On 24-03-22 09:30:21, Bjorn Andersson wrote:
> On Fri, Mar 22, 2024 at 03:22:22PM +0200, Abel Vesa wrote:
> > Instead of relying on different compatibles for eDP and DP, lookup
> > the panel node in devicetree to figure out the connector type and
> > then pass on that information to the PHY. External DP is not described
> > in DT, therefore, assume it's eDP if panel node is present.
> >
> > Signed-off-by: Abel Vesa <abel.v...@linaro.org>
> > ---
> > drivers/gpu/drm/msm/dp/dp_display.c | 43
> > +++++++++++++++++++++++++++++++++----
> > 1 file changed, 39 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> > b/drivers/gpu/drm/msm/dp/dp_display.c
> > index c4cb82af5c2f..c9763f77c832 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -726,6 +726,14 @@ static int dp_init_sub_modules(struct
> > dp_display_private *dp)
> > if (IS_ERR(phy))
> > return PTR_ERR(phy);
> >
> > + rc = phy_set_mode_ext(phy, PHY_MODE_DP,
> > + dp->dp_display.is_edp ? PHY_SUBMODE_EDP :
> > PHY_SUBMODE_DP);
> > + if (rc) {
> > + DRM_ERROR("failed to set phy submode, rc = %d\n", rc);
> > + dp->catalog = NULL;
> > + goto error;
> > + }
> > +
> > dp->catalog = dp_catalog_get(dev);
> > if (IS_ERR(dp->catalog)) {
> > rc = PTR_ERR(dp->catalog);
> > @@ -734,9 +742,7 @@ static int dp_init_sub_modules(struct
> > dp_display_private *dp)
> > goto error;
> > }
> >
> > - dp->aux = dp_aux_get(dev, dp->catalog,
> > - phy,
> > - dp->dp_display.is_edp);
> > + dp->aux = dp_aux_get(dev, dp->catalog, phy, dp->dp_display.is_edp);
> > if (IS_ERR(dp->aux)) {
> > rc = PTR_ERR(dp->aux);
> > DRM_ERROR("failed to initialize aux, rc = %d\n", rc);
> > @@ -1241,6 +1247,35 @@ static int dp_auxbus_done_probe(struct drm_dp_aux
> > *aux)
> > return dp_display_probe_tail(aux->dev);
> > }
> >
> > +static int dp_display_get_connector_type(struct platform_device *pdev,
> > + const struct msm_dp_desc *desc)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct device_node *aux_bus;
> > + struct device_node *panel;
> > + int ret = DRM_MODE_CONNECTOR_DisplayPort;
> > +
> > + /* legacy platforms specify connector type in match data */
> > + if (desc->connector_type == DRM_MODE_CONNECTOR_eDP ||
> > + desc->connector_type == DRM_MODE_CONNECTOR_DisplayPort)
> > + return desc->connector_type;
> > +
> > + aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> > + if (!aux_bus)
> > + goto out;
>
> My compiler warns that if we take this code path, then you will
> of_node_put(<uninitialized panel>) below.
>
> > +
> > + panel = of_get_child_by_name(aux_bus, "panel");
> > + if (!panel)
> > + goto out;
> > +
> > + ret = DRM_MODE_CONNECTOR_eDP;
>
> My brain read this function as:
> check something
> if (error)
> bailout!
>
> check something
> if (error)
> bailout!
>
> ret should be edp
>
> I then have to scan the code again to figure out what ret is otherwise,
> and convince myself that the error path is never an error, but a totally
> normal case.
>
>
> If you instead rely on the fact that both of_get_child_by_name() and
> of_node_put() can be passed NULL, you can write this as:
>
> static int fn(..) {
> aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> panel = of_get_child_by_name(aux_bus, "panel");
>
> if (panel)
> connector_type = DRM_MODE_CONNECTOR_eDP;
> else
> connector_type = DRM_MODE_CONNECTOR_DisplayPort;
>
> of_node_put(panel);
> of_node_put(aux_bus);
>
> return connector_type;
> }
>
> Much easier to read, and you don't even have to zero-initialize panel to
> avoid that compiler warning.
>
Fair enough, will do that instead.
> Regards,
> Bjorn
>
> > +
> > +out:
> > + of_node_put(panel);
> > + of_node_put(aux_bus);
> > + return ret;
> > +}
> > +
> > static int dp_display_probe(struct platform_device *pdev)
> > {
> > int rc = 0;
> > @@ -1263,7 +1298,7 @@ static int dp_display_probe(struct platform_device
> > *pdev)
> > dp->dp_display.pdev = pdev;
> > dp->name = "drm_dp";
> > dp->id = desc->id;
> > - dp->dp_display.connector_type = desc->connector_type;
> > + dp->dp_display.connector_type = dp_display_get_connector_type(pdev,
> > desc);
> > dp->wide_bus_supported = desc->wide_bus_supported;
> > dp->dp_display.is_edp =
> > (dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP);
> >
> > --
> > 2.34.1
> >
