On 10/22, Daniel Vetter wrote:
> On Mon, Oct 22, 2018 at 09:27:18AM -0300, Rodrigo Siqueira wrote:
> > Hi,
> >
> > I started to work for add the writeback feature into the VKMS, and this
> > RFC represents my first draft. As a result, I have some questions which
> > I list below.
> >
> > 1. In this patch, I replaced the virtual connector by the writeback
> > connector. Is it a good idea? Or should I keep both connectors? If I
> > keep both connectors, should I add a module parameter to enable the
> > writeback?
>
> Yeah separate connector is imo better, with module config knob. Eventually
> we can move that into configfs or similar.
>
> > 2. When I added the writeback connector (in
> > drm_writeback_connector_init()), I noticed that I had to indicate the
> > struct drm_encoder_helper_funcs. However, I think that VKMS does not
> > need anything sophisticated related to encoders at the writeback
> > perspective. Am I right? Or did I missed something?
>
> Yeah, you don't need anything fancy in the drm_encoder. I think you could
> reuse the same dummy drm_encoder as we use for the normal connector.
>
> > 3. I just discovered that the writeback connectors are not exposed as a
> > connector for the userspace, as a result, IGT tests do not work and
> > Wayland is unable to run as well. Simon Ser and Daniel Stone, explained
> > to me that I have to update the compositor (in my case Weston) to set
> > DRM_CLIENT_CAP_WRITEBACK_CONNECTORS via drmSetClientCap(). Since I do
> > not have experience with userspace, anyone can point me out another
> > aspect that I have to take a look to make the writeback work in the user
> > space? Also, Is it possible to update the IGT test or do I need to
> > create a new set of tests?
>
> Yeah, writeback connector doesn't work like a normal connector, so it's
> hidden by default. There should be special writeback connector tests in
> igt though, but I guess those haven't been merged yet. Ask Liviu and Brian
> from arm where they're stuck. Without those it's going to be rather hard
> to make this work correctly.
Hi, thanks for the feedbacks
I will improve the code based on your comments, and for the testing
mechanism, I want to try to make rootston run on top of VKMS.
Best Regards
> Cheers, Daniel
>
> >
> > Thanks!
> >
> > Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/vkms/vkms_crc.c | 9 ++-
> > drivers/gpu/drm/vkms/vkms_crtc.c | 2 +
> > drivers/gpu/drm/vkms/vkms_drv.h | 3 +-
> > drivers/gpu/drm/vkms/vkms_output.c | 107 +++++++++++++++++++++--------
> > 4 files changed, 89 insertions(+), 32 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c
> > index 9d9e8146db90..5d9ac45e00f2 100644
> > --- a/drivers/gpu/drm/vkms/vkms_crc.c
> > +++ b/drivers/gpu/drm/vkms/vkms_crc.c
> > @@ -109,7 +109,8 @@ static void compose_cursor(struct vkms_crc_data *cursor_crc,
> > }
> >
> > static uint32_t _vkms_get_crc(struct vkms_crc_data *primary_crc,
> > - struct vkms_crc_data *cursor_crc)
> > + struct vkms_crc_data *cursor_crc,
> > + struct vkms_output *out)
> > {
> > struct drm_framebuffer *fb = &primary_crc->fb;
> > struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
> > @@ -130,6 +131,10 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *primary_crc,
> > }
> >
> > memcpy(vaddr_out, vkms_obj->vaddr, vkms_obj->gem.size);
> > + // TODO: Remove this copy from crc, and make this sort of operation
> > + // generic since we can use in different places
> > + memcpy(out->connector.base.state->writeback_job->fb,
> > + vkms_obj->vaddr, vkms_obj->gem.size);
> > mutex_unlock(&vkms_obj->pages_lock);
> >
> > if (cursor_crc)
> > @@ -193,7 +198,7 @@ void vkms_crc_work_handle(struct work_struct *work)
> > }
> >
> > if (primary_crc)
> > - crc32 = _vkms_get_crc(primary_crc, cursor_crc);
> > + crc32 = _vkms_get_crc(primary_crc, cursor_crc, out);
> >
> > frame_end = drm_crtc_accurate_vblank_count(crtc);
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> > index 177bbcb38306..d33ddcc40a29 100644
> > --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> > +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> > @@ -48,6 +48,8 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
> >
> > _vblank_handle(output);
> >
> > + drm_writeback_signal_completion(&output->connector, 0);
> > +
> > ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer,
> > output->period_ns);
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> > index 1c93990693e3..1e8184ad872f 100644
> > --- a/drivers/gpu/drm/vkms/vkms_drv.h
> > +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> > @@ -5,6 +5,7 @@
> > #include <drm/drm.h>
> > #include <drm/drm_gem.h>
> > #include <drm/drm_encoder.h>
> > +#include <drm/drm_writeback.h>
> > #include <linux/hrtimer.h>
> >
> > #define XRES_MIN 20
> > @@ -61,7 +62,7 @@ struct vkms_crtc_state {
> > struct vkms_output {
> > struct drm_crtc crtc;
> > struct drm_encoder encoder;
> > - struct drm_connector connector;
> > + struct drm_writeback_connector connector;
> > struct hrtimer vblank_hrtimer;
> > ktime_t period_ns;
> > struct drm_pending_vblank_event *event;
> > diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
> > index 271a0eb9042c..46622d012107 100644
> > --- a/drivers/gpu/drm/vkms/vkms_output.c
> > +++ b/drivers/gpu/drm/vkms/vkms_output.c
> > @@ -9,6 +9,13 @@
> > #include "vkms_drv.h"
> > #include <drm/drm_crtc_helper.h>
> > #include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_writeback.h>
> > +
> > +#define to_wb_state(_state) (struct vkms_writeback_connector_state *)(_state)
> > +
> > +struct vkms_writeback_connector_state {
> > + struct drm_connector_state base;
> > +};
> >
> > static void vkms_connector_destroy(struct drm_connector *connector)
> > {
> > @@ -16,11 +23,48 @@ static void vkms_connector_destroy(struct drm_connector *connector)
> > drm_connector_cleanup(connector);
> > }
> >
> > +static void vkms_connector_reset(struct drm_connector *connector)
> > +{
> > + struct vkms_writeback_connector_state *wb_state =
> > + kzalloc(sizeof(*wb_state), GFP_KERNEL);
> > +
> > + if (connector->state)
> > + __drm_atomic_helper_connector_destroy_state(connector->state);
> > +
> > + kfree(connector->state);
> > + __drm_atomic_helper_connector_reset(connector, &wb_state->base);
> > +}
> > +
> > +static struct drm_connector_state *
> > +vkms_connector_duplicate_state(struct drm_connector *connector)
> > +{
> > + struct vkms_writeback_connector_state *wb_state;
> > +
> > + if (WARN_ON(!connector->state))
> > + return NULL;
> > +
> > + wb_state = kzalloc(sizeof(*wb_state), GFP_KERNEL);
> > + if (!wb_state)
> > + return NULL;
> > +
> > + __drm_atomic_helper_connector_duplicate_state(connector,
> > + &wb_state->base);
> > +
> > + return &wb_state->base;
> > +}
> > +
> > +static enum drm_connector_status
> > +vkms_connector_detect(struct drm_connector *connector, bool force)
> > +{
> > + return connector_status_connected;
> > +}
> > +
> > static const struct drm_connector_funcs vkms_connector_funcs = {
> > + .reset = vkms_connector_reset,
> > + .detect = vkms_connector_detect,
> > .fill_modes = drm_helper_probe_single_connector_modes,
> > .destroy = vkms_connector_destroy,
> > - .reset = drm_atomic_helper_connector_reset,
> > - .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> > + .atomic_duplicate_state = vkms_connector_duplicate_state,
> > .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> > };
> >
> > @@ -42,12 +86,35 @@ static const struct drm_connector_helper_funcs vkms_conn_helper_funcs = {
> > .get_modes = vkms_conn_get_modes,
> > };
> >
> > +static int vkms_encoder_atomic_check(struct drm_encoder *encoder,
> > + struct drm_crtc_state *crtc_state,
> > + struct drm_connector_state *conn_state)
> > +{
> > + struct drm_framebuffer *fb;
> > +
> > + if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
> > + return 0;
> > +
> > + fb = conn_state->writeback_job->fb;
> > + if (fb->width != crtc_state->mode.hdisplay ||
> > + fb->height != crtc_state->mode.vdisplay) {
> > + DRM_DEBUG_KMS("Invalid framebuffer size %ux%u\n",
> > + fb->width, fb->height);
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static const struct drm_encoder_helper_funcs vkms_encoder_helper_funcs = {
> > + .atomic_check = vkms_encoder_atomic_check,
> > +};
> > +
> > int vkms_output_init(struct vkms_device *vkmsdev)
> > {
> > struct vkms_output *output = &vkmsdev->output;
> > struct drm_device *dev = &vkmsdev->drm;
> > - struct drm_connector *connector = &output->connector;
> > - struct drm_encoder *encoder = &output->encoder;
> > + struct drm_writeback_connector *connector = &output->connector;
> > struct drm_crtc *crtc = &output->crtc;
> > struct drm_plane *primary, *cursor = NULL;
> > int ret;
> > @@ -68,47 +135,29 @@ int vkms_output_init(struct vkms_device *vkmsdev)
> > if (ret)
> > goto err_crtc;
> >
> > - ret = drm_connector_init(dev, connector, &vkms_connector_funcs,
> > - DRM_MODE_CONNECTOR_VIRTUAL);
> > + ret = drm_writeback_connector_init(dev, connector,
> > + &vkms_connector_funcs,
> > + &vkms_encoder_helper_funcs,
> > + vkms_formats, 1);
> > if (ret) {
> > DRM_ERROR("Failed to init connector\n");
> > goto err_connector;
> > }
> >
> > - drm_connector_helper_add(connector, &vkms_conn_helper_funcs);
> > + drm_connector_helper_add(&connector->base, &vkms_conn_helper_funcs);
> >
> > - ret = drm_connector_register(connector);
> > + ret = drm_connector_register(&connector->base);
> > if (ret) {
> > DRM_ERROR("Failed to register connector\n");
> > goto err_connector_register;
> > }
> >
> > - ret = drm_encoder_init(dev, encoder, &vkms_encoder_funcs,
> > - DRM_MODE_ENCODER_VIRTUAL, NULL);
> > - if (ret) {
> > - DRM_ERROR("Failed to init encoder\n");
> > - goto err_encoder;
> > - }
> > - encoder->possible_crtcs = 1;
> > -
> > - ret = drm_connector_attach_encoder(connector, encoder);
> > - if (ret) {
> > - DRM_ERROR("Failed to attach connector to encoder\n");
> > - goto err_attach;
> > - }
> > -
> > drm_mode_config_reset(dev);
> >
> > return 0;
> >
> > -err_attach:
> > - drm_encoder_cleanup(encoder);
> > -
> > -err_encoder:
> > - drm_connector_unregister(connector);
> > -
> > err_connector_register:
> > - drm_connector_cleanup(connector);
> > + drm_connector_cleanup(&connector->base);
> >
> > err_connector:
> > drm_crtc_cleanup(crtc);
> > --
> > 2.19.1
> >
> >
> > --
> > Rodrigo Siqueira
> > https://siqueira.tech
> > https://twitter.com/siqueirajordao
> > Graduate Student
> > Department of Computer Science
> > University of São Paulo
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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