linux-kernel - [PATCH 2/3] fbcon: Add an option to disable fbcon in panic.

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Message-ID: <20240717090102.968152-3-jfalempe@redhat.com>
Date: Wed, 17 Jul 2024 10:48:40 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Helge Deller <deller@....de>,
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Javier Martinez Canillas <javierm@...hat.com>,
	Samuel Thibault <samuel.thibault@...-lyon.org>,
	Jocelyn Falempe <jfalempe@...hat.com>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	linux-fbdev@...r.kernel.org
Subject: [PATCH 2/3] fbcon: Add an option to disable fbcon in panic.

This is required to avoid conflict between DRM_PANIC, and fbcon. If
a drm device already handle panic with drm_panic, it should set
the skip_panic field in fb_info, so that fbcon will stay quiet, and
not overwrite the panic_screen.

Signed-off-by: Jocelyn Falempe <jfalempe@...hat.com>
---
 drivers/gpu/drm/drm_fb_helper.c  | 2 ++
 drivers/video/fbdev/core/fbcon.c | 7 ++++++-
 include/linux/fb.h               | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index e2e19f49342e..3662d664d8f9 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -40,6 +40,7 @@
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_panic.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 
@@ -524,6 +525,7 @@ struct fb_info *drm_fb_helper_alloc_info(struct drm_fb_helper *fb_helper)
 	fb_helper->info = info;
 	info->skip_vt_switch = true;
 
+	info->skip_panic = drm_panic_is_enabled(fb_helper->dev);
 	return info;
 
 err_release:
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 3f7333dca508..498d9c07df80 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -270,12 +270,17 @@ static int fbcon_get_rotate(struct fb_info *info)
 	return (ops) ? ops->rotate : 0;
 }
 
+static bool fbcon_skip_panic(struct fb_info *info)
+{
+	return (info->skip_panic && unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID));
+}
+
 static inline int fbcon_is_inactive(struct vc_data *vc, struct fb_info *info)
 {
 	struct fbcon_ops *ops = info->fbcon_par;
 
 	return (info->state != FBINFO_STATE_RUNNING ||
-		vc->vc_mode != KD_TEXT || ops->graphics);
+		vc->vc_mode != KD_TEXT || ops->graphics || fbcon_skip_panic(info));
 }
 
 static int get_color(struct vc_data *vc, struct fb_info *info,
diff --git a/include/linux/fb.h b/include/linux/fb.h
index db7d97b10964..865dad03e73e 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -510,6 +510,7 @@ struct fb_info {
 	void *par;
 
 	bool skip_vt_switch; /* no VT switch on suspend/resume required */
+	bool skip_panic; /* Do not write to the fb after a panic */
 };
 
 /* This will go away
-- 
2.45.2