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Date: Fri, 11 Apr 2014 14:28:28 -0600
From: Shuah Khan <shuah.kh@...sung.com>
To: Mauro Carvalho Chehab <m.chehab@...sung.com>,
One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
Greg KH <gregkh@...uxfoundation.org>
Cc: tj@...nel.org, rafael.j.wysocki@...el.com, linux@...ck-us.net,
toshi.kani@...com, linux-kernel@...r.kernel.org,
linux-media@...r.kernel.org, shuahkhan@...il.com,
Shuah Khan <shuah.kh@...sung.com>
Subject: Re: [RFC PATCH 0/2] managed token devres interfaces
Here is an example driver use-case for this token resource: This is not
polished, but should give an idea on this new token resource is intended
to be used:
- create token resources in em28xx_usb_probe() right before the required
modules are loaded. It creates tuner, video and audio tokens to use as a
large grain lock on tuner, video DMA engine, and audio DMA engine
respectively.
- lock video token in em28xx_init_usb_xfer()
- unlock in em28xx_uninit_usb_xfer()
- destroy token in em28xx_release_resources()
I did some hotplug testing with this:
dmesg | grep token
[ 771.613332] usb 8-1: devm_token_create(): created token:
tuner:8-1-0000:00:10.1-0
[ 771.613335] em2874 #0: devm_token_create() returned 0
[ 771.613340] usb 8-1: devm_token_create(): created token:
video:8-1-0000:00:10.1
[ 851.202931] usb 8-1: devm_token_release(): release token
[ 851.202936] usb 8-1: devm_token_release(): release token
[ 1775.052273] usb 8-2: devm_token_create(): created token:
tuner:8-2-0000:00:10.1-0
[ 1775.052276] em2874 #0: devm_token_create() returned 0
[ 1775.052285] usb 8-2: devm_token_create(): created token:
video:8-2-0000:00:10.1
shuah@...uin:~$ dmesg | grep token
[ 771.613332] usb 8-1: devm_token_create(): created token:
tuner:8-1-0000:00:10.1-0
[ 771.613335] em2874 #0: devm_token_create() returned 0
[ 771.613340] usb 8-1: devm_token_create(): created token:
video:8-1-0000:00:10.1
[ 851.202931] usb 8-1: devm_token_release(): release token
[ 851.202936] usb 8-1: devm_token_release(): release token
[ 1775.052273] usb 8-2: devm_token_create(): created token:
tuner:8-2-0000:00:10.1-0
[ 1775.052276] em2874 #0: devm_token_create() returned 0
[ 1775.052285] usb 8-2: devm_token_create(): created token:
video:8-2-0000:00:10.1
[ 1799.610007] usb 8-2: devm_token_release(): release token
[ 1799.610013] usb 8-2: devm_token_release(): release token
diff --git a/drivers/media/usb/em28xx/em28xx-cards.c
b/drivers/media/usb/em28xx/em28xx-cards.c
index 50aa5a5..3305250 100644
--- a/drivers/media/usb/em28xx/em28xx-cards.c
+++ b/drivers/media/usb/em28xx/em28xx-cards.c
@@ -2428,6 +2428,51 @@ static struct em28xx_hash_table em28xx_i2c_hash[] = {
};
/* NOTE: introduce a separate hash table for devices with 16 bit
eeproms */
+/* interfaces to create and destroy token resources */
+static int em28xx_create_token_resources(struct em28xx *dev)
+{
+ int rc = 0;
+
+ /* create token devres for tuner */
+ snprintf(dev->tuner_tkn_id, sizeof(dev->tuner_tkn_id),
+ "tuner:%s-%s-%d",
+ dev_name(&dev->udev->dev),
+ dev->udev->bus->bus_name,
+ dev->tuner_addr);
+
+ rc = devm_token_create(&dev->udev->dev, dev->tuner_tkn_id);
+ em28xx_info("devm_token_create() returned %d\n", rc);
+
+ if (dev->has_video || dev->board.has_dvb) {
+ snprintf(dev->video_tkn_id, sizeof(dev->video_tkn_id),
+ "video:%s-%s",
+ dev_name(&dev->udev->dev),
+ dev->udev->bus->bus_name);
+ rc = devm_token_create(&dev->udev->dev, dev->video_tkn_id);
+ }
+ if (dev->audio_mode.has_audio) {
+ snprintf(dev->audio_tkn_id, sizeof(dev->audio_tkn_id),
+ "audio:%s-%s",
+ dev_name(&dev->udev->dev),
+ dev->udev->bus->bus_name);
+ rc = devm_token_create(&dev->udev->dev, dev->audio_tkn_id);
+ }
+ return rc;
+}
+
+static int em28xx_destroy_token_resources(struct em28xx *dev)
+{
+ int rc = 0;
+
+ devm_token_destroy(&dev->udev->dev, dev->tuner_tkn_id);
+ if (dev->has_video || dev->board.has_dvb)
+ rc = devm_token_destroy(&dev->udev->dev, dev->video_tkn_id);
+ if (dev->audio_mode.has_audio)
+ rc = devm_token_destroy(&dev->udev->dev, dev->audio_tkn_id);
+
+ return rc;
+}
int em28xx_tuner_callback(void *ptr, int component, int command, int arg)
{
struct em28xx_i2c_bus *i2c_bus = ptr;
@@ -2949,6 +2994,10 @@ static void em28xx_release_resources(struct
em28xx *dev)
em28xx_i2c_unregister(dev, 1);
em28xx_i2c_unregister(dev, 0);
+ /* destroy token resources */
+ if (em28xx_destroy_token_resources(dev))
+ em28xx_info("Error destroying token resources\n");
+
usb_put_dev(dev->udev);
/* Mark device as unused */
@@ -3431,6 +3480,10 @@ static int em28xx_usb_probe(struct usb_interface
*interface,
kref_init(&dev->ref);
+ /* create token resources before requesting for modules */
+ if (em28xx_create_token_resources(dev))
+ em28xx_info("Error creating token resources\n");
+
request_modules(dev);
/* Should be the last thing to do, to avoid newer udev's to
diff --git a/drivers/media/usb/em28xx/em28xx-core.c
b/drivers/media/usb/em28xx/em28xx-core.c
index 523d7e9..8129a9c 100644
--- a/drivers/media/usb/em28xx/em28xx-core.c
+++ b/drivers/media/usb/em28xx/em28xx-core.c
@@ -824,6 +824,9 @@ void em28xx_uninit_usb_xfer(struct em28xx *dev, enum
em28xx_mode mode)
usb_bufs->num_bufs = 0;
em28xx_capture_start(dev, 0);
+
+ /* unlock token */
+ devm_token_unlock(&dev->udev->dev, dev->video_tkn_id);
}
EXPORT_SYMBOL_GPL(em28xx_uninit_usb_xfer);
@@ -993,6 +996,11 @@ int em28xx_init_usb_xfer(struct em28xx *dev, enum
em28xx_mode mode,
em28xx_isocdbg("em28xx: called em28xx_init_usb_xfer in mode %d\n",
mode);
+ /* lock token */
+ rc = devm_token_lock(&dev->udev->dev, dev->video_tkn_id);
+ if (rc)
+ return rc;
+
dev->usb_ctl.urb_data_copy = urb_data_copy;
if (mode == EM28XX_DIGITAL_MODE) {
diff --git a/drivers/media/usb/em28xx/em28xx.h
b/drivers/media/usb/em28xx/em28xx.h
index 2051fc9..b13ec6e 100644
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -34,6 +34,7 @@
#include <linux/mutex.h>
#include <linux/kref.h>
#include <linux/videodev2.h>
+#include <linux/token_devres.h>
#include <media/videobuf2-vmalloc.h>
#include <media/v4l2-device.h>
@@ -547,6 +548,11 @@ struct em28xx {
int devno; /* marks the number of this device */
enum em28xx_chip_id chip_id;
+ /* token resources */
+ char tuner_tkn_id[64]; /* tuner token id */
+ char video_tkn_id[64]; /* video dma engine token */
+ char audio_tkn_id[64]; /* audio dma engine token id */
+
unsigned int is_em25xx:1; /* em25xx/em276x/7x/8x family
bridge */
unsigned char disconnected:1; /* device has been diconnected */
unsigned int has_video:1;
thanks
-- Shuah
--
Shuah Khan
Senior Linux Kernel Developer - Open Source Group
Samsung Research America(Silicon Valley)
shuah.kh@...sung.com | (970) 672-0658
--
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