[PATCH v2 1/4] video: fb: Make fbcon dmi quirks usuable for drm drivers too

[Hans de Goede <j.w.r.degoede@gmail.com>]

Some x86 clamshell design devices use portrait tablet LCD panels and a
display engine which cannot (transparently) rotate in hardware, so we
need to rotate things in software / let user space deal with this.

The fbcon code has a set of DMI based quirks to automatically detect
such tablet LCD panels and rotate the fbcon to compensate.

The plan was for userspace (e.g. a Wayland compositor) to simply read
/sys/class/graphics/fbcon/rotate and apply the rotation from there to
the LCD panel to compensate.

However this will not work when an external monitor gets plugged in,
since with fbcon rotation is not per output, so the fbcon quirk code
disables the rotation when an external monitor is present.

Using /sys/class/graphics/fbcon/rotate will not help in that case
since it will indicate no rotation is in use. So instead we are going
to need a drm connecter property for this.

This commit is a preparation patch for adding the drm-connecter
property, by making the fbcon quirk code generally usable so that
the drm code can use it to check for rotation quirks.

Note this commit re-uses the FB_CMDLINE Kconfig option for selecting
if the quirk code should be build, since that is already selected by
both the drm and fbcon code.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
-Rebased on 4.14-rc1
---
 drivers/video/fbdev/core/Makefile                  |  6 +++---
 .../core/{fbcon_dmi_quirks.c => fb_dmi_quirks.c}   | 15 +++++++++------
 drivers/video/fbdev/core/fbcon.c                   | 22 ++++++++++++++--------
 drivers/video/fbdev/core/fbcon.h                   |  6 ------
 include/linux/fb.h                                 |  6 ++++++
 5 files changed, 32 insertions(+), 23 deletions(-)
 rename drivers/video/fbdev/core/{fbcon_dmi_quirks.c => fb_dmi_quirks.c} (91%)

diff --git a/drivers/video/fbdev/core/Makefile b/drivers/video/fbdev/core/Makefile
index 73493bbd7a15..06caf037a822 100644
--- a/drivers/video/fbdev/core/Makefile
+++ b/drivers/video/fbdev/core/Makefile
@@ -1,4 +1,7 @@
 obj-$(CONFIG_FB_CMDLINE)          += fb_cmdline.o
+ifeq ($(CONFIG_DMI),y)
+obj-$(CONFIG_FB_CMDLINE)          += fb_dmi_quirks.o
+endif
 obj-$(CONFIG_FB_NOTIFY)           += fb_notify.o
 obj-$(CONFIG_FB)                  += fb.o
 fb-y                              := fbmem.o fbmon.o fbcmap.o fbsysfs.o \
@@ -14,9 +17,6 @@ ifeq ($(CONFIG_FRAMEBUFFER_CONSOLE_ROTATION),y)
 fb-y				  += fbcon_rotate.o fbcon_cw.o fbcon_ud.o \
 				     fbcon_ccw.o
 endif
-ifeq ($(CONFIG_DMI),y)
-fb-y				  += fbcon_dmi_quirks.o
-endif
 endif
 fb-objs                           := $(fb-y)
 
diff --git a/drivers/video/fbdev/core/fbcon_dmi_quirks.c b/drivers/video/fbdev/core/fb_dmi_quirks.c
similarity index 91%
rename from drivers/video/fbdev/core/fbcon_dmi_quirks.c
rename to drivers/video/fbdev/core/fb_dmi_quirks.c
index 6904e47d1e51..d5fdf3245f83 100644
--- a/drivers/video/fbdev/core/fbcon_dmi_quirks.c
+++ b/drivers/video/fbdev/core/fb_dmi_quirks.c
@@ -1,5 +1,5 @@
 /*
- *  fbcon_dmi_quirks.c -- DMI based quirk detection for fbcon
+ *  fb_dmi_quirks.c -- DMI based LCD panel rotation quirk detection
  *
  *	Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
  *
@@ -11,7 +11,6 @@
 #include <linux/dmi.h>
 #include <linux/fb.h>
 #include <linux/kernel.h>
-#include "fbcon.h"
 
 /*
  * Some x86 clamshell design devices use portrait tablet screens and a display
@@ -112,7 +111,11 @@ static const struct dmi_system_id rotate_data[] = {
 	{}
 };
 
-int fbcon_platform_get_rotate(struct fb_info *info)
+/*
+ * Note this function returns the rotation necessary to put the display
+ * the right way up, or -1 if there is no quirk.
+ */
+int fb_get_panel_rotate_quirk(int width, int height)
 {
 	const struct dmi_system_id *match;
 	const struct fbcon_dmi_rotate_data *data;
@@ -124,8 +127,7 @@ int fbcon_platform_get_rotate(struct fb_info *info)
 	     match = dmi_first_match(match + 1)) {
 		data = match->driver_data;
 
-		if (data->width != info->var.xres ||
-		    data->height != info->var.yres)
+		if (data->width != width || data->height != height)
 			continue;
 
 		if (!data->bios_dates)
@@ -141,5 +143,6 @@ int fbcon_platform_get_rotate(struct fb_info *info)
 		}
 	}
 
-	return FB_ROTATE_UR;
+	return -1;
 }
+EXPORT_SYMBOL_GPL(fb_get_panel_rotate_quirk);
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 04612f938bab..2e17ea02c295 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -963,10 +963,13 @@ static const char *fbcon_startup(void)
 	ops->cur_rotate = -1;
 	ops->cur_blink_jiffies = HZ / 5;
 	info->fbcon_par = ops;
-	if (initial_rotation != -1)
-		p->con_rotate = initial_rotation;
-	else
-		p->con_rotate = fbcon_platform_get_rotate(info);
+	p->con_rotate = initial_rotation;
+	if (p->con_rotate = -1)
+		p->con_rotate = fb_get_panel_rotate_quirk(info->var.xres,
+							  info->var.yres);
+	if (p->con_rotate = -1)
+		p->con_rotate = FB_ROTATE_UR;
+
 	set_blitting_type(vc, info);
 
 	if (info->fix.type != FB_TYPE_TEXT) {
@@ -1103,10 +1106,13 @@ static void fbcon_init(struct vc_data *vc, int init)
 
 	ops = info->fbcon_par;
 	ops->cur_blink_jiffies = msecs_to_jiffies(vc->vc_cur_blink_ms);
-	if (initial_rotation != -1)
-		p->con_rotate = initial_rotation;
-	else
-		p->con_rotate = fbcon_platform_get_rotate(info);
+	p->con_rotate = initial_rotation;
+	if (p->con_rotate = -1)
+		p->con_rotate = fb_get_panel_rotate_quirk(info->var.xres,
+							  info->var.yres);
+	if (p->con_rotate = -1)
+		p->con_rotate = FB_ROTATE_UR;
+
 	set_blitting_type(vc, info);
 
 	cols = vc->vc_cols;
diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
index 18f3ac144237..3746828356ed 100644
--- a/drivers/video/fbdev/core/fbcon.h
+++ b/drivers/video/fbdev/core/fbcon.h
@@ -261,10 +261,4 @@ extern void fbcon_set_rotate(struct fbcon_ops *ops);
 #define fbcon_set_rotate(x) do {} while(0)
 #endif /* CONFIG_FRAMEBUFFER_CONSOLE_ROTATION */
 
-#ifdef CONFIG_DMI
-int fbcon_platform_get_rotate(struct fb_info *info);
-#else
-#define fbcon_platform_get_rotate(i) FB_ROTATE_UR
-#endif /* CONFIG_DMI */
-
 #endif /* _VIDEO_FBCON_H */
diff --git a/include/linux/fb.h b/include/linux/fb.h
index f4386b0ccf40..7527965c5b53 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -814,6 +814,12 @@ extern int fb_find_mode(struct fb_var_screeninfo *var,
 			const struct fb_videomode *default_mode,
 			unsigned int default_bpp);
 
+#ifdef CONFIG_DMI
+int fb_get_panel_rotate_quirk(int width, int height);
+#else
+#define fb_get_panel_rotate_quirk(width, height) (-1)
+#endif /* CONFIG_DMI */
+
 /* Convenience logging macros */
 #define fb_err(fb_info, fmt, ...)					\
 	pr_err("fb%d: " fmt, (fb_info)->node, ##__VA_ARGS__)
-- 
2.14.2