udlfb: Add module_param to allow forcing pixel_limit
Some user scenarios need to prioritize performance over
maxiumum resolution.
Also, some devices may have bad vendor descriptors, and
this allows the user to set a pixel limit that matches
their specific device to avoid blank screens on higher
resolution monitors.
700000 minimum for DL-115, 2360000 maximum for DL-195
Signed-off-by: Ben Collins <bcollins@ubuntu.com>
Signed-off-by: Bernie Thompson <bernie@plugable.com>
diff --git a/drivers/video/udlfb.c b/drivers/video/udlfb.c
index 4330cf4..86c8b25 100644
--- a/drivers/video/udlfb.c
+++ b/drivers/video/udlfb.c
@@ -72,6 +72,7 @@
static bool console = 1; /* Allow fbcon to open framebuffer */
static bool fb_defio = 1; /* Detect mmap writes using page faults */
static bool shadow = 1; /* Optionally disable shadow framebuffer */
+static int pixel_limit; /* Optionally force a pixel resolution limit */
/* dlfb keeps a list of urbs for efficient bulk transfers */
static void dlfb_urb_completion(struct urb *urb);
@@ -1616,6 +1617,14 @@
goto error;
}
+ if (pixel_limit) {
+ pr_warn("DL chip limit of %d overriden"
+ " by module param to %d\n",
+ dev->sku_pixel_limit, pixel_limit);
+ dev->sku_pixel_limit = pixel_limit;
+ }
+
+
if (!dlfb_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
retval = -ENOMEM;
pr_err("dlfb_alloc_urb_list failed\n");
@@ -1963,6 +1972,9 @@
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_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
+MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
+
MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
"Jaya Kumar <jayakumar.lkml@gmail.com>, "
"Bernie Thompson <bernie@plugable.com>");