linux/include/video/udlfb.h
Mikulas Patocka 68a958a915 udlfb: handle unplug properly
The udlfb driver maintained an open count and cleaned up itself when the
count reached zero. But the console is also counted in the reference count
- so, if the user unplugged the device, the open count would not drop to
zero and the driver stayed loaded with console attached. If the user
re-plugged the adapter, it would create a device /dev/fb1, show green
screen and the access to the console would be lost.

The framebuffer subsystem has reference counting on its own - in order to
fix the unplug bug, we rely the framebuffer reference counting. When the
user unplugs the adapter, we call unregister_framebuffer unconditionally.
unregister_framebuffer will unbind the console, wait until all users stop
using the framebuffer and then call the fb_destroy method. The fb_destroy
cleans up the USB driver.

This patch makes the following changes:
* Drop dlfb->kref and rely on implicit framebuffer reference counting
  instead.
* dlfb_usb_disconnect calls unregister_framebuffer, the rest of driver
  cleanup is done in the function dlfb_ops_destroy. dlfb_ops_destroy will
  be called by the framebuffer subsystem when no processes have the
  framebuffer open or mapped.
* We don't use workqueue during initialization, but initialize directly
  from dlfb_usb_probe. The workqueue could race with dlfb_usb_disconnect
  and this racing would produce various kinds of memory corruption.
* We use usb_get_dev and usb_put_dev to make sure that the USB subsystem
  doesn't free the device under us.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
cc: Dave Airlie <airlied@redhat.com>
Cc: Bernie Thompson <bernie@plugable.com>,
Cc: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
2018-10-08 12:57:34 +02:00

97 lines
2.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef UDLFB_H
#define UDLFB_H
/*
* TODO: Propose standard fb.h ioctl for reporting damage,
* using _IOWR() and one of the existing area structs from fb.h
* Consider these ioctls deprecated, but they're still used by the
* DisplayLink X server as yet - need both to be modified in tandem
* when new ioctl(s) are ready.
*/
#define DLFB_IOCTL_RETURN_EDID 0xAD
#define DLFB_IOCTL_REPORT_DAMAGE 0xAA
struct dloarea {
int x, y;
int w, h;
int x2, y2;
};
struct urb_node {
struct list_head entry;
struct dlfb_data *dlfb;
struct urb *urb;
};
struct urb_list {
struct list_head list;
spinlock_t lock;
struct semaphore limit_sem;
int available;
int count;
size_t size;
};
struct dlfb_data {
struct usb_device *udev;
struct fb_info *info;
struct urb_list urbs;
char *backing_buffer;
int fb_count;
bool virtualized; /* true when physical usb device not present */
atomic_t usb_active; /* 0 = update virtual buffer, but no usb traffic */
atomic_t lost_pixels; /* 1 = a render op failed. Need screen refresh */
char *edid; /* null until we read edid from hw or get from sysfs */
size_t edid_size;
int sku_pixel_limit;
int base16;
int base8;
u32 pseudo_palette[256];
int blank_mode; /*one of FB_BLANK_ */
struct fb_ops ops;
/* blit-only rendering path metrics, exposed through sysfs */
atomic_t bytes_rendered; /* raw pixel-bytes driver asked to render */
atomic_t bytes_identical; /* saved effort with backbuffer comparison */
atomic_t bytes_sent; /* to usb, after compression including overhead */
atomic_t cpu_kcycles_used; /* transpired during pixel processing */
struct fb_var_screeninfo current_mode;
struct list_head deferred_free;
};
#define NR_USB_REQUEST_I2C_SUB_IO 0x02
#define NR_USB_REQUEST_CHANNEL 0x12
/* -BULK_SIZE as per usb-skeleton. Can we get full page and avoid overhead? */
#define BULK_SIZE 512
#define MAX_TRANSFER (PAGE_SIZE*16 - BULK_SIZE)
#define WRITES_IN_FLIGHT (4)
#define MAX_VENDOR_DESCRIPTOR_SIZE 256
#define GET_URB_TIMEOUT HZ
#define FREE_URB_TIMEOUT (HZ*2)
#define BPP 2
#define MAX_CMD_PIXELS 255
#define RLX_HEADER_BYTES 7
#define MIN_RLX_PIX_BYTES 4
#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)
#define RLE_HEADER_BYTES 6
#define MIN_RLE_PIX_BYTES 3
#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)
#define RAW_HEADER_BYTES 6
#define MIN_RAW_PIX_BYTES 2
#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)
#define DL_DEFIO_WRITE_DELAY msecs_to_jiffies(HZ <= 300 ? 4 : 10) /* optimal value for 720p video */
#define DL_DEFIO_WRITE_DISABLE (HZ*60) /* "disable" with long delay */
/* remove these once align.h patch is taken into kernel */
#define DL_ALIGN_UP(x, a) ALIGN(x, a)
#define DL_ALIGN_DOWN(x, a) ALIGN_DOWN(x, a)
#endif