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<manj...@ti.com>
Cc: Kevin Hilman<khil...@deeprootsystems.com>
Cc: Paul Walmsley<p...@pwsan.com>
Cc: linux-arm-ker...@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
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