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Date: Sat, 7 May 2022 00:05:01 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>,
Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org
Cc: robdclark@...il.com, seanpaul@...omium.org, swboyd@...omium.org,
quic_kalyant@...cinc.com, dianders@...omium.org,
quic_khsieh@...cinc.com, bjorn.andersson@...aro.org,
sean@...rly.run, airlied@...ux.ie, daniel@...ll.ch,
quic_vproddut@...cinc.com, quic_aravindh@...cinc.com,
steev@...i.org
Subject: Re: [PATCH v10 1/4] drm/msm/dp: Add eDP support via aux_bus
On 07/05/2022 00:03, Abhinav Kumar wrote:
>
>
> On 5/6/2022 1:49 PM, Dmitry Baryshkov wrote:
>> 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@...cinc.com>
>>> Reviewed-by: Douglas Anderson <dianders@...omium.org>
>>> Reviewed-by: Stephen Boyd <swboyd@...omium.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.
>>
>
> This is true. But the end result would be same isnt it?
>
> When dp_display_bind() failed earlier, it would cause master bind
> failure too due to component model.
>
> Even now, it causes the same result?
Yes, it helped us to uncover several error. But I'd still prefer to have
EPROBE_DEFER being returned earlier rather than later.
>
>>> ---
>>> 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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