Re: [Resubmit: PATCH-V2] Introducing ti-media directory

Re: [Resubmit: PATCH-V2] Introducing ti-media directory

[Laurent Pinchart]

On Friday 19 March 2010 10:35:50 hvaibhav@ti.com wrote:
> From: Vaibhav Hiremath <hvaibhav@ti.com>
> 
> Looking towards the number of files which are cluttering in media/video/
> directory, it is required to introduce seperate working
> directory for TI devices.

You should then move the omap24xxcam driver as well.

> Again the IP's are being re-used across the devices which makes it very
> difficuilt to re-use the driver code. For example, DM6446 and AM3517 both
> uses exactly same VPFE/CCDC IP, but the driver is encapsulated under
> DAVINCI which makes it impossible to re-use.

I'm not too sure to like the ti-media name. It will soon get quite crowded, 
and name collisions might occur (look at the linux-omap-camera tree and the 
ISP driver in there for instance). Isn't there an internal name to refer to 
both the DM6446 and AM3517 that could be used ?

> Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>

-- 
Regards,

Laurent Pinchart

RE: [Resubmit: PATCH-V2] Introducing ti-media directory

[Hiremath, Vaibhav]

> -----Original Message-----
> From: Laurent Pinchart [mailto:laurent.pinchart@ideasonboard.com]
> Sent: Tuesday, March 23, 2010 5:11 PM
> To: davinci-linux-open-source@linux.davincidsp.com
> Cc: Hiremath, Vaibhav; linux-media@vger.kernel.org
> Subject: Re: [Resubmit: PATCH-V2] Introducing ti-media directory
> 
> On Friday 19 March 2010 10:35:50 hvaibhav@ti.com wrote:
> > From: Vaibhav Hiremath <hvaibhav@ti.com>
> >
> > Looking towards the number of files which are cluttering in media/video/
> > directory, it is required to introduce seperate working
> > directory for TI devices.
> 
> You should then move the omap24xxcam driver as well.
[Hiremath, Vaibhav] I wanted to move this file to ti-media directory, but left it only because it is based on V4L2-Int framework (legacy).

> 
> > Again the IP's are being re-used across the devices which makes it very
> > difficuilt to re-use the driver code. For example, DM6446 and AM3517 both
> > uses exactly same VPFE/CCDC IP, but the driver is encapsulated under
> > DAVINCI which makes it impossible to re-use.
> 
> I'm not too sure to like the ti-media name. It will soon get quite crowded,
> and name collisions might occur (look at the linux-omap-camera tree and the
> ISP driver in there for instance). Isn't there an internal name to refer to
> both the DM6446 and AM3517 that could be used ?
[Hiremath, Vaibhav] Laurent,

ti-media directory is top level directory where we are putting all TI devices drivers. So having said that, we should worrying about what goes inside this directory.
For me ISP is more generic, if you compare davinci and OMAP. 

Frankly, there are various naming convention we do have from device to device, even if the IP's are being reused. For example, the internal name for OMAP is ISP but Davinci refers it as a VPSS.

Thanks,
Vaibhav

> 
> > Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
> 
> --
> Regards,
> 
> Laurent Pinchart

RE: [Resubmit: PATCH-V2] Introducing ti-media directory

[Karicheri, Muralidharan]

Laurent,

>>
>> I'm not too sure to like the ti-media name. It will soon get quite
>crowded,
>> and name collisions might occur (look at the linux-omap-camera tree and
>the
>> ISP driver in there for instance). Isn't there an internal name to refer
>to
>> both the DM6446 and AM3517 that could be used ?
>[Hiremath, Vaibhav] Laurent,
>
>ti-media directory is top level directory where we are putting all TI
>devices drivers. So having said that, we should worrying about what goes
>inside this directory.
>For me ISP is more generic, if you compare davinci and OMAP.
>
>Frankly, there are various naming convention we do have from device to
>device, even if the IP's are being reused. For example, the internal name
>for OMAP is ISP but Davinci refers it as a VPSS.
>

Could you explain what name space issue you are referring to in linux-omap-camera since I am not quite familiar with that tree?

Myself and Vaibhav had discussed this in the past and ti-media is the generic name that we could agree on. On DM SoCs (DM6446, DM355, DM365) I expect ti-media to be the home for all vpfe and vpbe driver files. Since we had a case of common IP across OMAP and DMxxx SoCs, we want to place all OMAP and DMxxx video driver files in a common directory so that sharing
the drivers across the SoCs will be easy. We could discuss and agree on another name if need be. Any suggestions?

>Thanks,
>Vaibhav
>
>>
>> > Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
>>
>> --
>> Regards,
>>
>> Laurent Pinchart
>_______________________________________________
>Davinci-linux-open-source mailing list
>Davinci-linux-open-source@linux.davincidsp.com
>http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source

Re: [Resubmit: PATCH-V2] Introducing ti-media directory

[Laurent Pinchart]

Hi Murali,

On Tuesday 23 March 2010 18:52:44 Karicheri, Muralidharan wrote:
> Laurent,
> 
> > > I'm not too sure to like the ti-media name. It will soon get quite
> > > crowded, and name collisions might occur (look at the linux-omap-camera
> > > tree and the ISP driver in there for instance). Isn't there an internal
> > > name to refer to both the DM6446 and AM3517 that could be used ?
> >
> > [Hiremath, Vaibhav] Laurent,
> >
> > ti-media directory is top level directory where we are putting all TI
> > devices drivers. So having said that, we should worrying about what goes
> > inside this directory.
> > For me ISP is more generic, if you compare davinci and OMAP.
> >
> > Frankly, there are various naming convention we do have from device to
> > device, even if the IP's are being reused. For example, the internal name
> > for OMAP is ISP but Davinci refers it as a VPSS.
> 
> Could you explain what name space issue you are referring to in
> linux-omap-camera since I am not quite familiar with that tree?

The linux-omap-camera tree contains a driver for the OMAP3 ISP. Basically, 
most source files start with the "isp" prefix and are stored in 
drivers/media/video/isp/.

ISP is quite a generic name, and other vendors will probably develop an ISP at 
some point (if not already done), so there's already a potential name conflict 
today.

Using a dedicated directory in drivers/media/video for TI-specific cores is 
definitely a good idea (assuming the same IP cores won't be used by other 
vendors in the future).

My concern is that, if we move the ISP driver in drivers/media/video/ti-media, 
the directory will soon get quite crowded. If a new TI processor comes up with 
a totally incompatible ISP, we will get a name conflict in 
drivers/media/video/ti-media. I was thinking about either replacing the "isp" 
prefix with "omap3isp" (or similar), or moving the driver to 
drivers/media/video/ti-media/omap3isp, but that will impede code sharing code 
between the Davinci and OMAP processor families. That's where my uncertainty 
comes from.

> Myself and Vaibhav had discussed this in the past and ti-media is the
> generic name that we could agree on. On DM SoCs (DM6446, DM355, DM365) I
> expect ti-media to be the home for all vpfe and vpbe driver files. Since
> we had a case of common IP across OMAP and DMxxx SoCs, we want to place
> all OMAP and DMxxx video driver files in a common directory so that
> sharing the drivers across the SoCs will be easy. We could discuss and
> agree on another name if need be. Any suggestions?

It's not the name ti-media that I don't agree on, it's just that this will 
move the problem one step further in the directory hierarchy without actually 
solving it :-)

Is it guaranteed today that no TI processors with new generation video blocks 
will reuse the names ISP, VPFE and VPBE ? The OMAP3 datasheet refers to VPFE 
and VPBE, but luckily those blocks are further divided into subblocks, and the 
driver doesn't refer to the VPFE and VPBE directly.

-- 
Regards,

Laurent Pinchart

Re: [Resubmit: PATCH-V2] Introducing ti-media directory

[Mauro Carvalho Chehab]

Laurent Pinchart wrote:
> Hi Murali,
> 
> On Tuesday 23 March 2010 18:52:44 Karicheri, Muralidharan wrote:
>> Laurent,
>>
>>>> I'm not too sure to like the ti-media name. It will soon get quite
>>>> crowded, and name collisions might occur (look at the linux-omap-camera
>>>> tree and the ISP driver in there for instance). Isn't there an internal
>>>> name to refer to both the DM6446 and AM3517 that could be used ?
>>> [Hiremath, Vaibhav] Laurent,
>>>
>>> ti-media directory is top level directory where we are putting all TI
>>> devices drivers. So having said that, we should worrying about what goes
>>> inside this directory.
>>> For me ISP is more generic, if you compare davinci and OMAP.
>>>
>>> Frankly, there are various naming convention we do have from device to
>>> device, even if the IP's are being reused. For example, the internal name
>>> for OMAP is ISP but Davinci refers it as a VPSS.
>> Could you explain what name space issue you are referring to in
>> linux-omap-camera since I am not quite familiar with that tree?
> 
> The linux-omap-camera tree contains a driver for the OMAP3 ISP. Basically, 
> most source files start with the "isp" prefix and are stored in 
> drivers/media/video/isp/.
> 
> ISP is quite a generic name, and other vendors will probably develop an ISP at 
> some point (if not already done), so there's already a potential name conflict 
> today.
> 
> Using a dedicated directory in drivers/media/video for TI-specific cores is 
> definitely a good idea (assuming the same IP cores won't be used by other 
> vendors in the future).
> 
> My concern is that, if we move the ISP driver in drivers/media/video/ti-media, 
> the directory will soon get quite crowded. If a new TI processor comes up with 
> a totally incompatible ISP, we will get a name conflict in 
> drivers/media/video/ti-media. I was thinking about either replacing the "isp" 
> prefix with "omap3isp" (or similar), or moving the driver to 
> drivers/media/video/ti-media/omap3isp, but that will impede code sharing code 
> between the Davinci and OMAP processor families. That's where my uncertainty 
> comes from.

There are two separate points here. The first one is re-using a driver or some
symbols. Whatever directory structure is used, this won't prevent to share the code.
Just create the header files under include/media and be sure that the Kbuild 
system will properly handle the dependencies, with "depends on".

> 
>> Myself and Vaibhav had discussed this in the past and ti-media is the
>> generic name that we could agree on. On DM SoCs (DM6446, DM355, DM365) I
>> expect ti-media to be the home for all vpfe and vpbe driver files. Since
>> we had a case of common IP across OMAP and DMxxx SoCs, we want to place
>> all OMAP and DMxxx video driver files in a common directory so that
>> sharing the drivers across the SoCs will be easy. We could discuss and
>> agree on another name if need be. Any suggestions?
> 
> It's not the name ti-media that I don't agree on, it's just that this will 
> move the problem one step further in the directory hierarchy without actually 
> solving it :-)
> 
> Is it guaranteed today that no TI processors with new generation video blocks 
> will reuse the names ISP, VPFE and VPBE ? The OMAP3 datasheet refers to VPFE 
> and VPBE, but luckily those blocks are further divided into subblocks, and the 
> driver doesn't refer to the VPFE and VPBE directly.

I agree that a name like ti-media would be too generic. Also, if we take a look on
how the drivers are currently organized, the trees aren't vendor-based, but
chipset-design based. There are even some cases where there's just one or two C files that
are directly stored under drivers/media/video (like tvp5150, for example).

IMO, simpler drivers where just one or a couple of files are needed should be stored
into drivers/media/video. Bigger drivers should be organized by family, and not by vendor. 
Otherwise, we would need to re-organize the tree to be coherent.

One interesting example of the a per-family directory is cx25840. The same driver
is used by several different chipsets. The driver supports a separate IC chip (cx25836,
cx2584x), and two designs where the decoder logic is inside an IC chip with the bridge
and other functional blocks (cx23885 and cx231xx).


-- 

Cheers,
Mauro

RE: [Resubmit: PATCH-V2] Introducing ti-media directory

[Karicheri, Muralidharan]

Laurent,

>
>Using a dedicated directory in drivers/media/video for TI-specific cores is
>definitely a good idea (assuming the same IP cores won't be used by other
>vendors in the future).

If another vendor uses it in another SOC (assuming for discussion), then
the driver should be re-used. So there shouldn't be another version of the
driver right? So why is this an issue?

>
>My concern is that, if we move the ISP driver in drivers/media/video/ti-
>media,
>the directory will soon get quite crowded. If a new TI processor comes up
>with
>a totally incompatible ISP, we will get a name conflict in
>drivers/media/video/ti-media. I was thinking about either replacing the
>"isp"
>prefix with "omap3isp" (or similar), or moving the driver to
>drivers/media/video/ti-media/omap3isp, but that will impede code sharing
>code
>between the Davinci and OMAP processor families. That's where my
>uncertainty
>comes from.

I think vpfe is used for DM devices which is equivalent to ISP in OMAP.
omap3 CCDC/Previewer/Resizer/H3A is re-used from DM6446 CCDC or vice-versa. 
The ccdc is also re-used in AM35xxx OMAP device (excuse me if I wrote the name incorrectly) that Vaibhav is working on. So we might want to name it as just ccdc.c/resizer.c/previewer.c. Currently we have dm644x_ccdc.c under davinci for DM644x and dm355_ccdc.c for DM355. We need to sort out the differences in the driver and use a common ccdc.c on OMAP/DM644x/AM35xxx. I am not sure if we have any control on how hardware designers name the IP, and would have to deal with it as it happens. For new IPs that is considerably different, but share the same name might have to be named by adding some prefix/suffix as appropriate (example v1, v2 etc for different versions of the same IP, resizer.c for OMAP/DM644x/AM35xxx, resizer_v1.c for resizer on DM355). 

>
>> Myself and Vaibhav had discussed this in the past and ti-media is the
>> generic name that we could agree on. On DM SoCs (DM6446, DM355, DM365) I
>> expect ti-media to be the home for all vpfe and vpbe driver files. Since
>> we had a case of common IP across OMAP and DMxxx SoCs, we want to place
>> all OMAP and DMxxx video driver files in a common directory so that
>> sharing the drivers across the SoCs will be easy. We could discuss and
>> agree on another name if need be. Any suggestions?
>
>It's not the name ti-media that I don't agree on, it's just that this will
>move the problem one step further in the directory hierarchy without
>actually
>solving it :-)
>
>Is it guaranteed today that no TI processors with new generation video
>blocks
>will reuse the names ISP, VPFE and VPBE ? The OMAP3 datasheet refers to
>VPFE
>and VPBE, but luckily those blocks are further divided into subblocks, and
>the
>driver doesn't refer to the VPFE and VPBE directly.
>

As discussed above, we will have to expect name conflicts in future and come up with some naming convention to name files(and add it to v4 documentation). I think this shouldn't prevent this patch from merging to the tree since you are okay with the name. I will send a pull request if you are okay with this
patch.

>--
>Regards,
>
>Laurent Pinchart

RE: [Resubmit: PATCH-V2] Introducing ti-media directory

[Hiremath, Vaibhav]

> -----Original Message-----
> From: Mauro Carvalho Chehab [mailto:mchehab@redhat.com]
> Sent: Wednesday, March 24, 2010 5:32 PM
> To: Laurent Pinchart
> Cc: Karicheri, Muralidharan; Hiremath, Vaibhav; davinci-linux-open-
> source@linux.davincidsp.com; linux-media@vger.kernel.org
> Subject: Re: [Resubmit: PATCH-V2] Introducing ti-media directory
> 
> Laurent Pinchart wrote:
> > Hi Murali,
> >
> > On Tuesday 23 March 2010 18:52:44 Karicheri, Muralidharan wrote:
> >> Laurent,
> >>
> >>>> I'm not too sure to like the ti-media name. It will soon get quite
> >>>> crowded, and name collisions might occur (look at the linux-omap-camera
> >>>> tree and the ISP driver in there for instance). Isn't there an internal
> >>>> name to refer to both the DM6446 and AM3517 that could be used ?
> >>> [Hiremath, Vaibhav] Laurent,
> >>>
> >>> ti-media directory is top level directory where we are putting all TI
> >>> devices drivers. So having said that, we should worrying about what goes
> >>> inside this directory.
> >>> For me ISP is more generic, if you compare davinci and OMAP.
> >>>
> >>> Frankly, there are various naming convention we do have from device to
> >>> device, even if the IP's are being reused. For example, the internal
> name
> >>> for OMAP is ISP but Davinci refers it as a VPSS.
> >> Could you explain what name space issue you are referring to in
> >> linux-omap-camera since I am not quite familiar with that tree?
> >
> > The linux-omap-camera tree contains a driver for the OMAP3 ISP. Basically,
> > most source files start with the "isp" prefix and are stored in
> > drivers/media/video/isp/.
> >
> > ISP is quite a generic name, and other vendors will probably develop an
> ISP at
> > some point (if not already done), so there's already a potential name
> conflict
> > today.
> >
> > Using a dedicated directory in drivers/media/video for TI-specific cores
> is
> > definitely a good idea (assuming the same IP cores won't be used by other
> > vendors in the future).
> >
> > My concern is that, if we move the ISP driver in drivers/media/video/ti-
> media,
> > the directory will soon get quite crowded. If a new TI processor comes up
> with
> > a totally incompatible ISP, we will get a name conflict in
> > drivers/media/video/ti-media. I was thinking about either replacing the
> "isp"
> > prefix with "omap3isp" (or similar), or moving the driver to
> > drivers/media/video/ti-media/omap3isp, but that will impede code sharing
> code
> > between the Davinci and OMAP processor families. That's where my
> uncertainty
> > comes from.
> 
> There are two separate points here. The first one is re-using a driver or
> some
> symbols. Whatever directory structure is used, this won't prevent to share
> the code.
> Just create the header files under include/media and be sure that the Kbuild
> system will properly handle the dependencies, with "depends on".
> 
> >
> >> Myself and Vaibhav had discussed this in the past and ti-media is the
> >> generic name that we could agree on. On DM SoCs (DM6446, DM355, DM365) I
> >> expect ti-media to be the home for all vpfe and vpbe driver files. Since
> >> we had a case of common IP across OMAP and DMxxx SoCs, we want to place
> >> all OMAP and DMxxx video driver files in a common directory so that
> >> sharing the drivers across the SoCs will be easy. We could discuss and
> >> agree on another name if need be. Any suggestions?
> >
> > It's not the name ti-media that I don't agree on, it's just that this will
> > move the problem one step further in the directory hierarchy without
> actually
> > solving it :-)
> >
> > Is it guaranteed today that no TI processors with new generation video
> blocks
> > will reuse the names ISP, VPFE and VPBE ? The OMAP3 datasheet refers to
> VPFE
> > and VPBE, but luckily those blocks are further divided into subblocks, and
> the
> > driver doesn't refer to the VPFE and VPBE directly.
> 
> I agree that a name like ti-media would be too generic. Also, if we take a
> look on
> how the drivers are currently organized, the trees aren't vendor-based, but
> chipset-design based. There are even some cases where there's just one or
> two C files that
> are directly stored under drivers/media/video (like tvp5150, for example).
> 
> IMO, simpler drivers where just one or a couple of files are needed should
> be stored
> into drivers/media/video. Bigger drivers should be organized by family, and
> not by vendor.
> Otherwise, we would need to re-organize the tree to be coherent.
> 
> One interesting example of the a per-family directory is cx25840. The same
> driver
> is used by several different chipsets. The driver supports a separate IC
> chip (cx25836,
> cx2584x), and two designs where the decoder logic is inside an IC chip with
> the bridge
> and other functional blocks (cx23885 and cx231xx).
> 
[Hiremath, Vaibhav] Mauro and Laurent,

What is the conclusion on this directory naming convention issue? Actually the V4L2 display driver patch (submitted by me) is dependent on this patch, and due to this it is blocked.

As mentioned by Murali, considering the number of files and reusability we come up the ti-media directory naming structure. And also Laurent has admitted that we need to have directory for ti specific device drivers. 

If we go with the Mauro's suggestion (family based directory structure) then the directory structure would look like - 

Drivers/media/video/
			- omap/
			- davinci/
			- ...
			- much more

Why I was not very keen on this approach is, there are some devices publically known as OMAPx device but makes use of some of davinci video IP's. And in the coming future probability of such cris-cross interfacing of IP's are going to increase. So if we create directory with ti-media, easy to understand.

Thanks,
Vaibhav

> 
> --
> 
> Cheers,
> Mauro