linux-kernel - [PATCH v2] drm/fb-helper: pass physical dimensions to fbdev

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Message-Id: <1501697571-16823-1-git-send-email-david@lechnology.com>
Date:   Wed,  2 Aug 2017 13:12:51 -0500
From:   David Lechner <david@...hnology.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     David Lechner <david@...hnology.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org
Subject: [PATCH v2] drm/fb-helper: pass physical dimensions to fbdev

The fbdev subsystem has a place for physical dimensions (width and height
in mm) that is readable by userspace. Since DRM also knows these
dimensions, pass this information to the fbdev device.

Signed-off-by: David Lechner <david@...hnology.com>
---

v1 changes (from RFC):
* Use loop to get info from first connected connector instead of just the
  first connector.

v2 changes:
* Update width in height in drm_setup_crtcs() also to handle hotplug events.


As mentioned in the comments below, drm_setup_crtcs() can't set these values
during init because the data structure hasn't been allocated yet, so we end up
doing the same thing in two different places.


 drivers/gpu/drm/drm_fb_helper.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index b2a01d1..7813b86 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1884,6 +1884,7 @@ void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helpe
 			    uint32_t fb_width, uint32_t fb_height)
 {
 	struct drm_framebuffer *fb = fb_helper->fb;
+	int i;
 
 	info->pseudo_palette = fb_helper->pseudo_palette;
 	info->var.xres_virtual = fb->width;
@@ -1896,6 +1897,18 @@ void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helpe
 	info->var.height = -1;
 	info->var.width = -1;
 
+	drm_fb_helper_for_each_connector(fb_helper, i) {
+		struct drm_connector *connector =
+			fb_helper->connector_info[i]->connector;
+
+		/* use the first connected connector for the physical dimensions */
+		if (connector->status == connector_status_connected) {
+			info->var.height = connector->display_info.width_mm;
+			info->var.width = connector->display_info.height_mm;
+			break;
+		}
+	}
+
 	switch (fb->format->depth) {
 	case 8:
 		info->var.red.offset = 0;
@@ -2355,6 +2368,7 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper,
 	struct drm_display_mode **modes;
 	struct drm_fb_offset *offsets;
 	bool *enabled;
+	bool var_updated = false;
 	int i;
 
 	DRM_DEBUG_KMS("\n");
@@ -2429,6 +2443,23 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper,
 			modeset->fb = fb_helper->fb;
 			modeset->x = offset->x;
 			modeset->y = offset->y;
+
+			/*
+			 * During init, drm_setup_crtcs() is called before the
+			 * fbdev is allocated, so this only affects hotplug
+			 * events.
+			 * Only the info from the first connected connector is
+			 * used.
+			 */
+			if (!var_updated && fb_helper->fbdev &&
+			    connector->status == connector_status_connected) {
+				struct fb_var_screeninfo *var =
+							&fb_helper->fbdev->var;
+
+				var->width = connector->display_info.width_mm;
+				var->height = connector->display_info.height_mm;
+				var_updated = true;
+			}
 		}
 	}
 out:
-- 
2.7.4