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uterm: monitor: mark DRM-fbdev devices as such

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Most DRM drivers also provide a legacy fbdev device so fbcon can pick it
up (and more importantly, we get kernel panics on it). However, as an
application developer, I don't want to use two devices which drive the
same physical hardware.

This marks all such DRM fbdev devices as FBDEV_DRM so kmscon doesn't pick
them up automatically.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
This commit is contained in:
David Herrmann 2012-09-21 14:25:10 +02:00
parent ed969b99a8
commit 02ddaaeb9f
2 changed files with 58 additions and 1 deletions
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1
src/uterm.h
View File

@ -373,6 +373,7 @@ enum uterm_monitor_event_type {
enum uterm_monitor_dev_type {
UTERM_MONITOR_DRM,
UTERM_MONITOR_FBDEV,
UTERM_MONITOR_FBDEV_DRM,
UTERM_MONITOR_INPUT,
};

58
src/uterm_monitor.c
View File

@ -34,9 +34,12 @@
#include <errno.h>
#include <fcntl.h>
#include <libudev.h>
#include <linux/fb.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include "log.h"
#include "shl_dlist.h"
#include "uterm.h"
@ -389,6 +392,56 @@ static int get_fb_id(struct udev_device *dev)
return devnum;
}
/*
* Nearly all DRM drivers do also create fbdev nodes which refer to the same
* hardware as the DRM devices. So we shouldn't advertise these fbdev nodes as
* real devices. Otherwise, the user might use these and the DRM devices
* simultaneously, thinking that they deal with two different hardware devices.
*
* We also report that it is a drm-device if we actually cannot verify that it
* is not some DRM device.
*/
static bool is_drm_fbdev(const char *node)
{
int fd, ret, len;
struct fb_fix_screeninfo finfo;
bool res = true;
fd = open(node, O_RDWR | O_CLOEXEC);
if (fd < 0) {
log_warning("cannot open fbdev node %s for drm-device verification (%d): %m",
node, errno);
return true;
}
ret = ioctl(fd, FBIOGET_FSCREENINFO, &finfo);
if (ret) {
log_warning("cannot retrieve finfo from fbdev node %s for drm-device verification (%d): %m",
node, errno);
goto err_close;
}
/* TODO: we really need some reliable flag here that tells us that we
* are dealing with a DRM device indirectly. Checking for "drmfb" suffix
* seems fine, but that may be just luck.
* If this turns out to not work reliably, we can also fall back to
* checking whether the parent udev device node does also provide a DRM
* device. */
len = strlen(finfo.id);
if (len > 5 && !strcmp(&finfo.id[len - 5], "drmfb"))
goto err_close;
if (!strcmp(finfo.id, "nouveaufb"))
goto err_close;
if (!strcmp(finfo.id, "psbfb"))
goto err_close;
res = false;
err_close:
close(fd);
return res;
}
static void monitor_udev_add(struct uterm_monitor *mon,
struct udev_device *dev)
{
@ -447,7 +500,10 @@ static void monitor_udev_add(struct uterm_monitor *mon,
return;
}
sname = udev_device_get_property_value(dev, "ID_SEAT");
type = UTERM_MONITOR_FBDEV;
if (is_drm_fbdev(node))
type = UTERM_MONITOR_FBDEV_DRM;
else
type = UTERM_MONITOR_FBDEV;
} else if (!strcmp(subs, "input")) {
sysname = udev_device_get_sysname(dev);
if (!sysname || strncmp(sysname, "event", 5)) {