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Thu, 16 Oct 2025 10:56:48 -0700 (PDT) From: =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= To: louis.chauvet@bootlin.com Cc: hamohammed.sa@gmail.com, simona@ffwll.ch, melissa.srw@gmail.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, sebastian.wick@redhat.com, xaver.hugl@kde.org, victoria@system76.com, a.hindborg@kernel.org, leitao@debian.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Mark Yacoub , Harry Wentland , Luca Ceresoli , =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= Subject: [PATCH v7 06/16] drm/vkms: Allow to configure CRTC writeback support via configfs Date: Thu, 16 Oct 2025 19:56:08 +0200 Message-ID: <20251016175618.10051-7-jose.exposito89@gmail.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251016175618.10051-1-jose.exposito89@gmail.com> References: <20251016175618.10051-1-jose.exposito89@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Louis Chauvet When a CRTC is created, add a `writeback` file to allow to enable or disable writeback connector support Tested-by: Mark Yacoub Reviewed-by: Louis Chauvet Reviewed-by: Harry Wentland Reviewed-by: Luca Ceresoli Signed-off-by: Louis Chauvet Co-developed-by: Jos=C3=A9 Exp=C3=B3sito Signed-off-by: Jos=C3=A9 Exp=C3=B3sito --- Documentation/gpu/vkms.rst | 4 +++ drivers/gpu/drm/vkms/vkms_configfs.c | 42 ++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst index 7396447b5e58..9f76918bb1d1 100644 --- a/Documentation/gpu/vkms.rst +++ b/Documentation/gpu/vkms.rst @@ -94,6 +94,10 @@ Continue by creating one or more CRTCs:: =20 sudo mkdir /config/vkms/my-vkms/crtcs/crtc0 =20 +CRTCs have 1 configurable attribute: + +- writeback: Enable or disable writeback connector support by writing 1 or= 0 + Once you are done configuring the VKMS instance, enable it:: =20 echo "1" | sudo tee /config/vkms/my-vkms/enabled diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vk= ms_configfs.c index 62a82366791d..e9f445043268 100644 --- a/drivers/gpu/drm/vkms/vkms_configfs.c +++ b/drivers/gpu/drm/vkms/vkms_configfs.c @@ -74,6 +74,47 @@ struct vkms_configfs_crtc { #define crtc_item_to_vkms_configfs_crtc(item) \ container_of(to_config_group((item)), struct vkms_configfs_crtc, group) =20 +static ssize_t crtc_writeback_show(struct config_item *item, char *page) +{ + struct vkms_configfs_crtc *crtc; + bool writeback; + + crtc =3D crtc_item_to_vkms_configfs_crtc(item); + + scoped_guard(mutex, &crtc->dev->lock) + writeback =3D vkms_config_crtc_get_writeback(crtc->config); + + return sprintf(page, "%d\n", writeback); +} + +static ssize_t crtc_writeback_store(struct config_item *item, const char *= page, + size_t count) +{ + struct vkms_configfs_crtc *crtc; + bool writeback; + + crtc =3D crtc_item_to_vkms_configfs_crtc(item); + + if (kstrtobool(page, &writeback)) + return -EINVAL; + + scoped_guard(mutex, &crtc->dev->lock) { + if (crtc->dev->enabled) + return -EBUSY; + + vkms_config_crtc_set_writeback(crtc->config, writeback); + } + + return (ssize_t)count; +} + +CONFIGFS_ATTR(crtc_, writeback); + +static struct configfs_attribute *crtc_item_attrs[] =3D { + &crtc_attr_writeback, + NULL, +}; + static void crtc_release(struct config_item *item) { struct vkms_configfs_crtc *crtc; @@ -93,6 +134,7 @@ static struct configfs_item_operations crtc_item_operati= ons =3D { }; =20 static const struct config_item_type crtc_item_type =3D { + .ct_attrs =3D crtc_item_attrs, .ct_item_ops =3D &crtc_item_operations, .ct_owner =3D THIS_MODULE, }; --=20 2.51.0