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SubjectRe: [PATCH v10 1/4] drm/msm/dp: Add eDP support via aux_bus
From
On 25/04/2022 14:44, Sankeerth Billakanti wrote:
> This patch adds support for generic eDP sink through aux_bus. The eDP/DP
> controller driver should support aux transactions originating from the
> panel-edp driver and hence should be initialized and ready.
>
> The panel bridge supporting the panel should be ready before the bridge
> connector is initialized. The generic panel probe needs the controller
> resources to be enabled to support the aux transactions originating from
> the panel probe.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> Reviewed-by: Stephen Boyd <swboyd@chromium.org>

An additional side effect from this patch. Previously missing panel
would have caused the bind error. Now it is the dp_modeset_init error,
which translates to kms_hw_init returning -517. I kind ask to move the
next_bridge acquisition back to the dp_bind in one of the followup patches.

> ---
> Changes in v10:
> - modify the error handling condition
> - modify the kernel doc
>
> Changes in v9:
> - add comments for panel probe
> - modify the error handling checks
>
> Changes in v8:
> - handle corner cases
> - add comment for the bridge ops
>
> Changes in v7:
> - aux_bus is mandatory for eDP
> - connector type check modified to just check for eDP
>
> Changes in v6:
> - Remove initialization
> - Fix aux_bus node leak
> - Split the patches
>
> drivers/gpu/drm/msm/dp/dp_display.c | 72 ++++++++++++++++++++++++++++++++++---
> drivers/gpu/drm/msm/dp/dp_display.h | 1 +
> drivers/gpu/drm/msm/dp/dp_drm.c | 21 ++++++++---
> drivers/gpu/drm/msm/dp/dp_parser.c | 23 ++----------
> drivers/gpu/drm/msm/dp/dp_parser.h | 14 +++++++-
> 5 files changed, 101 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index d7a19d6..f772d84 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -10,6 +10,7 @@
> #include <linux/component.h>
> #include <linux/of_irq.h>
> #include <linux/delay.h>
> +#include <drm/dp/drm_dp_aux_bus.h>
>
> #include "msm_drv.h"
> #include "msm_kms.h"
> @@ -259,14 +260,12 @@ static int dp_display_bind(struct device *dev, struct device *master,
> dp->dp_display.drm_dev = drm;
> priv->dp[dp->id] = &dp->dp_display;
>
> - rc = dp->parser->parse(dp->parser, dp->dp_display.connector_type);
> + rc = dp->parser->parse(dp->parser);
> if (rc) {
> DRM_ERROR("device tree parsing failed\n");
> goto end;
> }
>
> - dp->dp_display.next_bridge = dp->parser->next_bridge;
> -
> dp->aux->drm_dev = drm;
> rc = dp_aux_register(dp->aux);
> if (rc) {
> @@ -1319,6 +1318,8 @@ static int dp_display_probe(struct platform_device *pdev)
> dp->pdev = pdev;
> dp->name = "drm_dp";
> dp->dp_display.connector_type = desc->connector_type;
> + dp->dp_display.is_edp =
> + (dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP);
>
> rc = dp_init_sub_modules(dp);
> if (rc) {
> @@ -1508,7 +1509,8 @@ void msm_dp_irq_postinstall(struct msm_dp *dp_display)
>
> dp_hpd_event_setup(dp);
>
> - dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
> + if (!dp_display->is_edp)
> + dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
> }
>
> void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
> @@ -1530,6 +1532,64 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
> }
> }
>
> +static int dp_display_get_next_bridge(struct msm_dp *dp)
> +{
> + int rc;
> + struct dp_display_private *dp_priv;
> + struct device_node *aux_bus;
> + struct device *dev;
> +
> + dp_priv = container_of(dp, struct dp_display_private, dp_display);
> + dev = &dp_priv->pdev->dev;
> + aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> +
> + if (aux_bus && dp->is_edp) {
> + dp_display_host_init(dp_priv);
> + dp_catalog_ctrl_hpd_config(dp_priv->catalog);
> + dp_display_host_phy_init(dp_priv);
> + enable_irq(dp_priv->irq);
> +
> + /*
> + * The code below assumes that the panel will finish probing
> + * by the time devm_of_dp_aux_populate_ep_devices() returns.
> + * This isn't a great assumption since it will fail if the
> + * panel driver is probed asynchronously but is the best we
> + * can do without a bigger driver reorganization.
> + */
> + rc = devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
> + of_node_put(aux_bus);
> + if (rc)
> + goto error;
> + } else if (dp->is_edp) {
> + DRM_ERROR("eDP aux_bus not found\n");
> + return -ENODEV;
> + }
> +
> + /*
> + * External bridges are mandatory for eDP interfaces: one has to
> + * provide at least an eDP panel (which gets wrapped into panel-bridge).
> + *
> + * For DisplayPort interfaces external bridges are optional, so
> + * silently ignore an error if one is not present (-ENODEV).
> + */
> + rc = dp_parser_find_next_bridge(dp_priv->parser);
> + if (!dp->is_edp && rc == -ENODEV)
> + return 0;
> +
> + if (!rc) {
> + dp->next_bridge = dp_priv->parser->next_bridge;
> + return 0;
> + }
> +
> +error:
> + if (dp->is_edp) {
> + disable_irq(dp_priv->irq);
> + dp_display_host_phy_exit(dp_priv);
> + dp_display_host_deinit(dp_priv);
> + }
> + return rc;
> +}
> +
> int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
> struct drm_encoder *encoder)
> {
> @@ -1553,6 +1613,10 @@ int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
>
> dp_display->encoder = encoder;
>
> + ret = dp_display_get_next_bridge(dp_display);
> + if (ret)
> + return ret;
> +
> dp_display->bridge = dp_bridge_init(dp_display, dev, encoder);
> if (IS_ERR(dp_display->bridge)) {
> ret = PTR_ERR(dp_display->bridge);
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 49a1d89..1377cc3 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -21,6 +21,7 @@ struct msm_dp {
> bool audio_enabled;
> bool power_on;
> unsigned int connector_type;
> + bool is_edp;
>
> hdmi_codec_plugged_cb plugged_cb;
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> index 7ce1aca..8a75c55 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> @@ -114,10 +114,23 @@ struct drm_bridge *dp_bridge_init(struct msm_dp *dp_display, struct drm_device *
> bridge->funcs = &dp_bridge_ops;
> bridge->type = dp_display->connector_type;
>
> - bridge->ops =
> - DRM_BRIDGE_OP_DETECT |
> - DRM_BRIDGE_OP_HPD |
> - DRM_BRIDGE_OP_MODES;
> + /*
> + * Many ops only make sense for DP. Why?
> + * - Detect/HPD are used by DRM to know if a display is _physically_
> + * there, not whether the display is powered on / finished initting.
> + * On eDP we assume the display is always there because you can't
> + * know until power is applied. If we don't implement the ops DRM will
> + * assume our display is always there.
> + * - Currently eDP mode reading is driven by the panel driver. This
> + * allows the panel driver to properly power itself on to read the
> + * modes.
> + */
> + if (!dp_display->is_edp) {
> + bridge->ops =
> + DRM_BRIDGE_OP_DETECT |
> + DRM_BRIDGE_OP_HPD |
> + DRM_BRIDGE_OP_MODES;
> + }
>
> rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> if (rc) {
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
> index 1056b8d..4bdbf91 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
> @@ -265,7 +265,7 @@ static int dp_parser_clock(struct dp_parser *parser)
> return 0;
> }
>
> -static int dp_parser_find_next_bridge(struct dp_parser *parser)
> +int dp_parser_find_next_bridge(struct dp_parser *parser)
> {
> struct device *dev = &parser->pdev->dev;
> struct drm_bridge *bridge;
> @@ -279,7 +279,7 @@ static int dp_parser_find_next_bridge(struct dp_parser *parser)
> return 0;
> }
>
> -static int dp_parser_parse(struct dp_parser *parser, int connector_type)
> +static int dp_parser_parse(struct dp_parser *parser)
> {
> int rc = 0;
>
> @@ -300,25 +300,6 @@ static int dp_parser_parse(struct dp_parser *parser, int connector_type)
> if (rc)
> return rc;
>
> - /*
> - * External bridges are mandatory for eDP interfaces: one has to
> - * provide at least an eDP panel (which gets wrapped into panel-bridge).
> - *
> - * For DisplayPort interfaces external bridges are optional, so
> - * silently ignore an error if one is not present (-ENODEV).
> - */
> - rc = dp_parser_find_next_bridge(parser);
> - if (rc == -ENODEV) {
> - if (connector_type == DRM_MODE_CONNECTOR_eDP) {
> - DRM_ERROR("eDP: next bridge is not present\n");
> - return rc;
> - }
> - } else if (rc) {
> - if (rc != -EPROBE_DEFER)
> - DRM_ERROR("DP: error parsing next bridge: %d\n", rc);
> - return rc;
> - }
> -
> /* Map the corresponding regulator information according to
> * version. Currently, since we only have one supported platform,
> * mapping the regulator directly.
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
> index d371bae..3a4d797 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
> @@ -125,7 +125,7 @@ struct dp_parser {
> u32 max_dp_lanes;
> struct drm_bridge *next_bridge;
>
> - int (*parse)(struct dp_parser *parser, int connector_type);
> + int (*parse)(struct dp_parser *parser);
> };
>
> /**
> @@ -141,4 +141,16 @@ struct dp_parser {
> */
> struct dp_parser *dp_parser_get(struct platform_device *pdev);
>
> +/**
> + * dp_parser_find_next_bridge() - find an additional bridge to DP
> + *
> + * @parser: dp_parser data from client
> + *
> + * This function is used to find any additional bridge attached to
> + * the DP controller. The eDP interface requires a panel bridge.
> + *
> + * Return: 0 if able to get the bridge, otherwise negative errno for failure.
> + */
> +int dp_parser_find_next_bridge(struct dp_parser *parser);
> +
> #endif


--
With best wishes
Dmitry

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