Hi, Is there anything I can do to help get this merged? It fixes a real problem we have on our arm64 development boards.
From my reading of Documentation/DMA-API.txt it seems like this was
the intended behavior in the first place. Best regards, Brian On Fri, Nov 20, 2015 at 02:20:26PM +0000, Brian Starkey wrote:
When the DMA_MEMORY_MAP flag is used, memory which can be accessed directly should be returned, so use ioremap_wc() instead of ioremap(). Also, ensure that the correct memset operation is used in dma_alloc_from_coherent() with respect to the region's flags. This fixes the below alignment fault on arm64, caused by invalid use of memset() on Device memory. Unhandled fault: alignment fault (0x96000061) at 0xffffff8000380000 Internal error: : 96000061 [#1] PREEMPT SMP Modules linked in: hdlcd(+) clk_scpi CPU: 4 PID: 1355 Comm: systemd-udevd Not tainted 4.4.0-rc1+ #5 Hardware name: ARM Juno development board (r0) (DT) task: ffffffc9763eee00 ti: ffffffc9758c4000 task.ti: ffffffc9758c4000 PC is at __efistub_memset+0x1ac/0x200 LR is at dma_alloc_from_coherent+0xb0/0x120 pc : [<ffffffc00030ff2c>] lr : [<ffffffc00042a918>] pstate: 400001c5 sp : ffffffc9758c79a0 x29: ffffffc9758c79a0 x28: ffffffc000635cd0 x27: 0000000000000124 x26: ffffffc000119ef4 x25: 0000000000010000 x24: 0000000000000140 x23: ffffffc07e9ac3a8 x22: ffffffc9758c7a58 x21: ffffffc9758c7a68 x20: 0000000000000004 x19: ffffffc07e9ac380 x18: 0000000000000001 x17: 0000007fae1bbba8 x16: ffffffc0001b2d1c x15: ffffffffffffffff x14: 0ffffffffffffffe x13: 0000000000000010 x12: ffffff800837ffff x11: ffffff800837ffff x10: 0000000040000000 x9 : 0000000000000000 x8 : ffffff8000380000 x7 : 0000000000000000 x6 : 000000000000003f x5 : 0000000000000040 x4 : 0000000000000000 x3 : 0000000000000004 x2 : 000000000000ffc0 x1 : 0000000000000000 x0 : ffffff8000380000 Signed-off-by: Brian Starkey <[email protected]> Reviewed-by: Catalin Marinas <[email protected]> --- drivers/base/dma-coherent.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c index 55b8398..45358d0 100644 --- a/drivers/base/dma-coherent.c +++ b/drivers/base/dma-coherent.c @@ -31,7 +31,10 @@ static int dma_init_coherent_memory(phys_addr_t phys_addr, dma_addr_t device_add if (!size) goto out; - mem_base = ioremap(phys_addr, size); + if (flags & DMA_MEMORY_MAP) + mem_base = ioremap_wc(phys_addr, size); + else + mem_base = ioremap(phys_addr, size); if (!mem_base) goto out; @@ -181,7 +184,10 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size, */ *dma_handle = mem->device_base + (pageno << PAGE_SHIFT); *ret = mem->virt_base + (pageno << PAGE_SHIFT); - memset(*ret, 0, size); + if (mem->flags & DMA_MEMORY_MAP) + memset(*ret, 0, size); + else + memset_io(*ret, 0, size); spin_unlock_irqrestore(&mem->spinlock, flags); return 1; -- 1.7.9.5 _______________________________________________ linux-arm-kernel mailing list [email protected] http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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