[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[G, Manjunath Kondaiah]

* G, Manjunath Kondaiah <manjugk@ti.com> [2010-12-02 19:29:52 +0530]:

> Certain errata in OMAP2+ processors will require forcing
> master standby to "no standby" mode before completing on going
> operation. Without this, the results will be unpredictable.
> 
> Since current implementation of PM run time framework does not support
> changing sysconfig settings during middle of the on going operation,
> these API's will support the same. One API will force the device's
> sysconfig mstandby mode settings to "no standby" and other API will
> release "no standby" mode and sets it to "smart standby" or "no
> standby? depending on HWMOD_SWSUP_MSTANDBY value.
> 
> The hwmod API "omap_hwmod_set_master_standbymode" will use
> no_stdby_cnt(introduced in omap_hwmod structure) for controlling
> access to sysconfig register settings in case of overlapping
> request/release API's are called. It also disables interrupts during
> syconfig register access.
> 
> These API's should be used by device drivers only incase of
> erratum applicable to their modules if there is no other methods
> to resolve.
> 
> These API's are required for multiple DMA errata which require
> putting DMA controller in no mstandby mode before stopping dma.
> 
> The applicable errata:
> 1. Erratum ID: i557(Applicable for omap36xx all ES versions)
> The channel hangs when the Pause bit (DMA4_CDPi [7] ) is cleared
> through config port while in Standby.
> 
> 2. Erratum ID: i541
> sDMA FIFO draining does not finish. Applicable to all omap2+ except
> omap4.
> 
> 3. Erratum ID:i88
> The sDMA to be put in no mstandby mode before disabling the channel
> after completing the data transfer operation.
> Applicable only for OMAP3430 ES1.0
> 
> Also fixes typo HWMOD_SWSUP_MSTDBY to HWMOD_SWSUP_MSTANDBY in
> omap_hwmod.h
> 
> Signed-off-by: G, Manjunath Kondaiah <manjugk@ti.com>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> Cc: Paul Walmsley <paul@pwsan.com>
> Cc: linux-arm-kernel at lists.infradead.org

Pls ignore this patch. I have resent this patch as:
[PATCH v7 RESEND] OMAP2+: PM: omap device: API's for handling mstandby
mode

Sorry for noise.

-Manjunath

[...]

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[Cousson, Benoit]

On 12/2/2010 2:59 PM, G, Manjunath Kondaiah wrote:
> Certain errata in OMAP2+ processors will require forcing
> master standby to "no standby" mode before completing on going
> operation. Without this, the results will be unpredictable.
>
> Since current implementation of PM run time framework does not support
> changing sysconfig settings during middle of the on going operation,
> these API's will support the same. One API will force the device's
> sysconfig mstandby mode settings to "no standby" and other API will
> release "no standby" mode and sets it to "smart standby" or "no
> standby? depending on HWMOD_SWSUP_MSTANDBY value.
>
> The hwmod API "omap_hwmod_set_master_standbymode" will use
> no_stdby_cnt(introduced in omap_hwmod structure) for controlling
> access to sysconfig register settings in case of overlapping
> request/release API's are called. It also disables interrupts during
> syconfig register access.
>
> These API's should be used by device drivers only incase of
> erratum applicable to their modules if there is no other methods
> to resolve.
>
> These API's are required for multiple DMA errata which require
> putting DMA controller in no mstandby mode before stopping dma.
>
> The applicable errata:
> 1. Erratum ID: i557(Applicable for omap36xx all ES versions)
> The channel hangs when the Pause bit (DMA4_CDPi [7] ) is cleared
> through config port while in Standby.
>
> 2. Erratum ID: i541
> sDMA FIFO draining does not finish. Applicable to all omap2+ except
> omap4.
>
> 3. Erratum ID:i88
> The sDMA to be put in no mstandby mode before disabling the channel
> after completing the data transfer operation.
> Applicable only for OMAP3430 ES1.0
>
> Also fixes typo HWMOD_SWSUP_MSTDBY to HWMOD_SWSUP_MSTANDBY in
> omap_hwmod.h
>
> Signed-off-by: G, Manjunath Kondaiah<manjugk@ti.com>
> Cc: Kevin Hilman<khilman@deeprootsystems.com>
> Cc: Paul Walmsley<paul@pwsan.com>
> Cc: linux-arm-kernel at lists.infradead.org

You have to CC lakml during send-email, but it should not be in the 
changelog.

On the other hand, it is a good practice to add all the authors of the 
file you change in CC.

> ---
> v3: Review comments incorporated for:
> https://patchwork.kernel.org/patch/282212/
>
> v4: added mutex changes
> https://patchwork.kernel.org/patch/338611/
>
> v5: typo fixes for errata and erratum
> https://patchwork.kernel.org/patch/352481/
>
> v6: fixed oh increment bug and also mutex(missing in v5)
> https://patchwork.kernel.org/patch/372231/
>
> v7: replaced mutex lock with spin lock. Added use count for controlling
> access to sysconfig registers in case if overlapping request/release API's
> are used.

I'm not sure it should be done here. I'd rather keep that code in the 
DMA, since this is the only user of that feature.
These hwmod APIs are rather low level and should never be used except 
for workaround. So I'd prefer keeping this API simple and not sexy at 
all in order to prevent people to abuse it.

Regards,
Benoit

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[G, Manjunath Kondaiah]

* Cousson, Benoit <b-cousson@ti.com> [2010-12-03 09:38:35 +0100]:

> On 12/2/2010 2:59 PM, G, Manjunath Kondaiah wrote:
> >Certain errata in OMAP2+ processors will require forcing
> >master standby to "no standby" mode before completing on going
> >operation. Without this, the results will be unpredictable.
> >
> >Since current implementation of PM run time framework does not support
> >changing sysconfig settings during middle of the on going operation,
> >these API's will support the same. One API will force the device's
> >sysconfig mstandby mode settings to "no standby" and other API will
> >release "no standby" mode and sets it to "smart standby" or "no
> >standby? depending on HWMOD_SWSUP_MSTANDBY value.
> >
> >The hwmod API "omap_hwmod_set_master_standbymode" will use
> >no_stdby_cnt(introduced in omap_hwmod structure) for controlling
> >access to sysconfig register settings in case of overlapping
> >request/release API's are called. It also disables interrupts during
> >syconfig register access.
> >
> >These API's should be used by device drivers only incase of
> >erratum applicable to their modules if there is no other methods
> >to resolve.
> >
> >These API's are required for multiple DMA errata which require
> >putting DMA controller in no mstandby mode before stopping dma.
> >
> >The applicable errata:
> >1. Erratum ID: i557(Applicable for omap36xx all ES versions)
> >The channel hangs when the Pause bit (DMA4_CDPi [7] ) is cleared
> >through config port while in Standby.
> >
> >2. Erratum ID: i541
> >sDMA FIFO draining does not finish. Applicable to all omap2+ except
> >omap4.
> >
> >3. Erratum ID:i88
> >The sDMA to be put in no mstandby mode before disabling the channel
> >after completing the data transfer operation.
> >Applicable only for OMAP3430 ES1.0
> >
> >Also fixes typo HWMOD_SWSUP_MSTDBY to HWMOD_SWSUP_MSTANDBY in
> >omap_hwmod.h
> >
> >Signed-off-by: G, Manjunath Kondaiah<manjugk@ti.com>
> >Cc: Kevin Hilman<khilman@deeprootsystems.com>
> >Cc: Paul Walmsley<paul@pwsan.com>
> >Cc: linux-arm-kernel at lists.infradead.org
> 
> You have to CC lakml during send-email, but it should not be in the
> changelog.
> 
> On the other hand, it is a good practice to add all the authors of
> the file you change in CC.
> 
> >---
> >v3: Review comments incorporated for:
> >https://patchwork.kernel.org/patch/282212/
> >
> >v4: added mutex changes
> >https://patchwork.kernel.org/patch/338611/
> >
> >v5: typo fixes for errata and erratum
> >https://patchwork.kernel.org/patch/352481/
> >
> >v6: fixed oh increment bug and also mutex(missing in v5)
> >https://patchwork.kernel.org/patch/372231/
> >
> >v7: replaced mutex lock with spin lock. Added use count for controlling
> >access to sysconfig registers in case if overlapping request/release API's
> >are used.
> 
> I'm not sure it should be done here. I'd rather keep that code in
> the DMA, since this is the only user of that feature.

Are you referring to spin lock or usage count? 

-Manjunath

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[Cousson, Benoit]

On 12/3/2010 10:47 AM, G, Manjunath Kondaiah wrote:
> * Cousson, Benoit<b-cousson@ti.com>  [2010-12-03 09:38:35 +0100]:

[...]

>>> v7: replaced mutex lock with spin lock. Added use count for controlling
>>> access to sysconfig registers in case if overlapping request/release API's
>>> are used.
>>
>> I'm not sure it should be done here. I'd rather keep that code in
>> the DMA, since this is the only user of that feature.
>
> Are you referring to spin lock or usage count?

The spinlock is needed, I was referring to the usage count.

That being said, the API proposed by Paul (request/release
) sound like a get/put, so maybe he had that kind of usage in mind.

I'm still not convince it should be done at hwmod API level.


Paul,
Any thoughts on that?

Regards,
Benoit

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[G, Manjunath Kondaiah]

Paul/Benoit,

On Fri, Dec 03, 2010 at 01:19:06PM +0100, Cousson, Benoit wrote:
> On 12/3/2010 10:47 AM, G, Manjunath Kondaiah wrote:
> >* Cousson, Benoit<b-cousson@ti.com>  [2010-12-03 09:38:35 +0100]:
> 
> [...]
> 
> >>>v7: replaced mutex lock with spin lock. Added use count for controlling
> >>>access to sysconfig registers in case if overlapping request/release API's
> >>>are used.
> >>
> >>I'm not sure it should be done here. I'd rather keep that code in
> >>the DMA, since this is the only user of that feature.
> >
> >Are you referring to spin lock or usage count?
> 
> The spinlock is needed, I was referring to the usage count.
> 
> That being said, the API proposed by Paul (request/release
> ) sound like a get/put, so maybe he had that kind of usage in mind.
> 
> I'm still not convince it should be done at hwmod API level.
> 
> 
> Paul,
> Any thoughts on that?

How do we proceed further?

-Manjunath

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[G, Manjunath Kondaiah]

Paul/Benoit,

On Tue, Dec 14, 2010 at 07:18:22AM +0530, G, Manjunath Kondaiah wrote:
> Paul/Benoit,
> 
> On Fri, Dec 03, 2010 at 01:19:06PM +0100, Cousson, Benoit wrote:
> > On 12/3/2010 10:47 AM, G, Manjunath Kondaiah wrote:
> > >* Cousson, Benoit<b-cousson@ti.com>  [2010-12-03 09:38:35 +0100]:
> > 
> > [...]
> > 
> > >>>v7: replaced mutex lock with spin lock. Added use count for controlling
> > >>>access to sysconfig registers in case if overlapping request/release API's
> > >>>are used.
> > >>
> > >>I'm not sure it should be done here. I'd rather keep that code in
> > >>the DMA, since this is the only user of that feature.
> > >
> > >Are you referring to spin lock or usage count?
> > 
> > The spinlock is needed, I was referring to the usage count.
> > 
> > That being said, the API proposed by Paul (request/release
> > ) sound like a get/put, so maybe he had that kind of usage in mind.
> > 
> > I'm still not convince it should be done at hwmod API level.
> > 
> > 
> > Paul,
> > Any thoughts on that?
> 
> How do we proceed further?
Gentle reminder!

Can we please align on this so that DMA sysconfig patches can be
upstreamed?

Discussion on this topic can be accessed at:
https://patchwork.kernel.org/patch/372231/
http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39728.html

-Manjunath

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[G, Manjunath Kondaiah]

On Mon, Jan 24, 2011 at 03:03:49PM +0530, G, Manjunath Kondaiah wrote:
> Paul/Benoit,
> 
> On Tue, Dec 14, 2010 at 07:18:22AM +0530, G, Manjunath Kondaiah wrote:
> > Paul/Benoit,
> > 
> > On Fri, Dec 03, 2010 at 01:19:06PM +0100, Cousson, Benoit wrote:
> > > On 12/3/2010 10:47 AM, G, Manjunath Kondaiah wrote:
> > > >* Cousson, Benoit<b-cousson@ti.com>  [2010-12-03 09:38:35 +0100]:
> > > 
> > > [...]
> > > 
> > > >>>v7: replaced mutex lock with spin lock. Added use count for controlling
> > > >>>access to sysconfig registers in case if overlapping request/release API's
> > > >>>are used.
> > > >>
> > > >>I'm not sure it should be done here. I'd rather keep that code in
> > > >>the DMA, since this is the only user of that feature.
> > > >
> > > >Are you referring to spin lock or usage count?
> > > 
> > > The spinlock is needed, I was referring to the usage count.
> > > 
> > > That being said, the API proposed by Paul (request/release
> > > ) sound like a get/put, so maybe he had that kind of usage in mind.
> > > 
> > > I'm still not convince it should be done at hwmod API level.
> > > 
> > > 
> > > Paul,
> > > Any thoughts on that?
> > 
> > How do we proceed further?
> Gentle reminder!
> 
> Can we please align on this so that DMA sysconfig patches can be
> upstreamed?
> 
> Discussion on this topic can be accessed at:
> https://patchwork.kernel.org/patch/372231/
> http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39728.html

As there is no response from paul on this topic, I will go ahead with usage
count logic proposed by Adrian Hunter <adrian.hunter@nokia.com> at:
https://patchwork.kernel.org/patch/366831/
Above logic has got:
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>

-Manjunath

[PATCH v7] OMAP2+: PM: omap device: API's for handling mstandby mode

[Paul Walmsley]

On Wed, 26 Jan 2011, G, Manjunath Kondaiah wrote:

> On Mon, Jan 24, 2011 at 03:03:49PM +0530, G, Manjunath Kondaiah wrote:
> > Paul/Benoit,
> > 
> > On Tue, Dec 14, 2010 at 07:18:22AM +0530, G, Manjunath Kondaiah wrote:
> > > Paul/Benoit,
> > > 
> > > On Fri, Dec 03, 2010 at 01:19:06PM +0100, Cousson, Benoit wrote:
> > > > On 12/3/2010 10:47 AM, G, Manjunath Kondaiah wrote:
> > > > >* Cousson, Benoit<b-cousson@ti.com>  [2010-12-03 09:38:35 +0100]:
> > > > 
> > > > [...]
> > > > 
> > > > >>>v7: replaced mutex lock with spin lock. Added use count for controlling
> > > > >>>access to sysconfig registers in case if overlapping request/release API's
> > > > >>>are used.
> > > > >>
> > > > >>I'm not sure it should be done here. I'd rather keep that code in
> > > > >>the DMA, since this is the only user of that feature.
> > > > >
> > > > >Are you referring to spin lock or usage count?
> > > > 
> > > > The spinlock is needed, I was referring to the usage count.
> > > > 
> > > > That being said, the API proposed by Paul (request/release
> > > > ) sound like a get/put, so maybe he had that kind of usage in mind.
> > > > 
> > > > I'm still not convince it should be done at hwmod API level.
> > > > 
> > > > 
> > > > Paul,
> > > > Any thoughts on that?
> > > 
> > > How do we proceed further?
> > Gentle reminder!
> > 
> > Can we please align on this so that DMA sysconfig patches can be
> > upstreamed?
> > 
> > Discussion on this topic can be accessed at:
> > https://patchwork.kernel.org/patch/372231/
> > http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39728.html
> 
> As there is no response from paul on this topic, I will go ahead with usage
> count logic proposed by Adrian Hunter <adrian.hunter@nokia.com> at:
> https://patchwork.kernel.org/patch/366831/
> Above logic has got:
> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
> Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>

Yes, that's probably a good idea for right now.  There's a wider spectrum 
of opinion than I had thought on whether this type of thing belongs in the 
hwmod code.  I'd like to have a greater degree of alignment on that before 
we merge something into the hwmod code.

So, unless there is some reason why it will cause problems not to have 
this in the hwmod code for right now, please just go ahead and deal with 
it in your DMA code, and then we will move it to the hwmod code later as 
needed.


- Paul