i2c: qup: Fix broken dma when CONFIG_DEBUG_SG is enabled
With CONFIG_DEBUG_SG is enabled and when dma mode is used, below dump is seen, ------------[ cut here ]------------ kernel BUG at include/linux/scatterlist.h:140! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-00459-g9f087b9-dirty #7 Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) task: ffffffc036868000 ti: ffffffc036870000 task.ti: ffffffc036870000 PC is at qup_sg_set_buf.isra.13+0x138/0x154 LR is at qup_sg_set_buf.isra.13+0x50/0x154 pc : [<ffffffc0005a0ed8>] lr : [<ffffffc0005a0df0>] pstate: 60000145 sp : ffffffc0368735c0 x29: ffffffc0368735c0 x28: ffffffc036873752 x27: ffffffc035233018 x26: ffffffc000c4e000 x25: 0000000000000000 x24: 0000000000000004 x23: 0000000000000000 x22: ffffffc035233668 x21: ffffff80004e3000 x20: ffffffc0352e0018 x19: 0000004000000000 x18: 0000000000000028 x17: 0000000000000004 x16: ffffffc0017a39c8 x15: 0000000000001cdf x14: ffffffc0019929d8 x13: ffffffc0352e0018 x12: 0000000000000000 x11: 0000000000000001 x10: 0000000000000001 x9 : ffffffc0012b2d70 x8 : ffffff80004e3000 x7 : 0000000000000018 x6 : 0000000030000000 x5 : ffffffc00199f018 x4 : ffffffc035233018 x3 : 0000000000000004 x2 : 00000000c0000000 x1 : 0000000000000003 x0 : 0000000000000000 Process swapper/0 (pid: 1, stack limit = 0xffffffc036870020) Stack: (0xffffffc0368735c0 to 0xffffffc036874000) sg_set_bug expects that the buf parameter passed in should be from lowmem and a valid pageframe. This is not true for pages from dma_alloc_coherent which can be carveouts, hence the check fails. Change allocation of sg buffers from dma_coherent memory to kzalloc to fix the issue. Note that now dma_map/unmap is used to make the kzalloc'ed buffers coherent before passing it to the dmaengine. Signed-off-by: NSricharan R <sricharan@codeaurora.org> Reviewed-by: NAndy Gross <andy.gross@linaro.org> Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
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