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@xxxxxxxxxxxxxx> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx> --- 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 -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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