Message-ID: <20190516120221.GI14820@pendragon.ideasonboard.com>
Date:   Thu, 16 May 2019 15:02:21 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Sean Paul <sean@...rly.run>, dri-devel@...ts.freedesktop.org,
        Sean Paul <seanpaul@...omium.org>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Eric Anholt <eric@...olt.net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
        intel-gfx@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v3 04/10] drm: Convert
 connector_helper_funcs->atomic_check to accept drm_atomic_state

Hi Daniel,

On Mon, May 13, 2019 at 04:47:47PM +0200, Daniel Vetter wrote:
> On Sat, May 11, 2019 at 10:12:02PM +0300, Laurent Pinchart wrote:
> > On Thu, May 02, 2019 at 03:49:46PM -0400, Sean Paul wrote:
> >> From: Sean Paul <seanpaul@...omium.org>
> >> 
> >> Everyone who implements connector_helper_funcs->atomic_check reaches
> >> into the connector state to get the atomic state. Instead of continuing
> >> this pattern, change the callback signature to just give atomic state
> >> and let the driver determine what it does and does not need from it.
> >> 
> >> Eventually all atomic functions should do this, but that's just too much
> >> busy work for me.
> > 
> > Given that drivers also access the connector state, isn't this slightly
> > more inefficient ?
> 
> It's atomic code, we're trying to optimize for clean code at the expense
> of a bit of runtime overhead due to more pointer chasing. And I agree with
> the general push, the pile of old/new_state pointers of various objects
> we're passing around is confusing. Passing the overall drm_atomic_state
> seems much more reasonable, and with that we can get everything else. Plus
> it's much more obvious whether you have the old/new state (since that's
> explicit when you look it up from the drm_atomic_state).

Yes, I agree it's cleaner. I just hope the atomic state tracking cost
can be kept under control :-)

By the way, this is likely not going to happen as it would be way too
intrusive, but it would be nice to rename drm_atomic_state to
drm_atomic_transaction (or something similar). It doesn't model a state,
but a change between an old state to a new state. This confused me in
the past, and I'm sure it can still be confusing to newcomers.

> If we ever see this show up in profile, and it starts mattering, first
> thing we need is a hashtable I think (atm it's list walking, which is just
> terrible). But thus far no one cares.
> 
> >> Changes in v3:
> >> - Added to the set
> >> 
> >> Cc: Daniel Vetter <daniel@...ll.ch>
> >> Cc: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> >> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> >> Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
> >> Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
> >> Cc: Ben Skeggs <bskeggs@...hat.com>
> >> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> >> Cc: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> >> Cc: Eric Anholt <eric@...olt.net>
> >> Signed-off-by: Sean Paul <seanpaul@...omium.org>
> >> ---
> >>  drivers/gpu/drm/drm_atomic_helper.c      |  4 ++--
> >>  drivers/gpu/drm/i915/intel_atomic.c      |  8 +++++---
> >>  drivers/gpu/drm/i915/intel_dp_mst.c      |  7 ++++---
> >>  drivers/gpu/drm/i915/intel_drv.h         |  2 +-
> >>  drivers/gpu/drm/i915/intel_sdvo.c        |  9 +++++----
> >>  drivers/gpu/drm/i915/intel_tv.c          |  8 +++++---
> >>  drivers/gpu/drm/nouveau/dispnv50/disp.c  |  5 +++--
> >>  drivers/gpu/drm/rcar-du/rcar_lvds.c      | 12 +++++++-----
> >>  drivers/gpu/drm/vc4/vc4_txp.c            |  7 ++++---
> >>  include/drm/drm_modeset_helper_vtables.h |  2 +-
> >>  10 files changed, 37 insertions(+), 27 deletions(-)
> >> 
> >> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> >> index 9d9e47276839..fa5a367507c1 100644
> >> --- a/drivers/gpu/drm/drm_atomic_helper.c
> >> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> >> @@ -683,7 +683,7 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
> >>  		}
> >>  
> >>  		if (funcs->atomic_check)
> >> -			ret = funcs->atomic_check(connector, new_connector_state);
> >> +			ret = funcs->atomic_check(connector, state);
> >>  		if (ret)
> >>  			return ret;
> >>  
> >> @@ -725,7 +725,7 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
> >>  			continue;
> >>  
> >>  		if (funcs->atomic_check)
> >> -			ret = funcs->atomic_check(connector, new_connector_state);
> >> +			ret = funcs->atomic_check(connector, state);
> >>  		if (ret)
> >>  			return ret;
> >>  	}
> >> diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c
> >> index b844e8840c6f..e8a5b82e9242 100644
> >> --- a/drivers/gpu/drm/i915/intel_atomic.c
> >> +++ b/drivers/gpu/drm/i915/intel_atomic.c
> >> @@ -103,12 +103,14 @@ int intel_digital_connector_atomic_set_property(struct drm_connector *connector,
> >>  }
> >>  
> >>  int intel_digital_connector_atomic_check(struct drm_connector *conn,
> >> -					 struct drm_connector_state *new_state)
> >> +					 struct drm_atomic_state *state)
> >>  {
> >> +	struct drm_connector_state *new_state =
> >> +		drm_atomic_get_new_connector_state(state, conn);
> >>  	struct intel_digital_connector_state *new_conn_state =
> >>  		to_intel_digital_connector_state(new_state);
> >>  	struct drm_connector_state *old_state =
> >> -		drm_atomic_get_old_connector_state(new_state->state, conn);
> >> +		drm_atomic_get_old_connector_state(state, conn);
> >>  	struct intel_digital_connector_state *old_conn_state =
> >>  		to_intel_digital_connector_state(old_state);
> >>  	struct drm_crtc_state *crtc_state;
> >> @@ -118,7 +120,7 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
> >>  	if (!new_state->crtc)
> >>  		return 0;
> >>  
> >> -	crtc_state = drm_atomic_get_new_crtc_state(new_state->state, new_state->crtc);
> >> +	crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
> >>  
> >>  	/*
> >>  	 * These properties are handled by fastset, and might not end
> >> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> >> index 19d81cef2ab6..89cfec128ba0 100644
> >> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> >> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> >> @@ -143,9 +143,10 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
> >>  
> >>  static int
> >>  intel_dp_mst_atomic_check(struct drm_connector *connector,
> >> -			  struct drm_connector_state *new_conn_state)
> >> +			  struct drm_atomic_state *state)
> >>  {
> >> -	struct drm_atomic_state *state = new_conn_state->state;
> >> +	struct drm_connector_state *new_conn_state =
> >> +		drm_atomic_get_new_connector_state(state, connector);
> >>  	struct drm_connector_state *old_conn_state =
> >>  		drm_atomic_get_old_connector_state(state, connector);
> >>  	struct intel_connector *intel_connector =
> >> @@ -155,7 +156,7 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
> >>  	struct drm_dp_mst_topology_mgr *mgr;
> >>  	int ret;
> >>  
> >> -	ret = intel_digital_connector_atomic_check(connector, new_conn_state);
> >> +	ret = intel_digital_connector_atomic_check(connector, state);
> >>  	if (ret)
> >>  		return ret;
> >>  
> >> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> >> index f8c7b291fdc3..88571b8e8d62 100644
> >> --- a/drivers/gpu/drm/i915/intel_drv.h
> >> +++ b/drivers/gpu/drm/i915/intel_drv.h
> >> @@ -2481,7 +2481,7 @@ int intel_digital_connector_atomic_set_property(struct drm_connector *connector,
> >>  						struct drm_property *property,
> >>  						u64 val);
> >>  int intel_digital_connector_atomic_check(struct drm_connector *conn,
> >> -					 struct drm_connector_state *new_state);
> >> +					 struct drm_atomic_state *state);
> >>  struct drm_connector_state *
> >>  intel_digital_connector_duplicate_state(struct drm_connector *connector);
> >>  
> >> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> >> index 68f497493d43..72ea164b971c 100644
> >> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> >> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> >> @@ -2342,9 +2342,10 @@ static const struct drm_connector_funcs intel_sdvo_connector_funcs = {
> >>  };
> >>  
> >>  static int intel_sdvo_atomic_check(struct drm_connector *conn,
> >> -				   struct drm_connector_state *new_conn_state)
> >> +				   struct drm_atomic_state *state)
> >>  {
> >> -	struct drm_atomic_state *state = new_conn_state->state;
> >> +	struct drm_connector_state *new_conn_state =
> >> +		drm_atomic_get_new_connector_state(state, conn);
> >>  	struct drm_connector_state *old_conn_state =
> >>  		drm_atomic_get_old_connector_state(state, conn);
> >>  	struct intel_sdvo_connector_state *old_state =
> >> @@ -2356,13 +2357,13 @@ static int intel_sdvo_atomic_check(struct drm_connector *conn,
> >>  	    (memcmp(&old_state->tv, &new_state->tv, sizeof(old_state->tv)) ||
> >>  	     memcmp(&old_conn_state->tv, &new_conn_state->tv, sizeof(old_conn_state->tv)))) {
> >>  		struct drm_crtc_state *crtc_state =
> >> -			drm_atomic_get_new_crtc_state(new_conn_state->state,
> >> +			drm_atomic_get_new_crtc_state(state,
> >>  						      new_conn_state->crtc);
> >>  
> >>  		crtc_state->connectors_changed = true;
> >>  	}
> >>  
> >> -	return intel_digital_connector_atomic_check(conn, new_conn_state);
> >> +	return intel_digital_connector_atomic_check(conn, state);
> >>  }
> >>  
> >>  static const struct drm_connector_helper_funcs intel_sdvo_connector_helper_funcs = {
> >> diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> >> index 3924c4944e1f..a41c5b467c14 100644
> >> --- a/drivers/gpu/drm/i915/intel_tv.c
> >> +++ b/drivers/gpu/drm/i915/intel_tv.c
> >> @@ -1817,16 +1817,18 @@ static const struct drm_connector_funcs intel_tv_connector_funcs = {
> >>  };
> >>  
> >>  static int intel_tv_atomic_check(struct drm_connector *connector,
> >> -				 struct drm_connector_state *new_state)
> >> +				 struct drm_atomic_state *state)
> >>  {
> >> +	struct drm_connector_state *new_state;
> >>  	struct drm_crtc_state *new_crtc_state;
> >>  	struct drm_connector_state *old_state;
> >>  
> >> +	new_state = drm_atomic_get_new_connector_state(state, connector);
> >>  	if (!new_state->crtc)
> >>  		return 0;
> >>  
> >> -	old_state = drm_atomic_get_old_connector_state(new_state->state, connector);
> >> -	new_crtc_state = drm_atomic_get_new_crtc_state(new_state->state, new_state->crtc);
> >> +	old_state = drm_atomic_get_old_connector_state(state, connector);
> >> +	new_crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
> >>  
> >>  	if (old_state->tv.mode != new_state->tv.mode ||
> >>  	    old_state->tv.margins.left != new_state->tv.margins.left ||
> >> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> >> index 4b1650f51955..7ba373f493b2 100644
> >> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> >> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> >> @@ -948,11 +948,12 @@ nv50_mstc_get_modes(struct drm_connector *connector)
> >>  
> >>  static int
> >>  nv50_mstc_atomic_check(struct drm_connector *connector,
> >> -		       struct drm_connector_state *new_conn_state)
> >> +		       struct drm_atomic_state *state)
> >>  {
> >> -	struct drm_atomic_state *state = new_conn_state->state;
> >>  	struct nv50_mstc *mstc = nv50_mstc(connector);
> >>  	struct drm_dp_mst_topology_mgr *mgr = &mstc->mstm->mgr;
> >> +	struct drm_connector_state *new_conn_state =
> >> +		drm_atomic_get_new_connector_state(state, connector);
> >>  	struct drm_connector_state *old_conn_state =
> >>  		drm_atomic_get_old_connector_state(state, connector);
> >>  	struct drm_crtc_state *crtc_state;
> >> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> >> index 620b51aab291..5b81ba2a7f27 100644
> >> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> >> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> >> @@ -92,13 +92,15 @@ static int rcar_lvds_connector_get_modes(struct drm_connector *connector)
> >>  }
> >>  
> >>  static int rcar_lvds_connector_atomic_check(struct drm_connector *connector,
> >> -					    struct drm_connector_state *state)
> >> +					    struct drm_atomic_state *state)
> >>  {
> >>  	struct rcar_lvds *lvds = connector_to_rcar_lvds(connector);
> >>  	const struct drm_display_mode *panel_mode;
> >> +	struct drm_connector_state *conn_state;
> >>  	struct drm_crtc_state *crtc_state;
> >>  
> >> -	if (!state->crtc)
> >> +	conn_state = drm_atomic_get_new_connector_state(state, connector);
> >> +	if (!conn_state->crtc)
> >>  		return 0;
> >>  
> >>  	if (list_empty(&connector->modes)) {
> >> @@ -110,9 +112,9 @@ static int rcar_lvds_connector_atomic_check(struct drm_connector *connector,
> >>  				      struct drm_display_mode, head);
> >>  
> >>  	/* We're not allowed to modify the resolution. */
> >> -	crtc_state = drm_atomic_get_crtc_state(state->state, state->crtc);
> >> -	if (IS_ERR(crtc_state))
> >> -		return PTR_ERR(crtc_state);
> >> +	crtc_state = drm_atomic_get_crtc_state(state, conn_state->crtc);
> >> +	if (!crtc_state)
> >> +		return -EINVAL;
> >>  
> >>  	if (crtc_state->mode.hdisplay != panel_mode->hdisplay ||
> >>  	    crtc_state->mode.vdisplay != panel_mode->vdisplay)
> >> diff --git a/drivers/gpu/drm/vc4/vc4_txp.c b/drivers/gpu/drm/vc4/vc4_txp.c
> >> index c8b89a78f9f4..96f91c1b4b6e 100644
> >> --- a/drivers/gpu/drm/vc4/vc4_txp.c
> >> +++ b/drivers/gpu/drm/vc4/vc4_txp.c
> >> @@ -221,17 +221,18 @@ static const u32 txp_fmts[] = {
> >>  };
> >>  
> >>  static int vc4_txp_connector_atomic_check(struct drm_connector *conn,
> >> -					struct drm_connector_state *conn_state)
> >> +					  struct drm_atomic_state *state)
> >>  {
> >> +	struct drm_connector_state *conn_state;
> >>  	struct drm_crtc_state *crtc_state;
> >>  	struct drm_framebuffer *fb;
> >>  	int i;
> >>  
> >> +	conn_state = drm_atomic_get_new_connector_state(state, conn);
> >>  	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
> >>  		return 0;
> >>  
> >> -	crtc_state = drm_atomic_get_new_crtc_state(conn_state->state,
> >> -						   conn_state->crtc);
> >> +	crtc_state = drm_atomic_get_new_crtc_state(state, conn_state->crtc);
> >>  
> >>  	fb = conn_state->writeback_job->fb;
> >>  	if (fb->width != crtc_state->mode.hdisplay ||
> >> diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
> >> index de57fb40cb6e..adc8b7cf64b5 100644
> >> --- a/include/drm/drm_modeset_helper_vtables.h
> >> +++ b/include/drm/drm_modeset_helper_vtables.h
> >> @@ -1020,7 +1020,7 @@ struct drm_connector_helper_funcs {
> >>  	 * deadlock.
> >>  	 */
> >>  	int (*atomic_check)(struct drm_connector *connector,
> >> -			    struct drm_connector_state *state);
> >> +			    struct drm_atomic_state *state);
> >>  
> >>  	/**
> >>  	 * @atomic_commit:

-- 
Regards,

Laurent Pinchart

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