diff options
| -rw-r--r-- | Documentation/fb/udlfb.txt | 5 | ||||
| -rw-r--r-- | drivers/video/udlfb.c | 10 |
2 files changed, 13 insertions, 2 deletions
diff --git a/Documentation/fb/udlfb.txt b/Documentation/fb/udlfb.txt index 7fdde2a02a27..473ceed9e4eb 100644 --- a/Documentation/fb/udlfb.txt +++ b/Documentation/fb/udlfb.txt @@ -105,6 +105,11 @@ console Allow fbcon to attach to udlfb provided framebuffers. This the first framebuffer it finds, which isn't usually what the user wants in the case of USB displays. +shadow Allocate a 2nd framebuffer to shadow what's currently across + the USB bus in device memory. If any pixels are unchanged, + do not transmit. Spends host memory to save USB transfers. + Enabled by default. Only disable on very low memory systems. + Sysfs Attributes ================ diff --git a/drivers/video/udlfb.c b/drivers/video/udlfb.c index 37498abcd917..2341b275e815 100644 --- a/drivers/video/udlfb.c +++ b/drivers/video/udlfb.c @@ -62,6 +62,7 @@ MODULE_DEVICE_TABLE(usb, id_table); /* module options */ static int console; /* Optionally allow fbcon to consume first framebuffer */ static int fb_defio; /* Optionally enable experimental fb_defio mmap support */ +static int shadow = 1; /* Optionally disable shadow framebuffer */ /* dlfb keeps a list of urbs for efficient bulk transfers */ static void dlfb_urb_completion(struct urb *urb); @@ -1148,7 +1149,7 @@ static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info) int new_len; unsigned char *old_fb = info->screen_base; unsigned char *new_fb; - unsigned char *new_back; + unsigned char *new_back = 0; pr_warn("Reallocating framebuffer. Addresses will change!\n"); @@ -1180,7 +1181,8 @@ static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info) * But with imperfect damage info we may send pixels over USB * that were, in fact, unchanged - wasting limited USB bandwidth */ - new_back = vzalloc(new_len); + if (shadow) + new_back = vzalloc(new_len); if (!new_back) pr_info("No shadow/backing buffer allocated\n"); else { @@ -1593,6 +1595,7 @@ static int dlfb_usb_probe(struct usb_interface *interface, usbdev->descriptor.bcdDevice, dev); pr_info("console enable=%d\n", console); pr_info("fb_defio enable=%d\n", fb_defio); + pr_info("shadow enable=%d\n", shadow); dev->sku_pixel_limit = 2048 * 1152; /* default to maximum */ @@ -1950,6 +1953,9 @@ MODULE_PARM_DESC(console, "Allow fbcon to consume first framebuffer found"); module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP); MODULE_PARM_DESC(fb_defio, "Enable fb_defio mmap support. *Experimental*"); +module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP); +MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf"); + MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, " "Jaya Kumar <jayakumar.lkml@gmail.com>, " "Bernie Thompson <bernie@plugable.com>"); |