Re: [PATCH] media: venus: core: Drop local dma_parms

[Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>]

On 2020-10-02 16:57, Stanimir Varbanov wrote:
> On 10/2/20 11:06 AM, Sai Prakash Ranjan wrote:
>> Hi Robin,
>> 
>> On 2020-09-04 02:44, Robin Murphy wrote:
>>> Since commit 9495b7e92f71 ("driver core: platform: Initialize 
>>> dma_parms
>>> for platform devices"), struct platform_device already provides a
>>> dma_parms structure, so we can save allocating another one.
>>> 
>>> Also the DMA segment size is simply a size, not a bitmask.
>>> 
>>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>>> ---
>>>  drivers/media/platform/qcom/venus/core.c | 8 +-------
>>>  1 file changed, 1 insertion(+), 7 deletions(-)
>>> 
>>> diff --git a/drivers/media/platform/qcom/venus/core.c
>>> b/drivers/media/platform/qcom/venus/core.c
>>> index 203c6538044f..2fa9275d75ff 100644
>>> --- a/drivers/media/platform/qcom/venus/core.c
>>> +++ b/drivers/media/platform/qcom/venus/core.c
>>> @@ -226,13 +226,7 @@ static int venus_probe(struct platform_device 
>>> *pdev)
>>>      if (ret)
>>>          return ret;
>>> 
>>> -    if (!dev->dma_parms) {
>>> -        dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms),
>>> -                          GFP_KERNEL);
>>> -        if (!dev->dma_parms)
>>> -            return -ENOMEM;
>>> -    }
>>> -    dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
>>> +    dma_set_max_seg_size(dev, UINT_MAX);
>>> 
>>>      INIT_LIST_HEAD(&core->instances);
>>>      mutex_init(&core->lock);
>> 
>> This reintroduced dma api debug warning which the original commit was
>> addressing or rather thought it addressed.
>> 
>>  DMA-API: qcom-venus aa00000.video-codec: mapping sg segment longer 
>> than
>> device claims to support [len=4194304] [max=65536]
>>  WARNING: CPU: 3 PID: 5365 at kernel/dma/debug.c:1225
>> debug_dma_map_sg+0x1ac/0x2c8
>>  <...>
>>  pstate: 60400009 (nZCv daif +PAN -UAO)
>>  pc : debug_dma_map_sg+0x1ac/0x2c8
>>  lr : debug_dma_map_sg+0x1ac/0x2c8
>>  sp : ffffff8016517850
>>  x29: ffffff8016517860 x28: 0000000000010000
>>  x27: 00000000ffffffff x26: ffffff80da45eb00
>>  x25: ffffffd03c465000 x24: ffffffd03b3c1000
>>  x23: ffffff803e262d80 x22: ffffff80d9a0d010
>>  x21: 0000000000000001 x20: 0000000000000001
>>  x19: 0000000000000001 x18: 00000000ffff0a10
>>  x17: ffffffd03b84a000 x16: 0000000000000037
>>  x15: ffffffd03a950610 x14: 0000000000000001
>>  x13: 0000000000000000 x12: 00000000a3b31442
>>  x11: 0000000000000000 x10: dfffffd000000001
>>  x9 : f544368f90c5ee00 x8 : f544368f90c5ee00
>>  x7 : ffffffd03af5d570 x6 : 0000000000000000
>>  x5 : 0000000000000080 x4 : 0000000000000001
>>  x3 : ffffffd03a9174b0 x2 : 0000000000000001
>>  x1 : 0000000000000008 x0 : 000000000000007a
>>  Call trace:
>>   debug_dma_map_sg+0x1ac/0x2c8
>>   vb2_dma_sg_alloc+0x274/0x2f4 [videobuf2_dma_sg]
>>   __vb2_queue_alloc+0x14c/0x3b0 [videobuf2_common]
>>   vb2_core_reqbufs+0x234/0x374 [videobuf2_common]
>>   vb2_reqbufs+0x4c/0x64 [videobuf2_v4l2]
>>   v4l2_m2m_reqbufs+0x50/0x84 [v4l2_mem2mem]
>>   v4l2_m2m_ioctl_reqbufs+0x2c/0x38 [v4l2_mem2mem]
>>   v4l_reqbufs+0x4c/0x5c
>>   __video_do_ioctl+0x2cc/0x3e0
>>   video_usercopy+0x3b0/0x910
>>   video_ioctl2+0x38/0x48
>>   v4l2_ioctl+0x6c/0x80
>>   do_video_ioctl+0xb54/0x2708
>>   v4l2_compat_ioctl32+0x5c/0xcc
>>   __se_compat_sys_ioctl+0x100/0x2064
>>   __arm64_compat_sys_ioctl+0x20/0x2c
>>   el0_svc_common+0xa8/0x178
>>   el0_svc_compat_handler+0x2c/0x40
>>   el0_svc_compat+0x8/0x10
>> 
>> Thanks,
>> Sai
>> 
> 
> Do you have the mentioned above commit when you see this warning ?

+Stephen reported this, this was recently backported to 5.4 kernel
where playing youtube with dma api debug enabled would throw this
warning and I am almost 100% certain this is the commit which caused
the warning to appear again.

Thanks,
Sai

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