>-----Original Message----- >From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media- >owner@xxxxxxxxxxxxxxx] On Behalf Of Hans Verkuil >Sent: Thursday, July 30, 2009 10:57 AM >To: Karicheri, Muralidharan >Cc: Laurent Pinchart; Mauro Carvalho Chehab; Dongsoo, Nathaniel Kim; >v4l2_linux; Dongsoo Kim; 박경민; jm105.lee@xxxxxxxxxxx; >�세문; 대�기; 김ؕ준 >Subject: RE: How to save number of times using memcpy? > > >> Mauro, >> >> What do you suggest for this? Could we allocate coherent device memory >> using dma_declare_coherent_memory() ? This seems the only way to do it >> unless, video buffer layer does this when initializing the queue. > >Or to be able to override the memory allocation in some way. Large >contiguous buffers are hard to get once a system has been running for a >while, so at least some buffers must be allocated up front and not on the >first open() or VIDIOC_REQBUFS call. I'm surprised that this issue hasn't >cropped up before. > Hans, Our internal test team has already found this an issue in vpfe capture.c. I was about to send out email to the mailing list when this discussion came in. Also there is an issue in the video buffer layer that results in an oops if buffer allocation fails. i.e if we request HD resolution buffer, then videobuf_reqbuf causes an oops somewhere in dma_contig buffer allocation. I have traced it to an dev_err() call. I was busy with my dm6467 capture port that I couldn't spend enough time root causing it. I have seen this issue in dm6467 display driver as well. So this is an urgent issue to be resolved soon in our drivers. >Regards, > > Hans > >> >> Murali Karicheri >> Software Design Engineer >> Texas Instruments Inc. >> Germantown, MD 20874 >> Phone : 301-515-3736 >> email: m-karicheri2@xxxxxx >> >>>-----Original Message----- >>>From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media- >>>owner@xxxxxxxxxxxxxxx] On Behalf Of Hans Verkuil >>>Sent: Thursday, July 30, 2009 10:26 AM >>>To: Karicheri, Muralidharan >>>Cc: Laurent Pinchart; Mauro Carvalho Chehab; Dongsoo, Nathaniel Kim; >>>v4l2_linux; Dongsoo Kim; 박경민; jm105.lee@xxxxxxxxxxx; >>>�세문; 대�기; 김ؕ준 >>>Subject: RE: How to save number of times using memcpy? >>> >>> >>>> Hans, >>>> >>>> I don't see the code you are referring to. Here is the probe() from the >>>> next branch of v4l-dvb. Could you point out the code that does the >>>> allocation of frame buffers ? I had used this code as reference when >>>> developing vpfe capture driver. >>>> >>>> Murali >>> >>>My apologies, I got it mixed up with older versions of this driver. I see >>>that it now uses videobuf-dma-contig. This is going to be a real problem >>>since this makes it impossible (or at least very hard) to allocate memory >>>up front. I'm no expert on videobuf, but this is something that should be >>>addressed, especially in the dma-contig case. >>> >>>Regards, >>> >>> Hans >>> >>>-- >>>Hans Verkuil - video4linux developer - sponsored by TANDBERG >>> >>>-- >>>To unsubscribe from this list: send the line "unsubscribe linux-media" in >>>the body of a message to majordomo@xxxxxxxxxxxxxxx >>>More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> >> > > >-- >Hans Verkuil - video4linux developer - sponsored by TANDBERG > >-- >To unsubscribe from this list: send the line "unsubscribe linux-media" in >the body of a message to majordomo@xxxxxxxxxxxxxxx >More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
