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Message-ID: <c43ba749-5748-4646-ab35-0ab8c0e1fa78@huawei.com>
Date: Fri, 1 Aug 2025 17:24:39 +0800
From: Yongbang Shi <shiyongbang@...wei.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
CC: <xinliang.liu@...aro.org>, <tiantao6@...ilicon.com>,
<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
<tzimmermann@...e.de>, <airlied@...il.com>, <daniel@...ll.ch>,
<kong.kongxinwei@...ilicon.com>, <liangjian010@...wei.com>,
<chenjianmin@...wei.com>, <fengsheng5@...wei.com>, <libaihan@...wei.com>,
<shenjian15@...wei.com>, <shaojijie@...wei.com>,
<jani.nikula@...ux.intel.com>, <dri-devel@...ts.freedesktop.org>,
<linux-kernel@...r.kernel.org>, <shiyongbang@...wei.com>
Subject: Re: [PATCH v3 drm-dp 08/11] drm/hisilicon/hibmc: fix no showing when
no connectors connected
> On Fri, Jul 18, 2025 at 02:51:22PM +0800, Yongbang Shi wrote:
>> From: Baihan Li <libaihan@...wei.com>
>>
>> Our chip support KVM over IP feature, so hibmc diiver need to support
> I assume that KVM-over-IP doesnt provide EDID reads. This needs to be
> stated in the commit message.
Okay!
>> displaying without any connectors plugged in. If no connectors connected,
>> set the vdac connector status to 'connected' to handle BMC KVM. Use
>> is_connected to check all physical outputs.
>> For get_modes: using BMC modes for connector if no display is attached to
>> phys VGA cable, otherwise use EDID modes by drm_connector_helper_get_modes.
>>
>> Fixes: 4c962bc929f1 ("drm/hisilicon/hibmc: Add vga connector detect functions")
>> Signed-off-by: Baihan Li <libaihan@...wei.com>
>> Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
>> ---
>> ChangeLog:
>> v2 -> v3:
>> - fix hibmc_connector_get_modes() and hibmc_vdac_detect() to realize BMC KVM, suggested by Dmitry Baryshkov.
>> ---
>> .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 5 +-
>> .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h | 4 ++
>> .../gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c | 55 +++++++++++++------
>> 3 files changed, 45 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> index 99b30a6c7e06..262ebe6138f0 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> @@ -58,9 +58,12 @@ static int hibmc_dp_detect(struct drm_connector *connector,
>> {
>> struct hibmc_drm_private *priv = to_hibmc_drm_private(connector->dev);
>>
>> - if (!hibmc_dp_detect_link(&priv->dp))
>> + if (!hibmc_dp_detect_link(&priv->dp)) {
>> + priv->is_connected |= BIT(0);
> Magic value BIT(0)
>
>> return connector_status_connected;
>> + }
>>
>> + priv->is_connected &= ~BIT(0);
>> return connector_status_disconnected;
>> }
>>
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>> index ca8502e2760c..d68588ecec9b 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>> @@ -31,6 +31,7 @@ struct hibmc_vdac {
>> struct drm_connector connector;
>> struct i2c_adapter adapter;
>> struct i2c_algo_bit_data bit_data;
>> + int phys_status;
>> };
>>
>> struct hibmc_drm_private {
>> @@ -43,6 +44,9 @@ struct hibmc_drm_private {
>> struct drm_crtc crtc;
>> struct hibmc_vdac vdac;
>> struct hibmc_dp dp;
>> +
>> + /* VGA and DP phys connect status, BIT(0) is DP, BIT(1) is VGA */
> #define those.
>
>> + int is_connected;
> And you need a lock around this one, otherwise you might get a race
> between DP's and VGA's code setting and clearing bits here.
Okay, thanks for your advice!
I will modify all of the above issues.
>> };
>>
>> static inline struct hibmc_vdac *to_hibmc_vdac(struct drm_connector *connector)
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
>> index 841e81f47b68..3cdf640d1785 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
>> @@ -25,27 +25,18 @@
>> static int hibmc_connector_get_modes(struct drm_connector *connector)
>> {
>> struct hibmc_vdac *vdac = to_hibmc_vdac(connector);
>> - const struct drm_edid *drm_edid;
>> int count;
>>
>> - drm_edid = drm_edid_read_ddc(connector, &vdac->adapter);
>> -
>> - drm_edid_connector_update(connector, drm_edid);
>> -
>> - if (drm_edid) {
>> - count = drm_edid_connector_add_modes(connector);
>> - if (count)
>> - goto out;
>> + if (vdac->phys_status == connector_status_connected) {
>> + count = drm_connector_helper_get_modes(connector);
>> + } else {
>> + drm_edid_connector_update(connector, NULL);
>> + count = drm_add_modes_noedid(connector,
>> + connector->dev->mode_config.max_width,
>> + connector->dev->mode_config.max_height);
>> + drm_set_preferred_mode(connector, 1024, 768); // 1024x768
>> }
>>
>> - count = drm_add_modes_noedid(connector,
>> - connector->dev->mode_config.max_width,
>> - connector->dev->mode_config.max_height);
>> - drm_set_preferred_mode(connector, 1024, 768);
>> -
>> -out:
>> - drm_edid_free(drm_edid);
>> -
>> return count;
>> }
>>
>> @@ -57,10 +48,38 @@ static void hibmc_connector_destroy(struct drm_connector *connector)
>> drm_connector_cleanup(connector);
>> }
>>
>> +static int hibmc_vdac_detect(struct drm_connector *connector,
>> + struct drm_modeset_acquire_ctx *ctx,
>> + bool force)
>> +{
>> + struct hibmc_drm_private *priv = to_hibmc_drm_private(connector->dev);
>> + struct hibmc_vdac *vdac = to_hibmc_vdac(connector);
>> + enum drm_connector_status status;
>> +
>> + status = drm_connector_helper_detect_from_ddc(connector, ctx, force);
>> +
>> + vdac->phys_status = status;
>> +
>> + if (status == connector_status_connected) {
>> + priv->is_connected |= BIT(1);
>> + return connector_status_connected;
>> + }
>> +
>> + priv->is_connected &= ~BIT(1);
>> +
>> + /* if all connectors are disconnected,
>> + * return connected to support BMC KVM display.
>> + */
>> + if (!priv->is_connected)
>> + return connector_status_connected;
>> +
>> + return connector_status_disconnected;
>> +}
>> +
>> static const struct drm_connector_helper_funcs
>> hibmc_connector_helper_funcs = {
>> .get_modes = hibmc_connector_get_modes,
>> - .detect_ctx = drm_connector_helper_detect_from_ddc,
>> + .detect_ctx = hibmc_vdac_detect,
>> };
>>
>> static const struct drm_connector_funcs hibmc_connector_funcs = {
>> --
>> 2.33.0
>>
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