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Date: Mon, 15 May 2017 11:30:51 +0200
From: Daniel Vetter <daniel@...ll.ch>
To: Andrzej Hajda <a.hajda@...sung.com>
Cc: Jose Abreu <Jose.Abreu@...opsys.com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Carlos Palminha <CARLOS.PALMINHA@...opsys.com>,
Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
Ville Syrjälä
<ville.syrjala@...ux.intel.com>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Dave Airlie <airlied@...ux.ie>,
Archit Taneja <architt@...eaurora.org>
Subject: Re: [PATCH v3 4/6] drm: Use new mode_valid() helpers in connector
probe helper
On Mon, May 15, 2017 at 10:39:35AM +0200, Andrzej Hajda wrote:
> On 11.05.2017 11:06, Jose Abreu wrote:
> > This changes the connector probe helper function to use the new
> > encoder->mode_valid(), bridge->mode_valid() and crtc->mode_valid()
> > helper callbacks to validate the modes.
> >
> > The new callbacks are optional so the behaviour remains the same
> > if they are not implemented. If they are, then the code loops
> > through all the connector's encodersXbridgesXcrtcs and calls the
> > callback.
> >
> > If at least a valid encoderXbridgeXcrtc combination is found which
> > accepts the mode then the function returns MODE_OK.
> >
> > Signed-off-by: Jose Abreu <joabreu@...opsys.com>
> > Cc: Carlos Palminha <palminha@...opsys.com>
> > Cc: Alexey Brodkin <abrodkin@...opsys.com>
> > Cc: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> > Cc: Dave Airlie <airlied@...ux.ie>
> > Cc: Andrzej Hajda <a.hajda@...sung.com>
> > Cc: Archit Taneja <architt@...eaurora.org>
> > ---
> >
> > Changes v2->v3:
> > - Call also bridge->mode_valid (Daniel)
> > Changes v1->v2:
> > - Use new helpers suggested by Ville
> > - Change documentation (Daniel)
> >
> > drivers/gpu/drm/drm_probe_helper.c | 65 ++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 62 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> > index f01abdc..84d660e 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -83,6 +83,61 @@
> > return MODE_OK;
> > }
> >
> > +static enum drm_mode_status
> > +drm_mode_validate_connector(struct drm_connector *connector,
> > + struct drm_display_mode *mode)
> > +{
> > + struct drm_device *dev = connector->dev;
> > + uint32_t *ids = connector->encoder_ids;
> > + enum drm_mode_status ret = MODE_OK;
> > + unsigned int i;
> > +
> > + /* Step 1: Validate against connector */
> > + ret = drm_connector_mode_valid(connector, mode);
> > + if (ret != MODE_OK)
> > + return ret;
> > +
> > + /* Step 2: Validate against encoders and crtcs */
> > + for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> > + struct drm_encoder *encoder = drm_encoder_find(dev, ids[i]);
> > + struct drm_crtc *crtc;
> > +
> > + if (!encoder)
> > + continue;
> > +
> > + ret = drm_encoder_mode_valid(encoder, mode);
> > + if (ret != MODE_OK) {
> > + /* No point in continuing for crtc check as this encoder
> > + * will not accept the mode anyway. If all encoders
> > + * reject the mode then, at exit, ret will not be
> > + * MODE_OK. */
> > + continue;
> > + }
> > +
> > + ret = drm_bridge_mode_valid(encoder->bridge, mode);
> > + if (ret != MODE_OK) {
> > + /* There is also no point in continuing for crtc check
> > + * here. */
> > + continue;
> > + }
>
> Maybe it is a bikeshedding, but wouldn't be better to call
> drm_bridge_mode_valid from drm_encoder_mode_valid, in general call all
> bridge related stuff from corresponding encoder stuff?
> This is more question about role of encoder->bridge, should it be
> treated as encoder's extension, or as 1st class citizen in drm?
>
> Another concern is about order of calls, it is from sink to source, to
> keep it consistent bridge should be called before encoder, am I right?
For the atomic_check stuff (where we do change the passed-in mode) this
would be correct, and calling order and layering would matter. But this
just validates the mode in turn with everything, not taking any
cross-component constraint or other configuration-dependent constraints
into account. Hence it doesn't matter in which order we call stuff.
Note that the passed-in mode is const, so you can't escape. And v3 of
patch 1 now has added wording that you're not allowed to look at anything
else dynamie either.
Does that address your concern?
-Daniel
> Beside this:
> Reviewed-by: Andrzej Hajda <a.hajda@...sung.com>
>
> --
> Regards
> Andrzej
>
> > +
> > + drm_for_each_crtc(crtc, dev) {
> > + if (!drm_encoder_crtc_ok(encoder, crtc))
> > + continue;
> > +
> > + ret = drm_crtc_mode_valid(crtc, mode);
> > + if (ret == MODE_OK) {
> > + /* If we get to this point there is at least
> > + * one combination of encoder+crtc that works
> > + * for this mode. Lets return now. */
> > + return ret;
> > + }
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
> > {
> > struct drm_cmdline_mode *cmdline_mode;
> > @@ -322,7 +377,11 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
> > * - drm_mode_validate_flag() checks the modes against basic connector
> > * capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
> > * - the optional &drm_connector_helper_funcs.mode_valid helper can perform
> > - * driver and/or hardware specific checks
> > + * driver and/or sink specific checks
> > + * - the optional &drm_crtc_helper_funcs.mode_valid,
> > + * &drm_bridge_funcs.mode_valid and &drm_encoder_helper_funcs.mode_valid
> > + * helpers can perform driver and/or source specific checks which are also
> > + * enforced by the modeset/atomic helpers
> > *
> > * 5. Any mode whose status is not OK is pruned from the connector's modes list,
> > * accompanied by a debug message indicating the reason for the mode's
> > @@ -466,8 +525,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> > if (mode->status == MODE_OK)
> > mode->status = drm_mode_validate_flag(mode, mode_flags);
> >
> > - if (mode->status == MODE_OK && connector_funcs->mode_valid)
> > - mode->status = connector_funcs->mode_valid(connector,
> > + if (mode->status == MODE_OK)
> > + mode->status = drm_mode_validate_connector(connector,
> > mode);
> > }
> >
>
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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