On 02/12/10 08:12, ext G, Manjunath Kondaiah wrote:
* Adrian Hunter<adrian.hunter@xxxxxxxxx> [2010-12-01 22:16:44 +0200]:
On 01/12/10 20:47, ext 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.
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@xxxxxx>
Cc: Kevin Hilman<khilman@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Walmsley<paul@xxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
---
Change summary:
v3: Review comments incorporated for:
https://patchwork.kernel.org/patch/282212/
v4: added mutex changes
v5: typo fixes for errata and erratum
v6: fixed oh increment bug and also mutex(missing in v5)
arch/arm/mach-omap2/omap_hwmod.c | 47 +++++++++++++++++++-
arch/arm/plat-omap/include/plat/omap_device.h | 2 +
arch/arm/plat-omap/include/plat/omap_hwmod.h | 4 +-
arch/arm/plat-omap/omap_device.c | 60 +++++++++++++++++++++++++
4 files changed, 111 insertions(+), 2 deletions(-)
Does not seem to handle overlapping requests to set/clear
midle mode.
We can have use count so that we can avoid register access during
middle of operation if mstandby mode is already changed to "no standby"
mode.
Exactly
Also, there is a mutex but don't these functions get called
sometimes in interrupt context?
I feel we should leave this to caller of these API's. The caller should
make sure that, he disables interrupts if it is used in interrupt context.
How does that help? It seems to me that a mutex cannot be used for this.
-Manjunath
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