linux-kernel - [PATCH v2 30/38] fbdev/smscufx: Detect registered fb

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Message-ID: <20230612141352.29939-31-tzimmermann@suse.de>
Date:   Mon, 12 Jun 2023 16:08:08 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     daniel@...ll.ch, javierm@...hat.com, sam@...nborg.org,
        deller@....de, geert+renesas@...der.be, lee@...nel.org,
        daniel.thompson@...aro.org, jingoohan1@...il.com,
        dan.carpenter@...aro.org, michael.j.ruhl@...el.com
Cc:     linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-sh@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Steve Glendinning <steve.glendinning@...well.net>
Subject: [PATCH v2 30/38] fbdev/smscufx: Detect registered fb_info from refcount

Detect registered instances of fb_info by reading the reference
counter from struct fb_info.read. Avoids looking at the dev field
and prepares fbdev for making struct fb_info.dev optional.

Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
Cc: Steve Glendinning <steve.glendinning@...well.net>
Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
---
 drivers/video/fbdev/smscufx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/smscufx.c b/drivers/video/fbdev/smscufx.c
index 17cec62cc65db..adb2b1fe8383c 100644
--- a/drivers/video/fbdev/smscufx.c
+++ b/drivers/video/fbdev/smscufx.c
@@ -1496,7 +1496,7 @@ static int ufx_setup_modes(struct ufx_data *dev, struct fb_info *info,
 	u8 *edid;
 	int i, result = 0, tries = 3;
 
-	if (info->dev) /* only use mutex if info has been registered */
+	if (refcount_read(&info->count)) /* only use mutex if info has been registered */
 		mutex_lock(&info->lock);
 
 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
@@ -1610,7 +1610,7 @@ static int ufx_setup_modes(struct ufx_data *dev, struct fb_info *info,
 	if (edid && (dev->edid != edid))
 		kfree(edid);
 
-	if (info->dev)
+	if (refcount_read(&info->count))
 		mutex_unlock(&info->lock);
 
 	return result;
-- 
2.41.0