lkml.org 
[lkml]   [2015]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] drivers: dma-coherent: use ioremap_wc() for DMA_MEMORY_MAP
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 <brian.starkey@arm.com>
>Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>---
> 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
>linux-arm-kernel@lists.infradead.org
>http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>


\
 
 \ /
  Last update: 2015-12-04 12:01    [W:3.665 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site