Hello Hans,

On 19.01.2015 11:38, Hans Verkuil wrote:
> Sorry for the delay.
No problem, thanks for your feedback.

>> Note: I'm intentionally using dma-contig instead of vmalloc, as the USB
>> core apparently _will_ try to use DMA for larger bulk transfers. 
> As far as I can tell from looking through the usb core code it supports
> scatter-gather DMA, so you should at least use dma-sg rather than dma-contig.
> Physically contiguous memory should always be avoided.
OK, will this work transparently (i.e. just switch from *-contig-* to
*-sg-*)? If not, can you suggest an example driver to use as template?

> I'm also missing a patch for the Kconfig that adds a dependency on 
> MEDIA_USB_SUPPORT
> and that selects VIDEOBUF2_DMA_SG.
Good point, will add that.

>> +err_unreg_video:
>> +    video_unregister_device(&sur40->vdev);
>> +err_unreg_v4l2:
>> +    v4l2_device_unregister(&sur40->v4l2);
>>  err_free_buffer:
>>      kfree(sur40->bulk_in_buffer);
>>  err_free_polldev:
>> @@ -436,6 +604,10 @@ static void sur40_disconnect(struct usb_interface 
>> *interface)
> Is this a hardwired device or hotpluggable? If it is hardwired, then this 
> code is
> OK, but if it is hotpluggable, then this isn't good enough.
It's hardwired. Out of curiosity, what would I have to change for a
hotpluggable one?

>> +    i->type = V4L2_INPUT_TYPE_CAMERA;
>> +    i->std = V4L2_STD_UNKNOWN;
>> +    strlcpy(i->name, "In-Cell Sensor", sizeof(i->name));
> Perhaps just say "Sensor" here? I'm not sure what "In-Cell" means.
In-cell is referring to the concept of integrating sensor pixels
directly with LCD pixels, I think it's what Samsung calls it.

Thanks & best regards, Florian
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