AR9882 IOMMU faults

[Ben Skeggs]

On 07/08/2016 11:57 PM, Ben Greear wrote:
> 
> 
> On 07/08/2016 06:09 AM, Manoharan, Rajkumar wrote:
>> Logs are so limited. If possible, revert below commit and give a try
>>
>> "ath10k: do not use coherent memory for allocated device memory chunks"
>>
>> If revert is not so clean, try with this patch.
>>
>> https://patchwork.kernel.org/patch/9175029/
> 
> I use this patch, I don't think it is upstream, and per comment, I have not
> tested this on other than x86 platform:
Both the revert, and the change too DMA_BIDIRECTIONAL seem to resolve
the issue here (also on x86).

Thank you!
Ben.

> 
> [greearb at ben-dt ath10k]$ git show 0e6e6f6b2
> commit 0e6e6f6b2fac0ade990de56eef3841dbe7128f35
> Author: Ben Greear <greearb at candelatech.com>
> Date:   Thu Jan 21 18:57:11 2016 -0800
> 
>     ath10k:  wmi-alloc-chunk should use DMA_BIDIRECTIONAL.
> 
>     These memory chunks are often used as 'swap' by the NIC,
>     so it will be both reading and writing to these areas.
> 
>     This seems to fix errors like this on my x86-64 machine:
> 
>     kernel: DMAR: DMAR:[DMA Write] Request device [05:00.0] fault addr
> ff5de000
>             DMAR:[fault reason 05] PTE Write access is not set
> 
>     Should be tested and verified by someone who uses other platforms
>     though...
> 
>     Signed-off-by: Ben Greear <greearb at candelatech.com>
> 
> diff --git a/drivers/net/wireless/ath/ath10k/wmi.c
> b/drivers/net/wireless/ath/ath10k/wmi.c
> index af37a77..502f0e0 100644
> --- a/drivers/net/wireless/ath/ath10k/wmi.c
> +++ b/drivers/net/wireless/ath/ath10k/wmi.c
> @@ -4404,7 +4404,7 @@ static int ath10k_wmi_alloc_chunk(struct ath10k
> *ar, u32 req_id,
>         if (!num_units)
>                 return -ENOMEM;
> 
> -       paddr = dma_map_single(ar->dev, vaddr, pool_size, DMA_TO_DEVICE);
> +       paddr = dma_map_single(ar->dev, vaddr, pool_size,
> DMA_BIDIRECTIONAL);
>         if (dma_mapping_error(ar->dev, paddr)) {
>                 kfree(vaddr);
>                 return -ENOMEM;
> [greearb at ben-dt ath10k]$
> 
>>
>> -Rajkumar
>> ________________________________________
>> From: ath10k <ath10k-bounces at lists.infradead.org> on behalf of Ben
>> Skeggs <bskeggs at redhat.com>
>> Sent: Friday, July 8, 2016 10:59 AM
>> To: ath10k at lists.infradead.org
>> Subject: AR9882 IOMMU faults
>>
>> Hey,
>>
>> I've just installed a COMPEX WLE600VX (AR9882) in my router machine,
>> operating in AP mode.
>>
>> While it appears to be working well enough, I get massive floods of
>> IOMMU faults reported in my kernel log.  These appear to increase with
>> the load on the network.
>>
>> I've attached both the info that ath10k reports when it detects the
>> device, and a sample of one of the DMAR messages (worth nothing that
>> it's the same fault address in all the messages).
>>
>> Is this a known issue, and anything I can do to help get it resolved?
>>
>> Thanks,
>> Ben.
>>
>> _______________________________________________
>> ath10k mailing list
>> ath10k at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/ath10k
>>
> 

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