned int total_size;
• u8 *block = kmalloc(EDID_LENGTH, GFP_KERNEL);
• struct i2c_msg msgs[] = {

• {
  

• 	.addr	= client->addr,
  

• 	.flags	= 0,
  

• 	.len	= 1,
  

• 	.buf	= &start,
  

• }, {
  

• 	.addr	= client->addr,
  

• 	.flags	= I2C_M_RD,
  

• 	.len	= EDID_LENGTH,
  

• 	.buf	= block,
  

• }
  

• };
• if (!block)

• return NULL;
  

• if (i2c_transfer(adapter, msgs, 2) != 2) {

• DRM_ERROR("Unable to read EDID.\n");
  

• goto err;
  

• }
• if (!drm_edid_block_valid(block, 0, false, NULL)) {

• DRM_ERROR("Invalid EDID data\n");
  

• goto err;
  

• }
• total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH;
• if (total_size > EDID_LENGTH) {

• kfree(block);
  

• block = kmalloc(total_size, GFP_KERNEL);
  

• if (!block)
  

• 	return NULL;
  

• /* Yes, read the entire buffer, and do not skip the first
  

•  * EDID_LENGTH bytes.
  

•  */
  

• start = 0x00;
  

• msgs[1].len = total_size;
  

• msgs[1].buf = block;
  

• if (i2c_transfer(adapter, msgs, 2) != 2) {
  

• 	DRM_ERROR("Unable to read EDID extension blocks.\n");
  

• 	goto err;
  

• }
  

• if (!drm_edid_block_valid(block, 1, false, NULL)) {
  

• 	DRM_ERROR("Invalid EDID data\n");
  

• 	goto err;
  

• }
  

• }
• return block;

+err:

• kfree(block);
• return NULL;

+}

+static int ge_b850v3_lvds_get_modes(struct drm_connector *connector) +{

• struct i2c_client *client;
• int num_modes = 0;
• client = ge_b850v3_lvds_ptr->stdp2690_i2c;
• kfree(ge_b850v3_lvds_ptr->edid);
• ge_b850v3_lvds_ptr->edid = (struct edid *)stdp2690_get_edid(client);
• if (ge_b850v3_lvds_ptr->edid) {

• drm_mode_connector_update_edid_property(connector,
  

• 				      ge_b850v3_lvds_ptr->edid);
  

• num_modes = drm_add_edid_modes(connector,
  

• 			       ge_b850v3_lvds_ptr->edid);
  

• }
• return num_modes;

+}

+static enum drm_mode_status ge_b850v3_lvds_mode_valid(

• struct drm_connector *connector, struct drm_display_mode *mode)
  

+{

• return MODE_OK;

+}

+static const struct +drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {

• .get_modes = ge_b850v3_lvds_get_modes,
• .mode_valid = ge_b850v3_lvds_mode_valid,

+};

+static enum drm_connector_status ge_b850v3_lvds_detect(

• struct drm_connector *connector, bool force)
  

+{

• struct i2c_client *stdp4028_i2c =

• 	ge_b850v3_lvds_ptr->stdp4028_i2c;
  

• s32 link_state;
• link_state = i2c_smbus_read_word_data(stdp4028_i2c,

• 			      STDP4028_DPTX_STS_REG);
  

• if (link_state == STDP4028_CON_STATE_CONNECTED)

• return connector_status_connected;
  

• if (link_state == 0)

• return connector_status_disconnected;
  

• return connector_status_unknown;

+}

+static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {

• .dpms = drm_atomic_helper_connector_dpms,
• .fill_modes = drm_helper_probe_single_connector_modes,
• .detect = ge_b850v3_lvds_detect,
• .destroy = drm_connector_cleanup,
• .reset = drm_atomic_helper_connector_reset,
• .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
• .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,

+};

+static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id) +{

• struct i2c_client *stdp4028_i2c

• 	= ge_b850v3_lvds_ptr->stdp4028_i2c;
  

• i2c_smbus_write_word_data(stdp4028_i2c,

• 		  STDP4028_DPTX_IRQ_STS_REG,
  

• 		  STDP4028_DPTX_IRQ_CLEAR);
  

• if (ge_b850v3_lvds_ptr->connector.dev)

• drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->connector.dev);
  

• return IRQ_HANDLED;

+}

+static int ge_b850v3_lvds_attach(struct drm_bridge *bridge) +{

• struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
• struct i2c_client *stdp4028_i2c

• 	= ge_b850v3_lvds_ptr->stdp4028_i2c;
  

• int ret;
• if (!bridge->encoder) {

• DRM_ERROR("Parent encoder object not found");
  

• return -ENODEV;
  

• }
• connector->polled = DRM_CONNECTOR_POLL_HPD;
• drm_connector_helper_add(connector,

• 		 &ge_b850v3_lvds_connector_helper_funcs);
  

• ret = drm_connector_init(bridge->dev, connector,

• 		 &ge_b850v3_lvds_connector_funcs,
  

• 		 DRM_MODE_CONNECTOR_DisplayPort);
  

• if (ret) {

• DRM_ERROR("Failed to initialize connector with drm\n");
  

• return ret;
  

• }
• ret = drm_mode_connector_attach_encoder(connector, bridge->encoder);
• if (ret)

• return ret;
  

• /* Configures the bridge to re-enable interrupts after each ack. */
• i2c_smbus_write_word_data(stdp4028_i2c,

• 		  STDP4028_IRQ_OUT_CONF_REG,
  

• 		  STDP4028_DPTX_DP_IRQ_EN);
  

• /* Enable interrupts */
• i2c_smbus_write_word_data(stdp4028_i2c,

• 		  STDP4028_DPTX_IRQ_EN_REG,
  

• 		  STDP4028_DPTX_IRQ_CONFIG);
  

• return 0;

+}

+static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {

• .attach = ge_b850v3_lvds_attach,

+};

+static int ge_b850v3_lvds_init(struct device *dev) +{

• mutex_lock(&ge_b850v3_lvds_dev_mutex);
• if (ge_b850v3_lvds_ptr)

• goto success;
  

• ge_b850v3_lvds_ptr = devm_kzalloc(dev,

• 			  sizeof(*ge_b850v3_lvds_ptr),
  

• 			  GFP_KERNEL);
  

• if (!ge_b850v3_lvds_ptr) {

• mutex_unlock(&ge_b850v3_lvds_dev_mutex);
  

• return -ENOMEM;
  

• }
• ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
• ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
• drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);

+success:

• mutex_unlock(&ge_b850v3_lvds_dev_mutex);
• return 0;

+}

+static void ge_b850v3_lvds_remove(void) +{

• mutex_lock(&ge_b850v3_lvds_dev_mutex);
• /*

• * This check is to avoid both the drivers
  

• * removing the bridge in their remove() function
  

• */
  

• if (!ge_b850v3_lvds_ptr)

• goto out;
  

• drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);
• kfree(ge_b850v3_lvds_ptr->edid);
• ge_b850v3_lvds_ptr = NULL;

+out:

• mutex_unlock(&ge_b850v3_lvds_dev_mutex);

+}

+static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c,

• 		       const struct i2c_device_id *id)
  

+{

• struct device *dev = &stdp4028_i2c->dev;
• ge_b850v3_lvds_init(dev);
• ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
• i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);
• /* Clear pending interrupts since power up. */
• i2c_smbus_write_word_data(stdp4028_i2c,

• 		  STDP4028_DPTX_IRQ_STS_REG,
  

• 		  STDP4028_DPTX_IRQ_CLEAR);
  

• if (!stdp4028_i2c->irq)

• return 0;
  

• return devm_request_threaded_irq(&stdp4028_i2c->dev,

• 	stdp4028_i2c->irq, NULL,
  

• 	ge_b850v3_lvds_irq_handler,
  

• 	IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
  

• 	"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
  

+}

+static int stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c) +{

• ge_b850v3_lvds_remove();
• return 0;

+}

+static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {

• {"stdp4028_ge_fw", 0},
• {},

+}; +MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);

+static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {

• { .compatible = "megachips,stdp4028-ge-b850v3-fw" },
• {},

+}; +MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);

+static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {

• .id_table = stdp4028_ge_b850v3_fw_i2c_table,
• .probe = stdp4028_ge_b850v3_fw_probe,
• .remove = stdp4028_ge_b850v3_fw_remove,
• .driver = {

• .name		= "stdp4028-ge-b850v3-fw",
  

• .of_match_table = stdp4028_ge_b850v3_fw_match,
  

• },

+}; +module_i2c_driver(stdp4028_ge_b850v3_fw_driver);

+static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c,

• 		       const struct i2c_device_id *id)
  

+{

• struct device *dev = &stdp2690_i2c->dev;
• ge_b850v3_lvds_init(dev);
• ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
• i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);
• return 0;

+}

+static int stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c) +{

• ge_b850v3_lvds_remove();
• return 0;

+}

+static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {

• {"stdp2690_ge_fw", 0},
• {},

+}; +MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);

+static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {

• { .compatible = "megachips,stdp2690-ge-b850v3-fw" },
• {},

+}; +MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);

+static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {

• .id_table = stdp2690_ge_b850v3_fw_i2c_table,
• .probe = stdp2690_ge_b850v3_fw_probe,
• .remove = stdp2690_ge_b850v3_fw_remove,
• .driver = {

• .name		= "stdp2690-ge-b850v3-fw",
  

• .of_match_table = stdp2690_ge_b850v3_fw_match,
  

• },

+}; +module_i2c_driver(stdp2690_ge_b850v3_fw_driver);

Didn't catch this in the last series, but there can only be one module_init call per module. This breaks compilation when the driver is built as a module.

Unfortunately yes. Got loads of errors when trying to compile as a module.

...

You could do something like:

static int __init stdpxxxx_ge_b850v3_init(void) { int ret;

ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver); if (ret) return ret;

return i2c_add_driver(&stdp2690_ge_b850v3_fw_driver); } module_init(stdpxxxx_ge_b850v3_init);

static void __exit stdpxxxx_ge_b850v3_exit(void) { i2c_del_driver(&stdp2690_ge_b850v3_fw_driver); i2c_del_driver(&stdp4028_ge_b850v3_fw_driver); } module_exit(stdpxxxx_ge_b850v3_exit);

Thank you! I was wondering if merging ge_b850v3_lvds_init() with stdpxxxx_ge_b850v3_init() and ge_b850v3_lvds_remove() with stdpxxxx_ge_b850v3_exit() make sense as it can probably eliminate the need for the mutex.

Doing anything apart from the driver registration/unregistration in the module_init/exit calls is frowned upon. Nothing specific to the device should ideally be added in them.

It would be nice to eventually get rid of the lvds_dev_mutex, but I think we can live with it for now.

Regards, Archit