linux-kernel - [PATCH RFC v2 15/16] drm/vkms: Introduce configfs for connector EDID

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Message-Id: <20241122-google-config-fs-v2-15-4b7e6f183320@bootlin.com>
Date: Fri, 22 Nov 2024 18:38:41 +0100
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>, 
 Melissa Wen <melissa.srw@...il.com>, 
 Maíra Canal <mairacanal@...eup.net>, 
 Haneen Mohammed <hamohammed.sa@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Simona Vetter <simona.vetter@...ll.ch>
Cc: jose.exposito89@...il.com, dri-devel@...ts.freedesktop.org, 
 arthurgrillo@...eup.net, linux-kernel@...r.kernel.org, 
 jeremie.dautheribes@...tlin.com, miquel.raynal@...tlin.com, 
 thomas.petazzoni@...tlin.com, seanpaul@...gle.com, nicolejadeyee@...gle.com, 
 Louis Chauvet <louis.chauvet@...tlin.com>
Subject: [PATCH RFC v2 15/16] drm/vkms: Introduce configfs for connector
 EDID

Due to limitation of ConfigFS, the max len of EDID is PAGE_SIZE (4kB on
x86), it should be sufficient for many tests. One possible evolution is
using a ConfigFS blob to allow bigger EDID.

The EDID can be changed at any time. As for physical display, you need
to trigger an HPD event to refresh the modes.

Signed-off-by: Louis Chauvet <louis.chauvet@...tlin.com>
---
 drivers/gpu/drm/vkms/vkms_configfs.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 45738707f1f6c11b561e695fe0aef245d946b418..55bd0b9a31d35eca49c67a2fe2d58e3ea84367a4 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -1024,6 +1024,37 @@ static ssize_t connector_status_store(struct config_item *item,
 	return count;
 }
 
+static ssize_t connector_edid_show(struct config_item *item, char *page)
+{
+	struct vkms_config_connector *connector;
+	struct vkms_configfs_device *vkms_configfs = connector_child_item_to_vkms_configfs_device(item);
+
+	scoped_guard(mutex, &vkms_configfs->lock)
+	{
+		connector = connector_item_to_vkms_configfs_connector(item)->vkms_config_connector;
+		memcpy(page, &connector->edid_blob, connector->edid_blob_len);
+		return connector->edid_blob_len;
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t connector_edid_store(struct config_item *item,
+				    const char *page, size_t count)
+{
+	struct vkms_configfs_device *vkms_configfs = connector_child_item_to_vkms_configfs_device(item);
+
+	scoped_guard(mutex, &vkms_configfs->lock)
+	{
+		struct vkms_config_connector *connector =
+			connector_item_to_vkms_configfs_connector(item)->vkms_config_connector;
+		memcpy(&connector->edid_blob, page, count);
+		connector->edid_blob_len = count;
+	}
+
+	return count;
+}
+
 static ssize_t connector_id_show(struct config_item *item, char *page)
 {
 	struct vkms_configfs_device *vkms_configfs =
@@ -1043,12 +1074,14 @@ static ssize_t connector_id_show(struct config_item *item, char *page)
 
 CONFIGFS_ATTR(connector_, type);
 CONFIGFS_ATTR(connector_, status);
+CONFIGFS_ATTR(connector_, edid);
 CONFIGFS_ATTR_RO(connector_, id);
 
 static struct configfs_attribute *connector_attrs[] = {
 	&connector_attr_type,
 	&connector_attr_status,
 	&connector_attr_id,
+	&connector_attr_edid,
 	NULL,
 };
 

-- 
2.47.0