Quoting Hsin-Yi Wang (2022-06-06 08:24:24)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c index f634371c717a..e12056cfeca8 100644 --- a/drivers/gpu/drm/drm_panel.c +++ b/drivers/gpu/drm/drm_panel.c @@ -223,6 +223,15 @@ int drm_panel_get_modes(struct drm_panel *panel, } EXPORT_SYMBOL(drm_panel_get_modes);

+enum drm_panel_orientation drm_panel_get_orientation(struct drm_panel *panel)

Should 'panel' be marked const to indicate that it can't be modified?

+{

•   if (panel && panel->funcs && panel->funcs->get_orientation)
  

•           return panel->funcs->get_orientation(panel);
  

Hi Hsin-Yi, On Mon, Jun 06, 2022 at 11:24:24PM +0800, Hsin-Yi Wang wrote:

Panels usually call drm_connector_set_panel_orientation(), which is later than drm/kms driver calling drm_dev_register(). This leads to a WARN().

The orientation property is known earlier. For example, some panels parse the property through device tree during probe.

Add an API to return the property from panel to drm/kms driver, so the drivers are able to call drm_connector_set_panel_orientation() before drm_dev_register().

Suggested-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Hsin-Yi Wang hsinyi@chromium.org Reviewed-by: Hans de Goede hdegoede@redhat.com Reviewed-by: Douglas Anderson dianders@chromium.org

---

v3->v4: Add a blank line.

drivers/gpu/drm/drm_panel.c | 9 +++++++++ include/drm/drm_panel.h | 10 ++++++++++ 2 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c index f634371c717a..e12056cfeca8 100644 --- a/drivers/gpu/drm/drm_panel.c +++ b/drivers/gpu/drm/drm_panel.c @@ -223,6 +223,15 @@ int drm_panel_get_modes(struct drm_panel *panel, } EXPORT_SYMBOL(drm_panel_get_modes);

+enum drm_panel_orientation drm_panel_get_orientation(struct drm_panel *panel)

const as mentioned by Stephen.

+{

• if (panel && panel->funcs && panel->funcs->get_orientation)

• return panel->funcs->get_orientation(panel);
  

• return DRM_MODE_PANEL_ORIENTATION_UNKNOWN;

+} +EXPORT_SYMBOL(drm_panel_get_orientation);

#ifdef CONFIG_OF /**

• of_drm_find_panel - look up a panel using a device tree node

diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h index d279ee455f01..5dadbf3b0370 100644 --- a/include/drm/drm_panel.h +++ b/include/drm/drm_panel.h @@ -133,6 +133,15 @@ struct drm_panel_funcs { * Allows panels to create panels-specific debugfs files. */ void (*debugfs_init)(struct drm_panel *panel, struct dentry *root);

• /**

• * @get_orientation:
  

• *
  

• * Return the panel orientation set by device tree or EDID.
  

• *
  

• * This function is optional.
  

• */
  

• enum drm_panel_orientation (*get_orientation)(struct drm_panel *panel);

Please move this up so it is together with the other get_* methods, in alphabetic order. That is, right after get_modes(), and then this also matches the order in the .c file with is extra bonus.

With the two fixes: Reviewed-by: Sam Ravnborg sam@ravnborg.org

};

/** @@ -202,6 +211,7 @@ int drm_panel_enable(struct drm_panel *panel); int drm_panel_disable(struct drm_panel *panel);

int drm_panel_get_modes(struct drm_panel *panel, struct drm_connector *connector); +enum drm_panel_orientation drm_panel_get_orientation(struct drm_panel *panel);

#if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL) struct drm_panel *of_drm_find_panel(const struct device_node *np); -- 2.36.1.255.ge46751e96f-goog

Quoting Hsin-Yi Wang (2022-06-06 08:24:27)

diff --git a/drivers/gpu/drm/panel/panel-lvds.c b/drivers/gpu/drm/panel/panel-lvds.c index f11252fb00fe..491b64c2c8d6 100644 --- a/drivers/gpu/drm/panel/panel-lvds.c +++ b/drivers/gpu/drm/panel/panel-lvds.c @@ -99,15 +99,30 @@ static int panel_lvds_get_modes(struct drm_panel *panel, drm_display_info_set_bus_formats(&connector->display_info, &lvds->bus_format, 1); connector->display_info.bus_flags = lvds->bus_flags;

•   /*
  

•    * drm drivers are expected to call drm_panel_get_orientation() to get
  

•    * panel's orientation then drm_connector_set_panel_orientation() to
  

•    * set the property before drm_dev_register(). Otherwise there will be
  

•    * a WARN_ON if orientation is set after drm is registered.
  

•    */
  

Should this comment also be a "TODO: Remove once all drm drivers call drm_connector_set_panel_orientation()"?

    drm_connector_set_panel_orientation(connector, lvds->orientation);

    return 1;

}

+static enum drm_panel_orientation panel_lvds_get_orientation,(struct drm_panel *panel)

Stray comma here ---^

+{

•   struct panel_lvds *lvds = to_panel_lvds(panel);
  

•   return lvds->orientation;
  

+}

Hi Hsin-Yi,

On Mon, Jun 06, 2022 at 11:24:28PM +0800, Hsin-Yi Wang wrote:

To return the orientation property to drm/kms driver.

Signed-off-by: Hsin-Yi Wang hsinyi@chromium.org Reviewed-by: Hans de Goede hdegoede@redhat.com Reviewed-by: Douglas Anderson dianders@chromium.org

---

drivers/gpu/drm/panel/panel-simple.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 4a2e580a2f7b..f232b8cf4075 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -411,7 +411,12 @@ static int panel_simple_get_modes(struct drm_panel *panel, /* add hard-coded panel modes */ num += panel_simple_get_non_edid_modes(p, connector);

• /* set up connector's "panel orientation" property */

• /*

• * drm drivers are expected to call drm_panel_get_orientation() to get
  

• * panel's orientation then drm_connector_set_panel_orientation() to
  

• * set the property before drm_dev_register(). Otherwise there will be
  

• * a WARN_ON if orientation is set after drm is registered.
  

• */
  

This comment is not really relevant here. If we need to explain this then put it in drm_panel.c/h - as this applies for all panels and not just the panel_simple. Keep in mind, this is the source new panels often use a inspiration and no need to have this copied around.

drm_connector_set_panel_orientation(connector, p->orientation);

return num; @@ -434,6 +439,14 @@ static int panel_simple_get_timings(struct drm_panel *panel, return p->desc->num_timings; }

+static enum drm_panel_orientation panel_simple_get_orientation(struct drm_panel *panel) +{

•   struct panel_simple *p = to_panel_simple(panel);
  

•   return p->orientation;
  

+}

static const struct drm_panel_funcs panel_simple_funcs = { .disable = panel_simple_disable, .unprepare = panel_simple_unprepare, @@ -441,6 +454,7 @@ static const struct drm_panel_funcs panel_simple_funcs = { .enable = panel_simple_enable, .get_modes = panel_simple_get_modes, .get_timings = panel_simple_get_timings,

• .get_orientation = panel_simple_get_orientation,

I like the order in this list to match the order in the .h file. So my OCD would like you to move it up right after get_modes, but feel free to ignore this.

With the suggested changes: Reviewed-by: Sam Ravnborg sam@ravnborg.org

};

static struct panel_desc panel_dpi;

2.36.1.255.ge46751e96f-goog

On Tue, Jun 7, 2022 at 3:16 AM Stephen Boyd swboyd@chromium.org wrote:

Quoting Hsin-Yi Wang (2022-06-06 08:24:31)

...

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index d9f10a33e6fa..c56282412bfa 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -822,6 +823,12 @@ static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) ret = PTR_ERR(dsi->connector); goto err_cleanup_encoder; }

•   /* Read panel orientation */
  

•   if (dsi->panel)
  

•           drm_connector_set_panel_orientation(dsi->connector,
  

•                           drm_panel_get_orientation(dsi->panel));
  

It could be simplified like so?

    drm_connector_set_orientation_from_panel(dsi->connector, dsi->panel);

Then the API could get the orientation if the panel pointer is valid. Does any code need to use/modify the orientation value besides drm_connector_set_panel_orientation()?

We can add another function to call drm_connector_set_orientation_from_panel(), which will be like

void drm_connector_set_orientation_from_panel(connector, panel) { if (panel) drm_connector_set_panel_orientation(connector,drm_panel_get_orientation(panel)); }

Though it's very should but I can add this if this can make the caller more convenient.

...

    drm_connector_attach_encoder(dsi->connector, &dsi->encoder);

    return 0;

On Tue, Jun 7, 2022 at 3:31 AM Sam Ravnborg sam@ravnborg.org wrote:

Hi Hsin-Yi,

On Mon, Jun 06, 2022 at 11:24:31PM +0800, Hsin-Yi Wang wrote:

...

Panel orientation property should be set before drm_dev_register(). Mediatek drm driver calls drm_dev_register() in .bind(). However, most panels sets orientation property relatively late, mostly in .get_modes() callback, since this is when they are able to get the connector and binds the orientation property to it, though the value should be known when the panel is probed.

Let the drm driver check if the remote end point is a panel and if it contains the orientation property. If it does, set it before drm_dev_register() is called.

I do not know the best way to do what you need to do here. But it seems wrong to introduce a deprecated function (drm_of_find_panel_or_bridge), to set the rotation property early.

How about of_drm_find_panel()?

I think you need to find a way to do this utilising the panel_bridge or something.

    Sam

...

Signed-off-by: Hsin-Yi Wang hsinyi@chromium.org Reviewed-by: Hans de Goede hdegoede@redhat.com Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com

---

drivers/gpu/drm/mediatek/mtk_dsi.c | 10 ++++++++++ 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index d9f10a33e6fa..c56282412bfa 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -185,6 +185,7 @@ struct mtk_dsi { struct drm_encoder encoder; struct drm_bridge bridge; struct drm_bridge *next_bridge;

• struct drm_panel *panel;
  struct drm_connector *connector;
  struct phy *phy;
  
  

@@ -822,6 +823,12 @@ static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) ret = PTR_ERR(dsi->connector); goto err_cleanup_encoder; }

• /* Read panel orientation */
  

• if (dsi->panel)
  

•         drm_connector_set_panel_orientation(dsi->connector,
  

•                         drm_panel_get_orientation(dsi->panel));
  

• drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
  
  return 0;
  

@@ -837,6 +844,9 @@ static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) struct drm_device *drm = data; struct mtk_dsi *dsi = dev_get_drvdata(dev);

• /* Get panel if existed */
  

• drm_of_find_panel_or_bridge(dev->of_node, 0, 0, &dsi->panel, NULL);
  

• ret = mtk_dsi_encoder_init(drm, dsi);
  if (ret)
          return ret;
  

-- 2.36.1.255.ge46751e96f-goog