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由 Janusz Krzysztofik 提交于
Change the way McBSP registers are updated: use cached values instead of relying upon those read back from the device. With this patch, I have finally managed to get rid of all random playback/recording hangups on my OMAP1510 based Amstrad Delta hardware. Before that, values read back from McBSP registers to be used for updating them happened to be errornous. From the hardware side, the issue appeared to be caused by a relatively high power requirements of an external USB adapter connected to the board's printer dedicated USB port. I think there is one important point that makes this patch worth of applying, apart from my hardware quality. With the current code, if it ever happens to any machine, no matter if OMAP1510 or newer, to read incorrect value from a McBSP register, this wrong value will get written back without any checking. That can lead to hardware damage if, for example, an input pin is turned into output as a result. Applies on top of patch 3 from this series: [PATCH v9 3/4] OMAP: McBSP: Introduce caching in register write operations Tested on OMAP1510 based Amstrad Delta using linux-omap for-next, commit fb7380d70e041e4b3892f6b19dff7efb609d15a4 (2.6.33-rc3+ dated 2010-01-11). Compile-tested with omap_3430sdp_defconfig. Signed-off-by: NJanusz Krzysztofik <jkrzyszt@tis.icnet.pl> Acked-by: NPeter Ujfalusi <peter.ujfalusi@nokia.com> Acked-by: NJarkko Nikula <jhnikula@gmail.com> Signed-off-by: NTony Lindgren <tony@atomide.com>
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