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@xxxxxx> Cc: Kevin Hilman<khilman@xxxxxxxxxxxxxxxxxxx> Cc: Paul Walmsley<paul@xxxxxxxxx> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
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 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
