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dm: stdio: Allow lazy probing of video devices

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At present all video devices are probed on start-up. It would be better to
probe a device only when it is needed. This can happen if it is referenced
in the stdout environment variable, for example.

Add support for this by searching for a suitable device when needed, probing
it, and finding the stdio device it creates.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Simon Glass 2016-10-05 20:42:16 -06:00 committed by Bin Meng
parent 1df9127628
commit d8441ea27e
1 changed files with 83 additions and 4 deletions
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87
common/stdio.c
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@ -121,19 +121,87 @@ struct list_head* stdio_get_list(void)
return &(devs.list);
}
#ifdef CONFIG_DM_VIDEO
/**
* stdio_probe_device() - Find a device which provides the given stdio device
*
* This looks for a device of the given uclass which provides a particular
* stdio device. It is currently really only useful for UCLASS_VIDEO.
*
* Ultimately we want to be able to probe a device by its stdio name. At
* present devices register in their probe function (for video devices this
* is done in vidconsole_post_probe()) and we don't know what name they will
* use until they do so.
* TODO(sjg@chromium.org): We should be able to determine the name before
* probing, and probe the required device.
*
* @name: stdio device name (e.g. "vidconsole")
* id: Uclass ID of device to look for (e.g. UCLASS_VIDEO)
* @sdevp: Returns stdout device, if found, else NULL
* @return 0 if found, -ENOENT if no device found with that name, other -ve
* on other error
*/
static int stdio_probe_device(const char *name, enum uclass_id id,
struct stdio_dev **sdevp)
{
struct stdio_dev *sdev;
struct udevice *dev;
int seq, ret;
*sdevp = NULL;
seq = trailing_strtoln(name, NULL);
if (seq == -1)
ret = uclass_first_device_err(id, &dev);
else
ret = uclass_get_device_by_seq(id, seq, &dev);
if (ret) {
debug("No %s device for seq %d (%s)\n", uclass_get_name(id),
seq, name);
return ret;
}
/* The device should be be the last one registered */
sdev = list_empty(&devs.list) ? NULL :
list_last_entry(&devs.list, struct stdio_dev, list);
if (!sdev || strcmp(sdev->name, name)) {
debug("Device '%s' did not register with stdio as '%s'\n",
dev->name, name);
return -ENOENT;
}
*sdevp = sdev;
return 0;
}
#endif
struct stdio_dev* stdio_get_by_name(const char *name)
{
struct list_head *pos;
struct stdio_dev *dev;
struct stdio_dev *sdev;
if(!name)
return NULL;
list_for_each(pos, &(devs.list)) {
dev = list_entry(pos, struct stdio_dev, list);
if(strcmp(dev->name, name) == 0)
return dev;
sdev = list_entry(pos, struct stdio_dev, list);
if (strcmp(sdev->name, name) == 0)
return sdev;
}
#ifdef CONFIG_DM_VIDEO
/*
* We did not find a suitable stdio device. If there is a video
* driver with a name starting with 'vidconsole', we can try probing
* that in the hope that it will produce the required stdio device.
*
* This function is sometimes called with the entire value of
* 'stdout', which may include a list of devices separate by commas.
* Obviously this is not going to work, so we ignore that case. The
* call path in that case is console_init_r() -> search_device() ->
* stdio_get_by_name().
*/
if (!strncmp(name, "vidconsole", 10) && !strchr(name, ',') &&
!stdio_probe_device(name, UCLASS_VIDEO, &sdev))
return sdev;
#endif
return NULL;
}
@ -282,6 +350,16 @@ int stdio_add_devices(void)
#endif
#endif
#ifdef CONFIG_DM_VIDEO
/*
* If the console setting is not in environment variables then
* console_init_r() will not be calling iomux_doenv() (which calls
* search_device()). So we will not dynamically add devices by
* calling stdio_probe_device().
*
* So just probe all video devices now so that whichever one is
* required will be available.
*/
#ifndef CONFIG_SYS_CONSOLE_IS_IN_ENV
struct udevice *vdev;
# ifndef CONFIG_DM_KEYBOARD
int ret;
@ -293,6 +371,7 @@ int stdio_add_devices(void)
;
if (ret)
printf("%s: Video device failed (ret=%d)\n", __func__, ret);
#endif /* !CONFIG_SYS_CONSOLE_IS_IN_ENV */
#else
# if defined(CONFIG_LCD)
drv_lcd_init ();