Re: [PATCH 10/60] drm/bridge: Add bridge driver for display connectors

Hi Laurent.

Two small details, see below.

Sam

On Sun, Jul 07, 2019 at 09:18:47PM +0300, Laurent Pinchart wrote:

Display connectors are modelled in DT as a device node, but have so far been handled manually in several bridge drivers. This resulted in duplicate code in several bridge drivers, with slightly different (and thus confusing) logics.

In order to fix this, implement a bridge driver for display connectors. The driver centralises logic for the DVI, HDMI, VGAn composite and S-video connectors and exposes corresponding bridge operations.

This driver in itself doesn't solve the issue completely, changes in bridge and display controller drivers are needed to make use of the new connector driver.

Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com

drivers/gpu/drm/bridge/Kconfig | 11 + drivers/gpu/drm/bridge/Makefile | 1 + drivers/gpu/drm/bridge/display-connector.c | 327 +++++++++++++++++++++ 3 files changed, 339 insertions(+) create mode 100644 drivers/gpu/drm/bridge/display-connector.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig index a78392e2dbb9..295a62f65ef9 100644 --- a/drivers/gpu/drm/bridge/Kconfig +++ b/drivers/gpu/drm/bridge/Kconfig @@ -37,6 +37,17 @@ config DRM_CDNS_DSI Support Cadence DPI to DSI bridge. This is an internal bridge and is meant to be directly embedded in a SoC.

+config DRM_DISPLAY_CONNECTOR

• tristate "Display connector support"
• depends on OF
• help

•  Driver for display connectors with support for DDC and hot-plug
  

•  detection. Most display controller handle display connectors
  

•  internally and don't need this driver, but the DRM subsystem is
  

•  moving towards separating connector handling from display controllers
  

•  on ARM-based platforms. Saying Y here when this driver is not needed
  

•  will not cause any issue.
  

config DRM_LVDS_ENCODER tristate "Transparent parallel to LVDS encoder support" depends on OF diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile index 6ff7f2adbb0e..e5987b3aaf62 100644 --- a/drivers/gpu/drm/bridge/Makefile +++ b/drivers/gpu/drm/bridge/Makefile @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o +obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o obj-$(CONFIG_DRM_LVDS_ENCODER) += lvds-encoder.o obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o diff --git a/drivers/gpu/drm/bridge/display-connector.c b/drivers/gpu/drm/bridge/display-connector.c new file mode 100644 index 000000000000..2e1e7ee89275 --- /dev/null +++ b/drivers/gpu/drm/bridge/display-connector.c @@ -0,0 +1,327 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (C) 2019 Laurent Pinchart laurent.pinchart@ideasonboard.com
• */

...

+static void display_connector_hpd_enable(struct drm_bridge *bridge) +{ +}

+static void display_connector_hpd_disable(struct drm_bridge *bridge) +{ +}

It seems wrong that a new driver needs empty implementation of hpd_enable() and hpd_disable(). I noticed the same in a later patch too.

Can we do without these empty functions?

+static const struct drm_bridge_funcs display_connector_bridge_funcs = {

• .attach = display_connector_attach,
• .detect = display_connector_detect,
• .get_edid = display_connector_get_edid,
• .hpd_enable = display_connector_hpd_enable,
• .hpd_disable = display_connector_hpd_disable,

+};

• struct display_connector *conn = arg;
• struct drm_bridge *bridge = &conn->bridge;
• drm_bridge_hpd_notify(bridge, display_connector_detect(bridge));
• return IRQ_HANDLED;

+}

+static const char *display_connector_type_name(struct display_connector *conn) +{

• switch (conn->bridge.type) {
• case DRM_MODE_CONNECTOR_Composite:

• return "Composite";
  

• case DRM_MODE_CONNECTOR_DVIA:

• return "DVI-A";
  

• case DRM_MODE_CONNECTOR_DVID:

• return "DVI-D";
  

• case DRM_MODE_CONNECTOR_DVII:

• return "DVI-I";
  

• case DRM_MODE_CONNECTOR_HDMIA:

• return "HDMI-A";
  

• case DRM_MODE_CONNECTOR_HDMIB:

• return "HDMI-B";
  

• case DRM_MODE_CONNECTOR_SVIDEO:

• return "S-Video";
  

• case DRM_MODE_CONNECTOR_VGA:

• return "VGA";
  

• default:

• return "unknown";
  

• }

+}

We already have the relation DRM_MODE_CONNECTOR <=> name in drm_connector - see drm_connector_enum_list.

Add a small function in drm_connector.c get the name, so we do not hardcode the name twice?

Sam