Hi
Am 12.07.21 um 11:41 schrieb Thomas Zimmermann:
Am 26.06.21 um 18:51 schrieb Rajeev Nandan:
Some panels support backlight control over DP AUX channel using VESA's standard backlight control interface. Using new DRM eDP backlight helpers, add support to create and register a backlight for those panels in drm_panel to simplify the panel drivers.
The panel driver with access to "struct drm_dp_aux" can create and register a backlight device using following code snippet in its probe() function:
err = drm_panel_dp_aux_backlight(panel, aux); if (err) return err;
Then drm_panel will handle backlight_(enable|disable) calls similar to the case when drm_panel_of_backlight() is used.
Currently, we are not supporting one feature where the source device can combine the backlight brightness levels set through DP AUX and the BL_PWM_DIM eDP connector pin. Since it's not required for the basic backlight controls, it can be added later.
Signed-off-by: Rajeev Nandan rajeevny@codeaurora.org Reviewed-by: Douglas Anderson dianders@chromium.org Reviewed-by: Lyude Paul lyude@redhat.com
Changes in v5:
- New
Changes in v6:
- Fixed ordering of memory allocation (Douglas)
- Updated word wrapping in a comment (Douglas)
Changes in v8:
- Now using backlight_is_blank() to get the backlight blank status
(Sam Ravnborg)
drivers/gpu/drm/drm_panel.c | 108 ++++++++++++++++++++++++++++++++++++++++++++ include/drm/drm_panel.h | 15 ++++-- 2 files changed, 119 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c index f634371..4fa1e3b 100644 --- a/drivers/gpu/drm/drm_panel.c +++ b/drivers/gpu/drm/drm_panel.c @@ -26,12 +26,20 @@ #include <linux/module.h> #include <drm/drm_crtc.h> +#include <drm/drm_dp_helper.h> #include <drm/drm_panel.h> #include <drm/drm_print.h> static DEFINE_MUTEX(panel_lock); static LIST_HEAD(panel_list); +struct dp_aux_backlight { + struct backlight_device *base; + struct drm_dp_aux *aux; + struct drm_edp_backlight_info info; + bool enabled; +};
/** * DOC: drm panel * @@ -342,6 +350,106 @@ int drm_panel_of_backlight(struct drm_panel *panel) return 0; } EXPORT_SYMBOL(drm_panel_of_backlight);
+static int dp_aux_backlight_update_status(struct backlight_device *bd) +{ + struct dp_aux_backlight *bl = bl_get_data(bd); + u16 brightness = backlight_get_brightness(bd); + int ret = 0;
+ if (!backlight_is_blank(bd)) { + if (!bl->enabled) { + drm_edp_backlight_enable(bl->aux, &bl->info, brightness); + bl->enabled = true; + return 0; + } + ret = drm_edp_backlight_set_level(bl->aux, &bl->info, brightness); + } else { + if (bl->enabled) { + drm_edp_backlight_disable(bl->aux, &bl->info); + bl->enabled = false; + } + }
+ return ret; +}
+static const struct backlight_ops dp_aux_bl_ops = { + .update_status = dp_aux_backlight_update_status, +};
+/**
- drm_panel_dp_aux_backlight - create and use DP AUX backlight
- @panel: DRM panel
- @aux: The DP AUX channel to use
- Use this function to create and handle backlight if your panel
- supports backlight control over DP AUX channel using DPCD
- registers as per VESA's standard backlight control interface.
- When the panel is enabled backlight will be enabled after a
- successful call to &drm_panel_funcs.enable()
- When the panel is disabled backlight will be disabled before the
- call to &drm_panel_funcs.disable().
- A typical implementation for a panel driver supporting backlight
- control over DP AUX will call this function at probe time.
- Backlight will then be handled transparently without requiring
- any intervention from the driver.
- drm_panel_dp_aux_backlight() must be called after the call to
drm_panel_init().
- Return: 0 on success or a negative error code on failure.
- */
+int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux) +{ + struct dp_aux_backlight *bl; + struct backlight_properties props = { 0 }; + u16 current_level; + u8 current_mode; + u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE]; + int ret;
+ if (!panel || !panel->dev || !aux) + return -EINVAL;
+ ret = drm_dp_dpcd_read(aux, DP_EDP_DPCD_REV, edp_dpcd, + EDP_DISPLAY_CTL_CAP_SIZE);
This creates a cyclic dependency between drm_kms_helper-ko and drm.ko. drm_panel.c is in the latter, while drm_dp_dpcd_read() in drm_dp_helper.c is in the former. Please fix.
FYI, build DRM as modules and the error shows up during make module_install.
Best regards Thomas