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mtd: ams-delta: fix request_mem_region() failure
A call to request_mem_region() has been introduced in the omap-gpio driver recently (commit 96751fcb, "gpio/omap: Use devm_ API and add request_mem_region"). This change prevented the Amstrad Delta NAND driver, which was doing the same in order to take control over OMAP MPU I/O lines that the NAND device hangs off, from loading successfully. The I/O lines and corresponding registers used by the NAND driver are a subset of those used for the GPIO function. Then, to avoid run time collisions, all MPUIO GPIO lines should be marked as requested while initializing the NAND driver, and vice versa, a single MPUIO GPIO line already requested before the NAND driver initialization is attempted should prevent the NAND device from being started successfully. There is another driver, omap-keypad, which also manipulates MPUIO registers, but has never been calling request_mem_region() on startup, so it's not affected by the change in the gpio-omap and works correctly. It uses the depreciated omap_read/write functions for accessing MPUIO registers. Unlike the NAND driver, these I/O lines and registers are separate from those used by the GPIO driver. However, both register sets are non-contiguous and overlapping, so it would be impractical to request the two sets separately, one from the gpio-omap, the other form the omap-keypad driver. In order to solve all these issues correctly, a solution first suggested by Artem Bityutskiy, then closer specified by Tony Lindgren while they commented the initial version of this fix, should be implemented. The gpio-omap driver should export a few functions which would allow the other two drivers to access MPUIO registers in a safe manner instead of trying to manage them in parallel to the GPIO driver. However, such a big change, affecting 3 drivers all together, is not suitable for the rc cycle, and should be prepared for the merge window. Then, an alternative solution is proposed as a regression fix. For the ams-delta NAND driver to initialize correctly in coexistence with the changed GPIO driver, drop the request_mem_region() call from the former, especially as this call is going to be removed while the long-term solution is implemented. Tested on Amstrad Delta. Signed-off-by:Janusz Krzysztofik <jkrzyszt@tis.icnet.pl> Acked-by: