Le 19/08/24 - 17:07, José Expósito a écrit :
> Hi Louis,
>
> Thanks for this patch, adding some minor review comments:
>
> > Add documentation around vkms_output and its initialization.
> >
> > Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/vkms/vkms_drv.h | 81 ++++++++++++++++++++++++++++++++------
> > drivers/gpu/drm/vkms/vkms_output.c | 12 +++++-
> > 2 files changed, 80 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> > index 3028678e4f9b..8f6c9e67e671 100644
> > --- a/drivers/gpu/drm/vkms/vkms_drv.h
> > +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> > @@ -147,29 +147,51 @@ struct vkms_color_lut {
> > };
> >
> > /**
> > - * vkms_crtc_state - Driver specific CRTC state
> > + * struct vkms_crtc_state - Driver specific CRTC state
>
> Not in this line, but around line 55, the documentation for vkms_plane_state
> is missing the "struct" keyword:
This is fixed by [1], but I can move this patch here.
[1]: https://lore.kernel.org/all/20240802-yuv-v9-3-08a706669e16@xxxxxxxxxxx/
> - * vkms_plane_state - Driver specific plane state
> + * struct vkms_plane_state - Driver specific plane state
>
> I'd be nice to add it since we are improving the documentation.
>
> > + *
> > * @base: base CRTC state
> > * @composer_work: work struct to compose and add CRC entries
> > - * @n_frame_start: start frame number for computed CRC
> > - * @n_frame_end: end frame number for computed CRC
> > + *
> > + * @num_active_planes: Number of active planes
> > + * @active_planes: List containing all the active planes (counted by
> > + * @num_active_planes). They should be stored in z-order.
> > + * @active_writeback: Current active writeback job
> > + * @gamma_lut: Look up table for gamma used in this CRTC
> > + * @crc_pending: Protected by @vkms_output.composer_lock.
> > + * @wb_pending: Protected by @vkms_output.composer_lock.
> > + * @frame_start: Protected by @vkms_output.composer_lock.
> > + * @frame_end: Protected by @vkms_output.composer_lock.
> > */
> > struct vkms_crtc_state {
> > struct drm_crtc_state base;
> > struct work_struct composer_work;
> >
> > int num_active_planes;
> > - /* stack of active planes for crc computation, should be in z order */
> > struct vkms_plane_state **active_planes;
> > struct vkms_writeback_job *active_writeback;
> > struct vkms_color_lut gamma_lut;
> >
> > - /* below four are protected by vkms_output.composer_lock */
> > bool crc_pending;
> > bool wb_pending;
> > u64 frame_start;
> > u64 frame_end;
> > };
> >
> > +/**
> > + * struct vkms_output - Internal representation of all output components in vkms
>
> I think that VKMS is usually spelled in capital letters in other places.
>
> > + *
> > + * @crtc: Base crtc in drm
> > + * @encoder: DRM encoder used for this output
> > + * @connector: DRM connector used for this output
> > + * @wb_connecter: DRM writeback connector used for this output
> > + * @vblank_hrtimer:
> > + * @period_ns:
>
> My suggestion when reviewing a previous version of this patch in your
> GitHub fork was:
>
> @vblank_hrtimer: Timer used to simulate vblank events
> @period_ns: vblank period, in nanoseconds
>
> > + * @composer_workq: Ordered workqueue for composer_work
> > + * @lock: Lock used to project concurrent acces to the composer
> > + * @composer_enabled: Protected by @lock.
> > + * @composer_state:
>
> I think that @composer_state is "Protected by @lock" as well.
>
> > + * @composer_lock: Lock used internally to protect @composer_state members
> > + */
> > struct vkms_output {
> > struct drm_crtc crtc;
> > struct drm_encoder encoder;
> > @@ -177,28 +199,38 @@ struct vkms_output {
> > struct drm_writeback_connector wb_connector;
> > struct hrtimer vblank_hrtimer;
> > ktime_t period_ns;
> > - /* ordered wq for composer_work */
> > struct workqueue_struct *composer_workq;
> > - /* protects concurrent access to composer */
> > spinlock_t lock;
> >
> > - /* protected by @lock */
> > bool composer_enabled;
> > struct vkms_crtc_state *composer_state;
> >
> > spinlock_t composer_lock;
> > };
> >
> > -struct vkms_device;
> > -
> > +/**
> > + * struct vkms_config - General configuration for VKMS driver
> > + *
> > + * @writeback: If true, a writeback buffer can be attached to the CRTC
> > + * @cursor: If true, a cursor plane is created in the VKMS device
> > + * @overlay: If true, NUM_OVERLAY_PLANES will be created for the VKMS device
> > + * @dev: Used to store the current vkms device. Only set when the device is instancied.
>
> s/vkms/VKMS and s/instancied/instantiated
>
> > + */
> > struct vkms_config {
> > bool writeback;
> > bool cursor;
> > bool overlay;
> > - /* only set when instantiated */
> > struct vkms_device *dev;
> > };
> >
> > +/**
> > + * struct vkms_device - Description of a vkms device
>
> s/vkms/VKMS
>
> > + *
> > + * @drm - Base device in drm
> > + * @platform - Associated platform device
> > + * @output - Configuration and sub-components of the vkms device
>
> s/vkms/VKMS
>
> > + * @config: Configuration used in this vkms device
>
> s/vkms/VKMS
>
> > + */
> > struct vkms_device {
> > struct drm_device drm;
> > struct platform_device *platform;
> > @@ -206,6 +238,10 @@ struct vkms_device {
> > const struct vkms_config *config;
> > };
> >
> > +/*
> > + * The following helpers are used to convert a member of a struct into its parent.
> > + */
> > +
> > #define drm_crtc_to_vkms_output(target) \
> > container_of(target, struct vkms_output, crtc)
> >
> > @@ -218,12 +254,33 @@ struct vkms_device {
> > #define to_vkms_plane_state(target)\
> > container_of(target, struct vkms_plane_state, base.base)
> >
> > -/* CRTC */
> > +/**
> > + * vkms_crtc_init() - Initialize a crtc for vkms
>
> s/vkms/VKMS
>
> > + * @dev: drm_device associated with the vkms buffer
>
> s/vkms/VKMS
>
> > + * @crtc: uninitialized crtc device
> > + * @primary: primary plane to attach to the crtc
> > + * @cursor plane to attach to the crtc
> > + */
> > int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
> > struct drm_plane *primary, struct drm_plane *cursor);
> > +/**
> > + * vkms_output_init() - Initialize all sub-components needed for a vkms device.
>
> s/vkms/VKMS
>
> > + *
> > + * @vkmsdev: vkms device to initialize
>
> s/vkms/VKMS
>
> > + * @possible_crtc_index: Crtc which can be attached to the planes. The caller must ensure that
> > + * possible_crtc_index is positive and less or equals to 31.
>
> Missing "@". Also, since the second patch of this series won't be applied,
> remember to rename the documentation to "@index".
> > + */
> >
> > int vkms_output_init(struct vkms_device *vkmsdev, int possible_crtc_index);
> >
> > +/**
> > + * vkms_plane_init() - Initialize a plane
> > + *
> > + * @vkmsdev: vkms device containing the plane
>
> s/vkms/VKMS
>
> > + * @type: type of plane to initialize
> > + * @possible_crtc_index: Crtc which can be attached to the plane. The caller must ensure that
> > + * possible_crtc_index is positive and less or equals to 31.
> > + */
> > struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
> > enum drm_plane_type type, int possible_crtc_index);
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
> > index d42ca7d10389..36db2c8923cb 100644
> > --- a/drivers/gpu/drm/vkms/vkms_output.c
> > +++ b/drivers/gpu/drm/vkms/vkms_output.c
> > @@ -21,6 +21,7 @@ static int vkms_conn_get_modes(struct drm_connector *connector)
> > {
> > int count;
> >
> > + /* Use the default modes list from drm */
> > count = drm_add_modes_noedid(connector, XRES_MAX, YRES_MAX);
> > drm_set_preferred_mode(connector, XRES_DEF, YRES_DEF);
> >
> > @@ -58,8 +59,13 @@ int vkms_output_init(struct vkms_device *vkmsdev, int possible_crtc_index)
> > int writeback;
> > unsigned int n;
> >
> > + /*
> > + * Initialize used plane. One primary plane is required to perform the composition.
> > + *
> > + * The overlay and cursor planes are not mandatory, but can be used to perform complex
> > + * composition.
> > + */
> > primary = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_PRIMARY, possible_crtc_index);
> > -
> > if (IS_ERR(primary))
> > return PTR_ERR(primary);
> >
> > @@ -96,6 +102,10 @@ int vkms_output_init(struct vkms_device *vkmsdev, int possible_crtc_index)
> > DRM_ERROR("Failed to init encoder\n");
> > goto err_encoder;
> > }
> > + /*
> > + * This is an hardcoded value to select crtc for the encoder.
>
> s/an/a
>
> > + * 1 here designate the first registered CRTC, the one allocated in [1]
> > + */
>
> I think that replacing "= 1;" with "= BIT(0);" might help to understand
> that possible_crtcs is a bitmask and also that CRTC 0 is used by default.
> We might even be able to drop the comment... Even though this will change
> with our configfs changes quite a lot.
This comment was mainly for me to understand why there is this =1.
I will change it to =BIT(0) for clarity, but keep the comment as it is not
obvious why this value is hardcoded.
> > encoder->possible_crtcs = 1;
> >
> > ret = drm_connector_attach_encoder(connector, encoder);
