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From 0c7fb448e0e0e47c2b3be64e438208682c6a5e61 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Mon, 9 Oct 2023 16:32:45 +0100
Subject: [PATCH] fbdev: Allow client to request a particular /dev/fbN node
Add a flag custom_fb_num to denote that the client has
requested a specific fbdev node number via node.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
drivers/video/fbdev/core/fbmem.c | 24 +++++++++++++++++-------
include/linux/fb.h | 2 ++
2 files changed, 19 insertions(+), 7 deletions(-)
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -52,6 +52,7 @@ static DEFINE_MUTEX(registration_lock);
struct fb_info *registered_fb[FB_MAX] __read_mostly;
int num_registered_fb __read_mostly;
+int min_dynamic_fb __read_mostly;
#define for_each_registered_fb(i) \
for (i = 0; i < FB_MAX; i++) \
if (!registered_fb[i]) {} else
@@ -1579,19 +1580,22 @@ static int do_register_framebuffer(struc
return -ENXIO;
num_registered_fb++;
- for (i = 0 ; i < FB_MAX; i++)
- if (!registered_fb[i])
- break;
- fb_info->node = i;
+ if (!fb_info->custom_fb_num || fb_info->node >= FB_MAX || registered_fb[fb_info->node]) {
+ for (i = min_dynamic_fb ; i < FB_MAX; i++)
+ if (!registered_fb[i])
+ break;
+ fb_info->node = i;
+ }
refcount_set(&fb_info->count, 1);
mutex_init(&fb_info->lock);
mutex_init(&fb_info->mm_lock);
fb_info->dev = device_create(fb_class, fb_info->device,
- MKDEV(FB_MAJOR, i), NULL, "fb%d", i);
+ MKDEV(FB_MAJOR, fb_info->node), NULL, "fb%d", fb_info->node);
if (IS_ERR(fb_info->dev)) {
/* Not fatal */
- printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));
+ printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n",
+ fb_info->node, PTR_ERR(fb_info->dev));
fb_info->dev = NULL;
} else
fb_init_device(fb_info);
@@ -1624,7 +1628,7 @@ static int do_register_framebuffer(struc
fb_var_to_videomode(&mode, &fb_info->var);
fb_add_videomode(&mode, &fb_info->modelist);
- registered_fb[i] = fb_info;
+ registered_fb[fb_info->node] = fb_info;
#ifdef CONFIG_GUMSTIX_AM200EPD
{
@@ -1719,6 +1723,12 @@ static int fb_aperture_acquire_for_platf
return ret;
}
+void fb_set_lowest_dynamic_fb(int min_fb_dev)
+{
+ min_dynamic_fb = min_fb_dev;
+}
+EXPORT_SYMBOL(fb_set_lowest_dynamic_fb);
+
/**
* register_framebuffer - registers a frame buffer device
* @fb_info: frame buffer info structure
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -512,6 +512,7 @@ struct fb_info {
} *apertures;
bool skip_vt_switch; /* no VT switch on suspend/resume required */
+ bool custom_fb_num; /* Use value in node as the preferred node number */
};
static inline struct apertures_struct *alloc_apertures(unsigned int max_num) {
@@ -614,6 +615,7 @@ extern ssize_t fb_sys_write(struct fb_in
size_t count, loff_t *ppos);
/* drivers/video/fbmem.c */
+extern void fb_set_lowest_dynamic_fb(int min_fb_dev);
extern int register_framebuffer(struct fb_info *fb_info);
extern void unregister_framebuffer(struct fb_info *fb_info);
extern int fb_prepare_logo(struct fb_info *fb_info, int rotate);
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