Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1261693

Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions

Show all headers | View raw

On 11/3/2015 11:10 AM, Vinod Koul wrote:
> On Tue, Nov 03, 2015 at 08:31:57AM -0600, Timur Tabi wrote:
>> Sinan Kaya wrote:
>>>
>>> Almost all DMA engine drivers come with some sort of selftest code
>>> called from probe. I followed the same design pattern.
>>
>> As others have said, it appears that's outdated.
>>
>> Is there a real possibility that the hardware could fail the test
>> without trashing the system?  It seems that if the DMA engine is
>> faulty, it won't "politely" fail.  The whole system will crash or
>> some memory will get corrupted and you won't know it.
>
> Failing politely would be right thing to do. If DMA starts sending data to
> anywhere in system memory due to bug or wrong addresses we can't do
> anything to prevent that
>
I have seen failures in three cases so far. These are the reasons, why I 
want to keep these runtime tests around.

1. Bug in ARM64 DMA subsystem.
2. Bug in IOMMU driver.
3. Bug in another newly introduced driver. The new driver would hog the 
CPU and won't allow HIDMA interrupts to execute. Therefore, the test 
times out.

In my code, when test fails; I abort all transactions in flight and 
shutdown and deregister the HIDMA driver.

Of course, there is a small window of oppurtunity; where DMA can dump 
data to incorrect place if HW was faulty right before I abort the 
transaction.

-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-02 07:10 +0100
  Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-03 05:20 +0100
    Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-03 07:40 +0100
      Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Dan Williams <dan.j.williams@intel.com> - 2015-11-03 08:50 +0100
        Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Andy Shevchenko <andy.shevchenko@gmail.com> - 2015-11-03 09:30 +0100
          Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-03 17:10 +0100
            Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-05 03:50 +0100
              Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-05 13:10 +0100
                Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-05 17:20 +0100
                Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-07 07:30 +0100
                Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-08 15:00 +0100
                Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support  functions okaya@codeaurora.org - 2015-11-13 21:30 +0100
        Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-03 17:00 +0100
        Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-03 17:10 +0100
    Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Timur Tabi <timur@codeaurora.org> - 2015-11-03 15:40 +0100
      Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-03 17:10 +0100
        Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-03 17:30 +0100
          Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Timur Tabi <timur@codeaurora.org> - 2015-11-03 17:50 +0100
            Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Sinan Kaya <okaya@codeaurora.org> - 2015-11-03 18:00 +0100
        Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Timur Tabi <timur@codeaurora.org> - 2015-11-03 17:50 +0100
  Re: [PATCH V2 2/3] dmaselftest: add memcpy selftest support functions Vinod Koul <vinod.koul@intel.com> - 2015-11-03 05:20 +0100

csiph-web