| Message ID | 37219a840909012132l6c04af65hddecd2d52e196bcb@mail.gmail.com (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
Am Mittwoch, den 02.09.2009, 00:32 -0400 schrieb Michael Krufky: > Over the course of the past year, a number of developers have > expressed a need for giving the bridge drivers better control over > dvb_frontend operations. Specifically, there is a need for the bridge > driver to receive a DVB frontend IOCTL and have the opportunity to > allow or deny the IOCTL to proceed, as resources permit. > > For instance, in the case of a hybrid device, only the bridge driver > knows whether the analog functionality is presently being used. If > the driver is currently in analog mode, serving video frames, the > driver will have a chance to deny the DVB frontend ioctl request > before dvb-core passes the request on to the frontend driver, > potentially damaging the analog video stream already in progress. > > In some cases, the bridge driver might have to perform a setup > operation to use a feature specific to the device. For instance, the > bridge device may be in a low powered state - this new capability > allows the driver to wake up before passing the command on to the > frontend driver. This new feature will allow LinuxTV developers to > finally get working on actual power management support within the > v4l/dvb subsystem, without the fear of breaking devices with hybrid > analog / digital functionality. > > In other cases, there may be situations in which multiple RF > connectors are available to the tuner, but only the bridge driver will > be aware of this, as this type of thing is specific to the device's > hardware implementation. As there are many tuners capable of multiple > RF spigots, not all devices actually employ this feature - only the > bridge driver knows what implementations support such features, and > how to enable / disable them. > > The possibilities are endless. I actually did all the heavy lifting > involved in this a few months ago, but haven't had a moment to write > up this RFC until now. > > The change to dvb-core that allows this new functionality is posted to > my development repository on kernellabs.com. I have also included an > example of how this can be used on a digital tuner board with multiple > RF inputs. The multiple RF input switching is already supported in > today's code, but I promised Mauro that I would present a better > method of doing this before the upcoming merge window. For your > review and comments, please take a look at the topmost changesets, > starting with "create a standard method for dvb adapter drivers to > override frontend ioctls": > > http://kernellabs.com/hg/~mkrufky/fe_ioctl_override > > For those that would prefer not to open up a web browser, here are the > core changes (apologies if whitespace becomes broken): > > --- a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c Tue Jun 16 > 16:08:17 2009 -0400 > +++ b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c Sat May 23 > 17:00:59 2009 -0400 > @@ -1594,7 +1594,18 @@ > struct dvb_device *dvbdev = file->private_data; > struct dvb_frontend *fe = dvbdev->priv; > struct dvb_frontend_private *fepriv = fe->frontend_priv; > - int err = -EOPNOTSUPP; > + int cb_err, err = -EOPNOTSUPP; > + > + if (fe->dvb->fe_ioctl_override) { > + cb_err = fe->dvb->fe_ioctl_override(fe, cmd, parg, > + DVB_FE_IOCTL_PRE); > + if (cb_err < 0) > + return cb_err; > + if (cb_err > 0) > + return 0; > + /* fe_ioctl_override returning 0 allows > + * dvb-core to continue handling the ioctl */ > + } > > switch (cmd) { > case FE_GET_INFO: { > @@ -1858,6 +1869,13 @@ > err = 0; > break; > }; > + > + if (fe->dvb->fe_ioctl_override) { > + cb_err = fe->dvb->fe_ioctl_override(fe, cmd, parg, > + DVB_FE_IOCTL_POST); > + if (cb_err < 0) > + return cb_err; > + } > > return err; > } > --- a/linux/drivers/media/dvb/dvb-core/dvbdev.h Tue Jun 16 16:08:17 2009 -0400 > +++ b/linux/drivers/media/dvb/dvb-core/dvbdev.h Sat May 23 17:00:59 2009 -0400 > @@ -51,6 +51,8 @@ > module_param_array(adapter_nr, short, NULL, 0444); \ > MODULE_PARM_DESC(adapter_nr, "DVB adapter numbers") > > +struct dvb_frontend; > + > struct dvb_adapter { > int num; > struct list_head list_head; > @@ -66,6 +68,32 @@ > int mfe_shared; /* indicates mutually exclusive frontends */ > struct dvb_device *mfe_dvbdev; /* frontend device in use */ > struct mutex mfe_lock; /* access lock for thread creation */ > + > + /* Allow the adapter/bridge driver to perform an action before and/or > + * after the core handles an ioctl: > + * > + * DVB_FE_IOCTL_PRE indicates that the ioctl has not yet been handled. > + * DVB_FE_IOCTL_POST indicates that the ioctl has been handled. > + * > + * When DVB_FE_IOCTL_PRE is passed to the callback as the stage arg: > + * > + * return 0 to allow dvb-core to handle the ioctl. > + * return a positive int to prevent dvb-core from handling the ioctl, > + * and exit without error. > + * return a negative int to prevent dvb-core from handling the ioctl, > + * and return that value as an error. > + * > + * When DVB_FE_IOCTL_POST is passed to the callback as the stage arg: > + * > + * return 0 to allow the dvb_frontend ioctl handler to exit normally. > + * return a negative int to cause the dvb_frontend ioctl handler to > + * return that value as an error. > + */ > +#define DVB_FE_IOCTL_PRE 0 > +#define DVB_FE_IOCTL_POST 1 > + int (*fe_ioctl_override)(struct dvb_frontend *fe, > + unsigned int cmd, void *parg, > + unsigned int stage); > }; > > > > > > As you can see from the changeset, this allows the bridge to assert > control both before and after the frontend driver itself handles the > operation. Depending on the value returned by the bridge driver, > dvb-core can exit with error, proceed unchanged, or exit without > error. > > In order to allow some drivers to use the new feature, I had to make a > small change to videobuf-dvb: > > --- a/linux/drivers/media/video/videobuf-dvb.c Tue Jun 16 16:08:17 2009 -0400 > +++ b/linux/drivers/media/video/videobuf-dvb.c Sat May 23 17:00:59 2009 -0400 > @@ -144,7 +144,9 @@ > struct device *device, > char *adapter_name, > short *adapter_nr, > - int mfe_shared) > + int mfe_shared, > + int (*fe_ioctl_override)(struct dvb_frontend *, > + unsigned int, void *, unsigned int)) > { > int result; > > @@ -159,6 +161,7 @@ > } > fe->adapter.priv = adapter_priv; > fe->adapter.mfe_shared = mfe_shared; > + fe->adapter.fe_ioctl_override = fe_ioctl_override; > > return result; > } > @@ -258,7 +261,9 @@ > void *adapter_priv, > struct device *device, > short *adapter_nr, > - int mfe_shared) > + int mfe_shared, > + int (*fe_ioctl_override)(struct dvb_frontend *, > + unsigned int, void *, unsigned int)) > { > struct list_head *list, *q; > struct videobuf_dvb_frontend *fe; > @@ -272,7 +277,7 @@ > > /* Bring up the adapter */ > res = videobuf_dvb_register_adapter(f, module, adapter_priv, device, > - fe->dvb.name, adapter_nr, mfe_shared); > + fe->dvb.name, adapter_nr, mfe_shared, fe_ioctl_override); > if (res < 0) { > printk(KERN_WARNING "videobuf_dvb_register_adapter failed (errno = > %d)\n", res); > return res; > --- a/linux/include/media/videobuf-dvb.h Tue Jun 16 16:08:17 2009 -0400 > +++ b/linux/include/media/videobuf-dvb.h Sat May 23 17:00:59 2009 -0400 > @@ -42,7 +42,9 @@ > void *adapter_priv, > struct device *device, > short *adapter_nr, > - int mfe_shared); > + int mfe_shared, > + int (*fe_ioctl_override)(struct dvb_frontend *, > + unsigned int, void *, unsigned int)); > > void videobuf_dvb_unregister_bus(struct videobuf_dvb_frontends *f); > > --- a/linux/drivers/media/video/cx23885/cx23885-dvb.c Tue Jun 16 > 16:08:17 2009 -0400 > +++ b/linux/drivers/media/video/cx23885/cx23885-dvb.c Sat May 23 > 17:00:59 2009 -0400 > @@ -856,7 +856,7 @@ > > /* register everything */ > ret = videobuf_dvb_register_bus(&port->frontends, THIS_MODULE, port, > - &dev->pci->dev, adapter_nr, 0); > + &dev->pci->dev, adapter_nr, 0, NULL); > > /* init CI & MAC */ > switch (dev->board) { > --- a/linux/drivers/media/video/cx88/cx88-dvb.c Tue Jun 16 16:08:17 2009 -0400 > +++ b/linux/drivers/media/video/cx88/cx88-dvb.c Sat May 23 17:00:59 2009 -0400 > @@ -1180,7 +1180,7 @@ > > /* register everything */ > return videobuf_dvb_register_bus(&dev->frontends, THIS_MODULE, dev, > - &dev->pci->dev, adapter_nr, mfe_shared); > + &dev->pci->dev, adapter_nr, mfe_shared, NULL); > > frontend_detach: > core->gate_ctrl = NULL; > --- a/linux/drivers/media/video/saa7134/saa7134-dvb.c Tue Jun 16 > 16:08:17 2009 -0400 > +++ b/linux/drivers/media/video/saa7134/saa7134-dvb.c Sat May 23 > 17:00:59 2009 -0400 > @@ -1509,7 +1509,7 @@ > > /* register everything else */ > ret = videobuf_dvb_register_bus(&dev->frontends, THIS_MODULE, dev, > - &dev->pci->dev, adapter_nr, 0); > + &dev->pci->dev, adapter_nr, 0, NULL); > > /* this sequence is necessary to make the tda1004x load its firmware > * and to enter analog mode of hybrid boards > > > > > Finally, the actual implementation of this new feature in the cx23885 > driver for the sake of RF input switching: > > --- a/linux/drivers/media/video/cx23885/cx23885-dvb.c Sat May 23 > 17:00:59 2009 -0400 > +++ b/linux/drivers/media/video/cx23885/cx23885-dvb.c Fri May 08 > 21:39:24 2009 -0400 > @@ -484,9 +484,33 @@ > } > break; > } > - return (port->set_frontend_save) ? > - port->set_frontend_save(fe, param) : -ENODEV; > + return 0; > } > + > +static int cx23885_dvb_fe_ioctl_override(struct dvb_frontend *fe, > + unsigned int cmd, void *parg, > + unsigned int stage) > +{ > + int err = 0; > + > + switch (stage) { > + case DVB_FE_IOCTL_PRE: > + > + switch (cmd) { > + case FE_SET_FRONTEND: > + err = cx23885_dvb_set_frontend(fe, > + (struct dvb_frontend_parameters *) parg); > + break; > + } > + break; > + > + case DVB_FE_IOCTL_POST: > + /* no post-ioctl handling required */ > + break; > + } > + return err; > +}; > + > > static int dvb_register(struct cx23885_tsport *port) > { > @@ -527,12 +551,6 @@ > 0x60, &dev->i2c_bus[1].i2c_adap, > &hauppauge_hvr127x_config); > } > - > - /* FIXME: temporary hack */ > - /* define bridge override to set_frontend */ > - port->set_frontend_save = fe0->dvb.frontend->ops.set_frontend; > - fe0->dvb.frontend->ops.set_frontend = cx23885_dvb_set_frontend; > - > break; > case CX23885_BOARD_HAUPPAUGE_HVR1255: > i2c_bus = &dev->i2c_bus[0]; > @@ -856,7 +874,8 @@ > > /* register everything */ > ret = videobuf_dvb_register_bus(&port->frontends, THIS_MODULE, port, > - &dev->pci->dev, adapter_nr, 0, NULL); > + &dev->pci->dev, adapter_nr, 0, > + cx23885_dvb_fe_ioctl_override); > > /* init CI & MAC */ > switch (dev->board) { > --- a/linux/drivers/media/video/cx23885/cx23885.h Sat May 23 17:00:59 2009 -0400 > +++ b/linux/drivers/media/video/cx23885/cx23885.h Fri May 08 21:39:24 2009 -0400 > @@ -289,10 +289,6 @@ > /* Allow a single tsport to have multiple frontends */ > u32 num_frontends; > void *port_priv; > - > - /* FIXME: temporary hack */ > - int (*set_frontend_save) (struct dvb_frontend *, > - struct dvb_frontend_parameters *); > }; > > struct cx23885_dev { > > > > > Again, the above changeset simply removes the old RF input path > switching hack, and implements the feature using the new frontend > ioctl override method instead. This is a much cleaner and more more > robust way to handle this, which actually opening doors for other > drivers to handle similar problems in a much more efficient manner. > > Please voice your comments about this particular change and any of its > implications in this thread. If all goes well, I'd like to merge this > into the master repository in time for the next merge window. Once > this is in the master branch, I can start working on removing other > similar hacks from other drivers in our tree, in favor of this better > method. > > Cheers, > > Michael Krufky > -- I'm all for it. Cheers, Hermann -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 09/02/2009 07:32 AM, Michael Krufky wrote: > Over the course of the past year, a number of developers have > expressed a need for giving the bridge drivers better control over > dvb_frontend operations. Specifically, there is a need for the bridge > driver to receive a DVB frontend IOCTL and have the opportunity to > allow or deny the IOCTL to proceed, as resources permit. > > For instance, in the case of a hybrid device, only the bridge driver > knows whether the analog functionality is presently being used. If > the driver is currently in analog mode, serving video frames, the > driver will have a chance to deny the DVB frontend ioctl request > before dvb-core passes the request on to the frontend driver, > potentially damaging the analog video stream already in progress. > > In some cases, the bridge driver might have to perform a setup > operation to use a feature specific to the device. For instance, the > bridge device may be in a low powered state - this new capability > allows the driver to wake up before passing the command on to the > frontend driver. This new feature will allow LinuxTV developers to > finally get working on actual power management support within the > v4l/dvb subsystem, without the fear of breaking devices with hybrid > analog / digital functionality. > > In other cases, there may be situations in which multiple RF > connectors are available to the tuner, but only the bridge driver will > be aware of this, as this type of thing is specific to the device's > hardware implementation. As there are many tuners capable of multiple > RF spigots, not all devices actually employ this feature - only the > bridge driver knows what implementations support such features, and > how to enable / disable them. > > The possibilities are endless. I actually did all the heavy lifting > involved in this a few months ago, but haven't had a moment to write > up this RFC until now. > > The change to dvb-core that allows this new functionality is posted to > my development repository on kernellabs.com. I have also included an > example of how this can be used on a digital tuner board with multiple > RF inputs. The multiple RF input switching is already supported in > today's code, but I promised Mauro that I would present a better > method of doing this before the upcoming merge window. For your > review and comments, please take a look at the topmost changesets, > starting with "create a standard method for dvb adapter drivers to > override frontend ioctls": > > http://kernellabs.com/hg/~mkrufky/fe_ioctl_override Idea looks very good! I tested one DVB USB device need blocking IOCTLs when demod and tuner are power save and didn't saw functionality problems. However, it was a little bit hard to add callback to DVB USB driver. Could that callback be added to the struct dvb_usb_adapter_properties for simplify things? I have feeling that this callback will be useful most DVb USB devices - setting GPIOs and clock settings for power save. Name fe_ioctl_override sounds like whole IOCTL will be replaced with new one which is not true. Still, I don't know which could be better name. Antti
On Fri, Sep 4, 2009 at 11:11 AM, Antti Palosaari<crope@iki.fi> wrote: > On 09/02/2009 07:32 AM, Michael Krufky wrote: >> >> Over the course of the past year, a number of developers have >> expressed a need for giving the bridge drivers better control over >> dvb_frontend operations. Â Specifically, there is a need for the bridge >> driver to receive a DVB frontend IOCTL and have the opportunity to >> allow or deny the IOCTL to proceed, as resources permit. >> >> For instance, in the case of a hybrid device, only the bridge driver >> knows whether the analog functionality is presently being used. Â If >> the driver is currently in analog mode, serving video frames, the >> driver will have a chance to deny the DVB frontend ioctl request >> before dvb-core passes the request on to the frontend driver, >> potentially damaging the analog video stream already in progress. >> >> In some cases, the bridge driver might have to perform a setup >> operation to use a feature specific to the device. Â For instance, the >> bridge device may be in a low powered state - this new capability >> allows the driver to wake up before passing the command on to the >> frontend driver. Â This new feature will allow LinuxTV developers to >> finally get working on actual power management support within the >> v4l/dvb subsystem, without the fear of breaking devices with hybrid >> analog / digital functionality. >> >> In other cases, there may be situations in which multiple RF >> connectors are available to the tuner, but only the bridge driver will >> be aware of this, as this type of thing is specific to the device's >> hardware implementation. Â As there are many tuners capable of multiple >> RF spigots, not all devices actually employ this feature - only the >> bridge driver knows what implementations support such features, and >> how to enable / disable them. >> >> The possibilities are endless. Â I actually did all the heavy lifting >> involved in this a few months ago, but haven't had a moment to write >> up this RFC until now. >> >> The change to dvb-core that allows this new functionality is posted to >> my development repository on kernellabs.com. Â I have also included an >> example of how this can be used on a digital tuner board with multiple >> RF inputs. Â The multiple RF input switching is already supported in >> today's code, but I promised Mauro that I would present a better >> method of doing this before the upcoming merge window. Â For your >> review and comments, please take a look at the topmost changesets, >> starting with "create a standard method for dvb adapter drivers to >> override frontend ioctls": >> >> http://kernellabs.com/hg/~mkrufky/fe_ioctl_override > > Idea looks very good! I tested one DVB USB device need blocking IOCTLs when > demod and tuner are power save and didn't saw functionality problems. > > However, it was a little bit hard to add callback to DVB USB driver. Could > that callback be added to the struct dvb_usb_adapter_properties for simplify > things? I have feeling that this callback will be useful most DVb USB > devices - setting GPIOs and clock settings for power save. > > Name fe_ioctl_override sounds like whole IOCTL will be replaced with new one > which is not true. Still, I don't know which could be better name. Thank you for the feedback, Antti. Yes, I can add a generic mechanism into the DVB USB device framework to enable this functionality there. I'll take care of that after we merge the initial core changes, or maybe I will have time to do that over the next week. You're right, this feature will certainly be useful in the dvb-usb framework, as well as many others. As far as the name fe_ioctl_override, this does apply to the entire IOCTL, but currently only being used for SET_FRONTEND. As more needs arise, the possibilities of this feature will become more prominent. This is not a "replacement" for the IOCTL per se. As the comments in dvbdev.h explain, depending on the return value of the bridge callback, this will determine whether or not the previous default IOCTL handling should be allowed to continue, or whether the bridge's override returns back to userspace itself. So, if configured a certain way, this feature CAN be used to replace dvb-core's IOCTL handling, but in most cases it will simply allow the bridge to do pre-processing and post-processing of a given IOCTL. As fe_ioctl_override is actually most descriptive of the process going on, I'd like to keep that name as-is. Cheers, Mike -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Sep 4, 2009 at 11:28 AM, Michael Krufky<mkrufky@kernellabs.com> wrote: > On Fri, Sep 4, 2009 at 11:11 AM, Antti Palosaari<crope@iki.fi> wrote: >> On 09/02/2009 07:32 AM, Michael Krufky wrote: >>> >>> Over the course of the past year, a number of developers have >>> expressed a need for giving the bridge drivers better control over >>> dvb_frontend operations. Â Specifically, there is a need for the bridge >>> driver to receive a DVB frontend IOCTL and have the opportunity to >>> allow or deny the IOCTL to proceed, as resources permit. >>> >>> For instance, in the case of a hybrid device, only the bridge driver >>> knows whether the analog functionality is presently being used. Â If >>> the driver is currently in analog mode, serving video frames, the >>> driver will have a chance to deny the DVB frontend ioctl request >>> before dvb-core passes the request on to the frontend driver, >>> potentially damaging the analog video stream already in progress. >>> >>> In some cases, the bridge driver might have to perform a setup >>> operation to use a feature specific to the device. Â For instance, the >>> bridge device may be in a low powered state - this new capability >>> allows the driver to wake up before passing the command on to the >>> frontend driver. Â This new feature will allow LinuxTV developers to >>> finally get working on actual power management support within the >>> v4l/dvb subsystem, without the fear of breaking devices with hybrid >>> analog / digital functionality. >>> >>> In other cases, there may be situations in which multiple RF >>> connectors are available to the tuner, but only the bridge driver will >>> be aware of this, as this type of thing is specific to the device's >>> hardware implementation. Â As there are many tuners capable of multiple >>> RF spigots, not all devices actually employ this feature - only the >>> bridge driver knows what implementations support such features, and >>> how to enable / disable them. >>> >>> The possibilities are endless. Â I actually did all the heavy lifting >>> involved in this a few months ago, but haven't had a moment to write >>> up this RFC until now. >>> >>> The change to dvb-core that allows this new functionality is posted to >>> my development repository on kernellabs.com. Â I have also included an >>> example of how this can be used on a digital tuner board with multiple >>> RF inputs. Â The multiple RF input switching is already supported in >>> today's code, but I promised Mauro that I would present a better >>> method of doing this before the upcoming merge window. Â For your >>> review and comments, please take a look at the topmost changesets, >>> starting with "create a standard method for dvb adapter drivers to >>> override frontend ioctls": >>> >>> http://kernellabs.com/hg/~mkrufky/fe_ioctl_override >> >> Idea looks very good! I tested one DVB USB device need blocking IOCTLs when >> demod and tuner are power save and didn't saw functionality problems. >> >> However, it was a little bit hard to add callback to DVB USB driver. Could >> that callback be added to the struct dvb_usb_adapter_properties for simplify >> things? I have feeling that this callback will be useful most DVb USB >> devices - setting GPIOs and clock settings for power save. >> >> Name fe_ioctl_override sounds like whole IOCTL will be replaced with new one >> which is not true. Still, I don't know which could be better name. > > Thank you for the feedback, Antti. > > Yes, I can add a generic mechanism into the DVB USB device framework > to enable this functionality there. Â I'll take care of that after we > merge the initial core changes, or maybe I will have time to do that > over the next week. Â You're right, this feature will certainly be > useful in the dvb-usb framework, as well as many others. > > As far as the name fe_ioctl_override, this does apply to the entire > IOCTL, but currently only being used for SET_FRONTEND. Â As more needs > arise, the possibilities of this feature will become more prominent. > > This is not a "replacement" for the IOCTL per se. Â As the comments in > dvbdev.h explain, depending on the return value of the bridge > callback, this will determine whether or not the previous default > IOCTL handling should be allowed to continue, or whether the bridge's > override returns back to userspace itself. Â So, if configured a > certain way, this feature CAN be used to replace dvb-core's IOCTL > handling, but in most cases it will simply allow the bridge to do > pre-processing and post-processing of a given IOCTL. > > As fe_ioctl_override is actually most descriptive of the process going > on, I'd like to keep that name as-is. Antti, I pushed the change to let dvb-usb drivers specify an fe_ioctl_override callback within the dvb_usb_adapter_properties structure. Please check the repository for the latest changesets. I plan to ask Mauro to merge this tree at some point over this next week -- If anybody else has comments, please chime in :-) Regards, Mike -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> I pushed the change to let dvb-usb drivers specify an > fe_ioctl_override callback within the dvb_usb_adapter_properties > structure. Please check the repository for the latest changesets. > > I plan to ask Mauro to merge this tree at some point over this next > week -- If anybody else has comments, please chime in :-) I'm good with this RFC, it adds feature that enable the bridge (opt-in) to make intelligent decisions on behalf of complex products related to resource usage and tuning, something we've needed for a while. Acked-By: Steven Toth <stoth@kernellabs.com>
--- a/linux/drivers/media/dvb/dvb-core/dvbdev.h Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/drivers/media/dvb/dvb-core/dvbdev.h Sat May 23 17:00:59 2009 -0400 @@ -51,6 +51,8 @@ module_param_array(adapter_nr, short, NULL, 0444); \ MODULE_PARM_DESC(adapter_nr, "DVB adapter numbers") +struct dvb_frontend; + struct dvb_adapter { int num; struct list_head list_head; @@ -66,6 +68,32 @@ int mfe_shared; /* indicates mutually exclusive frontends */ struct dvb_device *mfe_dvbdev; /* frontend device in use */ struct mutex mfe_lock; /* access lock for thread creation */ + + /* Allow the adapter/bridge driver to perform an action before and/or + * after the core handles an ioctl: + * + * DVB_FE_IOCTL_PRE indicates that the ioctl has not yet been handled. + * DVB_FE_IOCTL_POST indicates that the ioctl has been handled. + * + * When DVB_FE_IOCTL_PRE is passed to the callback as the stage arg: + * + * return 0 to allow dvb-core to handle the ioctl. + * return a positive int to prevent dvb-core from handling the ioctl, + * and exit without error. + * return a negative int to prevent dvb-core from handling the ioctl, + * and return that value as an error. + * + * When DVB_FE_IOCTL_POST is passed to the callback as the stage arg: + * + * return 0 to allow the dvb_frontend ioctl handler to exit normally. + * return a negative int to cause the dvb_frontend ioctl handler to + * return that value as an error. + */ +#define DVB_FE_IOCTL_PRE 0 +#define DVB_FE_IOCTL_POST 1 + int (*fe_ioctl_override)(struct dvb_frontend *fe, + unsigned int cmd, void *parg, + unsigned int stage); }; As you can see from the changeset, this allows the bridge to assert control both before and after the frontend driver itself handles the operation. Â Depending on the value returned by the bridge driver, dvb-core can exit with error, proceed unchanged, or exit without error. In order to allow some drivers to use the new feature, I had to make a small change to videobuf-dvb: --- a/linux/drivers/media/video/videobuf-dvb.c Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/drivers/media/video/videobuf-dvb.c Sat May 23 17:00:59 2009 -0400 @@ -144,7 +144,9 @@ struct device *device, char *adapter_name, short *adapter_nr, - int mfe_shared) + int mfe_shared, + int (*fe_ioctl_override)(struct dvb_frontend *, + unsigned int, void *, unsigned int)) { int result; @@ -159,6 +161,7 @@ } fe->adapter.priv = adapter_priv; fe->adapter.mfe_shared = mfe_shared; + fe->adapter.fe_ioctl_override = fe_ioctl_override; return result; } @@ -258,7 +261,9 @@ void *adapter_priv, struct device *device, short *adapter_nr, - int mfe_shared) + int mfe_shared, + int (*fe_ioctl_override)(struct dvb_frontend *, + unsigned int, void *, unsigned int)) { struct list_head *list, *q; struct videobuf_dvb_frontend *fe; @@ -272,7 +277,7 @@ /* Bring up the adapter */ res = videobuf_dvb_register_adapter(f, module, adapter_priv, device, - fe->dvb.name, adapter_nr, mfe_shared); + fe->dvb.name, adapter_nr, mfe_shared, fe_ioctl_override); if (res < 0) { printk(KERN_WARNING "videobuf_dvb_register_adapter failed (errno = %d)\n", res); return res; --- a/linux/include/media/videobuf-dvb.h Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/include/media/videobuf-dvb.h Sat May 23 17:00:59 2009 -0400 @@ -42,7 +42,9 @@ void *adapter_priv, struct device *device, short *adapter_nr, - int mfe_shared); + int mfe_shared, + int (*fe_ioctl_override)(struct dvb_frontend *, + unsigned int, void *, unsigned int)); void videobuf_dvb_unregister_bus(struct videobuf_dvb_frontends *f); --- a/linux/drivers/media/video/cx23885/cx23885-dvb.c Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/drivers/media/video/cx23885/cx23885-dvb.c Sat May 23 17:00:59 2009 -0400 @@ -856,7 +856,7 @@ /* register everything */ ret = videobuf_dvb_register_bus(&port->frontends, THIS_MODULE, port, - &dev->pci->dev, adapter_nr, 0); + &dev->pci->dev, adapter_nr, 0, NULL); /* init CI & MAC */ switch (dev->board) { --- a/linux/drivers/media/video/cx88/cx88-dvb.c Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/drivers/media/video/cx88/cx88-dvb.c Sat May 23 17:00:59 2009 -0400 @@ -1180,7 +1180,7 @@ /* register everything */ return videobuf_dvb_register_bus(&dev->frontends, THIS_MODULE, dev, - &dev->pci->dev, adapter_nr, mfe_shared); + &dev->pci->dev, adapter_nr, mfe_shared, NULL); frontend_detach: core->gate_ctrl = NULL; --- a/linux/drivers/media/video/saa7134/saa7134-dvb.c Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/drivers/media/video/saa7134/saa7134-dvb.c Sat May 23 17:00:59 2009 -0400 @@ -1509,7 +1509,7 @@ /* register everything else */ ret = videobuf_dvb_register_bus(&dev->frontends, THIS_MODULE, dev, - &dev->pci->dev, adapter_nr, 0); + &dev->pci->dev, adapter_nr, 0, NULL); /* this sequence is necessary to make the tda1004x load its firmware * and to enter analog mode of hybrid boards Finally, the actual implementation of this new feature in the cx23885 driver for the sake of RF input switching: --- a/linux/drivers/media/video/cx23885/cx23885-dvb.c Sat May 23 17:00:59 2009 -0400 +++ b/linux/drivers/media/video/cx23885/cx23885-dvb.c Fri May 08 21:39:24 2009 -0400 @@ -484,9 +484,33 @@ } break; } - return (port->set_frontend_save) ? - port->set_frontend_save(fe, param) : -ENODEV; + return 0; } + +static int cx23885_dvb_fe_ioctl_override(struct dvb_frontend *fe, + unsigned int cmd, void *parg, + unsigned int stage) +{ + int err = 0; + + switch (stage) { + case DVB_FE_IOCTL_PRE: + + switch (cmd) { + case FE_SET_FRONTEND: + err = cx23885_dvb_set_frontend(fe, + (struct dvb_frontend_parameters *) parg); + break; + } + break; + + case DVB_FE_IOCTL_POST: + /* no post-ioctl handling required */ + break; + } + return err; +}; + static int dvb_register(struct cx23885_tsport *port) { @@ -527,12 +551,6 @@ 0x60, &dev->i2c_bus[1].i2c_adap, &hauppauge_hvr127x_config); } - - /* FIXME: temporary hack */ - /* define bridge override to set_frontend */ - port->set_frontend_save = fe0->dvb.frontend->ops.set_frontend; - fe0->dvb.frontend->ops.set_frontend = cx23885_dvb_set_frontend; - break; case CX23885_BOARD_HAUPPAUGE_HVR1255: i2c_bus = &dev->i2c_bus[0]; @@ -856,7 +874,8 @@ /* register everything */ ret = videobuf_dvb_register_bus(&port->frontends, THIS_MODULE, port, - &dev->pci->dev, adapter_nr, 0, NULL); + &dev->pci->dev, adapter_nr, 0, + cx23885_dvb_fe_ioctl_override); /* init CI & MAC */ switch (dev->board) { --- a/linux/drivers/media/video/cx23885/cx23885.h Sat May 23 17:00:59 2009 -0400 +++ b/linux/drivers/media/video/cx23885/cx23885.h Fri May 08 21:39:24 2009 -0400 @@ -289,10 +289,6 @@ /* Allow a single tsport to have multiple frontends */ u32 num_frontends; void *port_priv; - - /* FIXME: temporary hack */ - int (*set_frontend_save) (struct dvb_frontend *, - struct dvb_frontend_parameters *); }; struct cx23885_dev {
Over the course of the past year, a number of developers have expressed a need for giving the bridge drivers better control over dvb_frontend operations. Â Specifically, there is a need for the bridge driver to receive a DVB frontend IOCTL and have the opportunity to allow or deny the IOCTL to proceed, as resources permit. For instance, in the case of a hybrid device, only the bridge driver knows whether the analog functionality is presently being used. Â If the driver is currently in analog mode, serving video frames, the driver will have a chance to deny the DVB frontend ioctl request before dvb-core passes the request on to the frontend driver, potentially damaging the analog video stream already in progress. In some cases, the bridge driver might have to perform a setup operation to use a feature specific to the device. Â For instance, the bridge device may be in a low powered state - this new capability allows the driver to wake up before passing the command on to the frontend driver. Â This new feature will allow LinuxTV developers to finally get working on actual power management support within the v4l/dvb subsystem, without the fear of breaking devices with hybrid analog / digital functionality. In other cases, there may be situations in which multiple RF connectors are available to the tuner, but only the bridge driver will be aware of this, as this type of thing is specific to the device's hardware implementation. Â As there are many tuners capable of multiple RF spigots, not all devices actually employ this feature - only the bridge driver knows what implementations support such features, and how to enable / disable them. The possibilities are endless. Â I actually did all the heavy lifting involved in this a few months ago, but haven't had a moment to write up this RFC until now. The change to dvb-core that allows this new functionality is posted to my development repository on kernellabs.com. Â I have also included an example of how this can be used on a digital tuner board with multiple RF inputs. Â The multiple RF input switching is already supported in today's code, but I promised Mauro that I would present a better method of doing this before the upcoming merge window. Â For your review and comments, please take a look at the topmost changesets, starting with "create a standard method for dvb adapter drivers to override frontend ioctls": http://kernellabs.com/hg/~mkrufky/fe_ioctl_override For those that would prefer not to open up a web browser, here are the core changes (apologies if whitespace becomes broken): --- a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c Tue Jun 16 16:08:17 2009 -0400 +++ b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c Sat May 23 17:00:59 2009 -0400 @@ -1594,7 +1594,18 @@ struct dvb_device *dvbdev = file->private_data; struct dvb_frontend *fe = dvbdev->priv; struct dvb_frontend_private *fepriv = fe->frontend_priv; - int err = -EOPNOTSUPP; + int cb_err, err = -EOPNOTSUPP; + + if (fe->dvb->fe_ioctl_override) { + cb_err = fe->dvb->fe_ioctl_override(fe, cmd, parg, + DVB_FE_IOCTL_PRE); + if (cb_err < 0) + return cb_err; + if (cb_err > 0) + return 0; + /* fe_ioctl_override returning 0 allows + * dvb-core to continue handling the ioctl */ + } switch (cmd) { case FE_GET_INFO: { @@ -1858,6 +1869,13 @@ err = 0; break; }; + + if (fe->dvb->fe_ioctl_override) { + cb_err = fe->dvb->fe_ioctl_override(fe, cmd, parg, + DVB_FE_IOCTL_POST); + if (cb_err < 0) + return cb_err; + } return err; } Again, the above changeset simply removes the old RF input path switching hack, and implements the feature using the new frontend ioctl override method instead. Â This is a much cleaner and more more robust way to handle this, which actually opening doors for other drivers to handle similar problems in a much more efficient manner. Please voice your comments about this particular change and any of its implications in this thread. Â If all goes well, I'd like to merge this into the master repository in time for the next merge window. Â Once this is in the master branch, I can start working on removing other similar hacks from other drivers in our tree, in favor of this better method. Cheers, Michael Krufky -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html