| Message ID | 00e201cd9069$4899d7a0$d9cd86e0$@com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Headers | show |
Hi David, On Wed 12 September 2012 00:03:32 David Oleszkiewicz wrote: > All, > I think I found a race condition with enabling interrupts in the > streamon call that I wanted some feedback on. I am actually using the > DaVinci PSP 03.03 GA Release (Build 37) kernel but I notice the same issue > in the current linux-davinci kernel that I just pulled down from > git://gitorious.org/linux-davinci/linux-davinci.git. I'll refer to the > latest linux-davinci code in for a discussion of the issue. At the end of > the vpif_streamon there is a call to vb2_streamon() which then invokes > vpif_start_streaming. At the end of vpif_start_streaming() the > channel_first_int[][] variable is set to 1 as a flag the ISR that the next > time it runs. However this line of code follows the code that enables the > interrupt. I was getting a race where the interrupt was enabled in > streamon(), then the ISR ran prior to the channel_first_int getting set. > This ended up hanging my user code in a Capture_get call. The problem crops > up randomly but frequently enough that it wasn't viable. > > I have just started looking into the vpif kernel code recently to > find out why my video input was hanging so I am not familiar with much of > the vpif cod, but it kind of made sense to reset the channel_first_int flag > that the interrupt handler queries prior to enabling the interrupts. I > moved that setting of the flag prior to setting the interrupts and it fixed > my issue. I made this change on my DaVinci PSP 03.03 GA Release (Build 37), > but look forward to testing with the freshest linux-davinci kernel. > Unfortunately it'll take some time to get my custom drivers for my video > chips ported over to that kernel. I agree with your analysis. The same problem is present in vpif_display.c as well. You are very unlucky as well with your timings to actually hit this race condition. Regards, Hans > Here's the diff: > > diff --git a/drivers/media/video/davinci/vpif_capture.c > b/drivers/media/video/davinci/vpif_capture.c > index 266025e..2e13d8b 100644 > --- a/drivers/media/video/davinci/vpif_capture.c > +++ b/drivers/media/video/davinci/vpif_capture.c > @@ -337,8 +337,10 @@ static int vpif_start_streaming(struct vb2_queue *vq, > unsigned int count) > > /** > * Set interrupt for both the fields in VPIF Register enable channel > in > - * VPIF register > + * VPIF register. First set the channel_first_int flag for the > interrupt > + * handler to pickup when it is asserted. > */ > + channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; > if ((VPIF_CHANNEL0_VIDEO == ch->channel_id)) { > channel0_intr_assert(); > channel0_intr_enable(1); > @@ -350,7 +352,6 @@ static int vpif_start_streaming(struct vb2_queue *vq, > unsigned int count) > channel1_intr_enable(1); > enable_channel1(1); > } > - channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; > > return 0; > } > > --- > David Oleszkiewicz > Adsys Controls, Inc. > 949-436-4848 > > This e-mail (including any attachments) is for the intended recipient. If > you are not an intended recipient or an authorized representative of an > intended recipient, you are prohibited from using, copying or distributing > the information in this e-mail or its attachments. If you have received this > e-mail in error, please notify the sender immediately by return e-mail and > delete all copies of this message and any attachments. > > > > _______________________________________________ > Davinci-linux-open-source mailing list > Davinci-linux-open-source@linux.davincidsp.com > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >
Hi David, Thanks for the findings :) On Wednesday 12 September 2012 03:05 PM, Hans Verkuil wrote: > Hi David, > > On Wed 12 September 2012 00:03:32 David Oleszkiewicz wrote: >> All, >> I think I found a race condition with enabling interrupts in the >> streamon call that I wanted some feedback on. I am actually using the >> DaVinci PSP 03.03 GA Release (Build 37) kernel but I notice the same issue >> in the current linux-davinci kernel that I just pulled down from >> git://gitorious.org/linux-davinci/linux-davinci.git. I'll refer to the >> latest linux-davinci code in for a discussion of the issue. At the end of >> the vpif_streamon there is a call to vb2_streamon() which then invokes >> vpif_start_streaming. At the end of vpif_start_streaming() the >> channel_first_int[][] variable is set to 1 as a flag the ISR that the next >> time it runs. However this line of code follows the code that enables the >> interrupt. I was getting a race where the interrupt was enabled in >> streamon(), then the ISR ran prior to the channel_first_int getting set. >> This ended up hanging my user code in a Capture_get call. The problem crops >> up randomly but frequently enough that it wasn't viable. >> >> I have just started looking into the vpif kernel code recently to >> find out why my video input was hanging so I am not familiar with much of >> the vpif cod, but it kind of made sense to reset the channel_first_int flag >> that the interrupt handler queries prior to enabling the interrupts. I >> moved that setting of the flag prior to setting the interrupts and it fixed >> my issue. I made this change on my DaVinci PSP 03.03 GA Release (Build 37), >> but look forward to testing with the freshest linux-davinci kernel. >> Unfortunately it'll take some time to get my custom drivers for my video >> chips ported over to that kernel. > > I agree with your analysis. The same problem is present in vpif_display.c as > well. > > You are very unlucky as well with your timings to actually hit this race > condition. > Can you submit a patch for this also making changes to display driver as pointed by Hans ? Note: The folder structure for video drivers is changed rebase the patch on this branch http://git.linuxtv.org/media_tree.git/shortlog/refs/heads/staging/for_v3.7 and make sure you CC the patches to media mailing list too (linux-kernel@vger.kernel.org). Regards, --Prabhakar > Regards, > > Hans > >> Here's the diff: >> >> diff --git a/drivers/media/video/davinci/vpif_capture.c >> b/drivers/media/video/davinci/vpif_capture.c >> index 266025e..2e13d8b 100644 >> --- a/drivers/media/video/davinci/vpif_capture.c >> +++ b/drivers/media/video/davinci/vpif_capture.c >> @@ -337,8 +337,10 @@ static int vpif_start_streaming(struct vb2_queue *vq, >> unsigned int count) >> >> /** >> * Set interrupt for both the fields in VPIF Register enable channel >> in >> - * VPIF register >> + * VPIF register. First set the channel_first_int flag for the >> interrupt >> + * handler to pickup when it is asserted. >> */ >> + channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; >> if ((VPIF_CHANNEL0_VIDEO == ch->channel_id)) { >> channel0_intr_assert(); >> channel0_intr_enable(1); >> @@ -350,7 +352,6 @@ static int vpif_start_streaming(struct vb2_queue *vq, >> unsigned int count) >> channel1_intr_enable(1); >> enable_channel1(1); >> } >> - channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; >> >> return 0; >> } >> >> --- >> David Oleszkiewicz >> Adsys Controls, Inc. >> 949-436-4848 >> >> This e-mail (including any attachments) is for the intended recipient. If >> you are not an intended recipient or an authorized representative of an >> intended recipient, you are prohibited from using, copying or distributing >> the information in this e-mail or its attachments. If you have received this >> e-mail in error, please notify the sender immediately by return e-mail and >> delete all copies of this message and any attachments. >> >> >> >> _______________________________________________ >> Davinci-linux-open-source mailing list >> Davinci-linux-open-source@linux.davincidsp.com >> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >> > _______________________________________________ > Davinci-linux-open-source mailing list > Davinci-linux-open-source@linux.davincidsp.com > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >
On Wed 12 September 2012 15:50:56 Prabhakar Lad wrote: > Hi David, > > Thanks for the findings :) > > On Wednesday 12 September 2012 03:05 PM, Hans Verkuil wrote: > > Hi David, > > > > On Wed 12 September 2012 00:03:32 David Oleszkiewicz wrote: > >> All, > >> I think I found a race condition with enabling interrupts in the > >> streamon call that I wanted some feedback on. I am actually using the > >> DaVinci PSP 03.03 GA Release (Build 37) kernel but I notice the same issue > >> in the current linux-davinci kernel that I just pulled down from > >> git://gitorious.org/linux-davinci/linux-davinci.git. I'll refer to the > >> latest linux-davinci code in for a discussion of the issue. At the end of > >> the vpif_streamon there is a call to vb2_streamon() which then invokes > >> vpif_start_streaming. At the end of vpif_start_streaming() the > >> channel_first_int[][] variable is set to 1 as a flag the ISR that the next > >> time it runs. However this line of code follows the code that enables the > >> interrupt. I was getting a race where the interrupt was enabled in > >> streamon(), then the ISR ran prior to the channel_first_int getting set. > >> This ended up hanging my user code in a Capture_get call. The problem crops > >> up randomly but frequently enough that it wasn't viable. > >> > >> I have just started looking into the vpif kernel code recently to > >> find out why my video input was hanging so I am not familiar with much of > >> the vpif cod, but it kind of made sense to reset the channel_first_int flag > >> that the interrupt handler queries prior to enabling the interrupts. I > >> moved that setting of the flag prior to setting the interrupts and it fixed > >> my issue. I made this change on my DaVinci PSP 03.03 GA Release (Build 37), > >> but look forward to testing with the freshest linux-davinci kernel. > >> Unfortunately it'll take some time to get my custom drivers for my video > >> chips ported over to that kernel. > > > > I agree with your analysis. The same problem is present in vpif_display.c as > > well. > > > > You are very unlucky as well with your timings to actually hit this race > > condition. > > > Can you submit a patch for this also making changes to display driver > as pointed by Hans ? > > Note: The folder structure for video drivers is changed rebase the patch > on this branch > http://git.linuxtv.org/media_tree.git/shortlog/refs/heads/staging/for_v3.7 > and make sure you CC the patches to media mailing list too > (linux-kernel@vger.kernel.org). That's linux-media@vger.kernel.org :-) Regards, Hans > > Regards, > --Prabhakar > > > > Regards, > > > > Hans > > > >> Here's the diff: > >> > >> diff --git a/drivers/media/video/davinci/vpif_capture.c > >> b/drivers/media/video/davinci/vpif_capture.c > >> index 266025e..2e13d8b 100644 > >> --- a/drivers/media/video/davinci/vpif_capture.c > >> +++ b/drivers/media/video/davinci/vpif_capture.c > >> @@ -337,8 +337,10 @@ static int vpif_start_streaming(struct vb2_queue *vq, > >> unsigned int count) > >> > >> /** > >> * Set interrupt for both the fields in VPIF Register enable channel > >> in > >> - * VPIF register > >> + * VPIF register. First set the channel_first_int flag for the > >> interrupt > >> + * handler to pickup when it is asserted. > >> */ > >> + channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; > >> if ((VPIF_CHANNEL0_VIDEO == ch->channel_id)) { > >> channel0_intr_assert(); > >> channel0_intr_enable(1); > >> @@ -350,7 +352,6 @@ static int vpif_start_streaming(struct vb2_queue *vq, > >> unsigned int count) > >> channel1_intr_enable(1); > >> enable_channel1(1); > >> } > >> - channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; > >> > >> return 0; > >> } > >> > >> --- > >> David Oleszkiewicz > >> Adsys Controls, Inc. > >> 949-436-4848 > >> > >> This e-mail (including any attachments) is for the intended recipient. If > >> you are not an intended recipient or an authorized representative of an > >> intended recipient, you are prohibited from using, copying or distributing > >> the information in this e-mail or its attachments. If you have received this > >> e-mail in error, please notify the sender immediately by return e-mail and > >> delete all copies of this message and any attachments. > >> > >> > >> > >> _______________________________________________ > >> Davinci-linux-open-source mailing list > >> Davinci-linux-open-source@linux.davincidsp.com > >> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source > >> > > _______________________________________________ > > Davinci-linux-open-source mailing list > > Davinci-linux-open-source@linux.davincidsp.com > > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source > > >
On Wednesday 12 September 2012 07:23 PM, Hans Verkuil wrote: > On Wed 12 September 2012 15:50:56 Prabhakar Lad wrote: >> Hi David, >> >> Thanks for the findings :) >> >> On Wednesday 12 September 2012 03:05 PM, Hans Verkuil wrote: >>> Hi David, >>> >>> On Wed 12 September 2012 00:03:32 David Oleszkiewicz wrote: >>>> All, >>>> I think I found a race condition with enabling interrupts in the >>>> streamon call that I wanted some feedback on. I am actually using the >>>> DaVinci PSP 03.03 GA Release (Build 37) kernel but I notice the same issue >>>> in the current linux-davinci kernel that I just pulled down from >>>> git://gitorious.org/linux-davinci/linux-davinci.git. I'll refer to the >>>> latest linux-davinci code in for a discussion of the issue. At the end of >>>> the vpif_streamon there is a call to vb2_streamon() which then invokes >>>> vpif_start_streaming. At the end of vpif_start_streaming() the >>>> channel_first_int[][] variable is set to 1 as a flag the ISR that the next >>>> time it runs. However this line of code follows the code that enables the >>>> interrupt. I was getting a race where the interrupt was enabled in >>>> streamon(), then the ISR ran prior to the channel_first_int getting set. >>>> This ended up hanging my user code in a Capture_get call. The problem crops >>>> up randomly but frequently enough that it wasn't viable. >>>> >>>> I have just started looking into the vpif kernel code recently to >>>> find out why my video input was hanging so I am not familiar with much of >>>> the vpif cod, but it kind of made sense to reset the channel_first_int flag >>>> that the interrupt handler queries prior to enabling the interrupts. I >>>> moved that setting of the flag prior to setting the interrupts and it fixed >>>> my issue. I made this change on my DaVinci PSP 03.03 GA Release (Build 37), >>>> but look forward to testing with the freshest linux-davinci kernel. >>>> Unfortunately it'll take some time to get my custom drivers for my video >>>> chips ported over to that kernel. >>> >>> I agree with your analysis. The same problem is present in vpif_display.c as >>> well. >>> >>> You are very unlucky as well with your timings to actually hit this race >>> condition. >>> >> Can you submit a patch for this also making changes to display driver >> as pointed by Hans ? >> >> Note: The folder structure for video drivers is changed rebase the patch >> on this branch >> http://git.linuxtv.org/media_tree.git/shortlog/refs/heads/staging/for_v3.7 >> and make sure you CC the patches to media mailing list too >> (linux-kernel@vger.kernel.org). > > That's linux-media@vger.kernel.org :-) > Oops copy paste error :), thanks for correcting. Thanks, --Prabhakar > Regards, > > Hans > >> >> Regards, >> --Prabhakar >> >> >>> Regards, >>> >>> Hans >>> >>>> Here's the diff: >>>> >>>> diff --git a/drivers/media/video/davinci/vpif_capture.c >>>> b/drivers/media/video/davinci/vpif_capture.c >>>> index 266025e..2e13d8b 100644 >>>> --- a/drivers/media/video/davinci/vpif_capture.c >>>> +++ b/drivers/media/video/davinci/vpif_capture.c >>>> @@ -337,8 +337,10 @@ static int vpif_start_streaming(struct vb2_queue *vq, >>>> unsigned int count) >>>> >>>> /** >>>> * Set interrupt for both the fields in VPIF Register enable channel >>>> in >>>> - * VPIF register >>>> + * VPIF register. First set the channel_first_int flag for the >>>> interrupt >>>> + * handler to pickup when it is asserted. >>>> */ >>>> + channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; >>>> if ((VPIF_CHANNEL0_VIDEO == ch->channel_id)) { >>>> channel0_intr_assert(); >>>> channel0_intr_enable(1); >>>> @@ -350,7 +352,6 @@ static int vpif_start_streaming(struct vb2_queue *vq, >>>> unsigned int count) >>>> channel1_intr_enable(1); >>>> enable_channel1(1); >>>> } >>>> - channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; >>>> >>>> return 0; >>>> } >>>> >>>> --- >>>> David Oleszkiewicz >>>> Adsys Controls, Inc. >>>> 949-436-4848 >>>> >>>> This e-mail (including any attachments) is for the intended recipient. If >>>> you are not an intended recipient or an authorized representative of an >>>> intended recipient, you are prohibited from using, copying or distributing >>>> the information in this e-mail or its attachments. If you have received this >>>> e-mail in error, please notify the sender immediately by return e-mail and >>>> delete all copies of this message and any attachments. >>>> >>>> >>>> >>>> _______________________________________________ >>>> Davinci-linux-open-source mailing list >>>> Davinci-linux-open-source@linux.davincidsp.com >>>> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >>>> >>> _______________________________________________ >>> Davinci-linux-open-source mailing list >>> Davinci-linux-open-source@linux.davincidsp.com >>> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >>> >>
Hi David, On Wed, Sep 12, 2012 at 7:30 PM, Prabhakar Lad <prabhakar.lad@ti.com> wrote: > On Wednesday 12 September 2012 07:23 PM, Hans Verkuil wrote: >> On Wed 12 September 2012 15:50:56 Prabhakar Lad wrote: >>> Hi David, >>> >>> Thanks for the findings :) >>> >>> On Wednesday 12 September 2012 03:05 PM, Hans Verkuil wrote: >>>> Hi David, >>>> >>>> On Wed 12 September 2012 00:03:32 David Oleszkiewicz wrote: >>>>> All, >>>>> I think I found a race condition with enabling interrupts in the >>>>> streamon call that I wanted some feedback on. I am actually using the >>>>> DaVinci PSP 03.03 GA Release (Build 37) kernel but I notice the same issue >>>>> in the current linux-davinci kernel that I just pulled down from >>>>> git://gitorious.org/linux-davinci/linux-davinci.git. I'll refer to the >>>>> latest linux-davinci code in for a discussion of the issue. At the end of >>>>> the vpif_streamon there is a call to vb2_streamon() which then invokes >>>>> vpif_start_streaming. At the end of vpif_start_streaming() the >>>>> channel_first_int[][] variable is set to 1 as a flag the ISR that the next >>>>> time it runs. However this line of code follows the code that enables the >>>>> interrupt. I was getting a race where the interrupt was enabled in >>>>> streamon(), then the ISR ran prior to the channel_first_int getting set. >>>>> This ended up hanging my user code in a Capture_get call. The problem crops >>>>> up randomly but frequently enough that it wasn't viable. >>>>> >>>>> I have just started looking into the vpif kernel code recently to >>>>> find out why my video input was hanging so I am not familiar with much of >>>>> the vpif cod, but it kind of made sense to reset the channel_first_int flag >>>>> that the interrupt handler queries prior to enabling the interrupts. I >>>>> moved that setting of the flag prior to setting the interrupts and it fixed >>>>> my issue. I made this change on my DaVinci PSP 03.03 GA Release (Build 37), >>>>> but look forward to testing with the freshest linux-davinci kernel. >>>>> Unfortunately it'll take some time to get my custom drivers for my video >>>>> chips ported over to that kernel. >>>> >>>> I agree with your analysis. The same problem is present in vpif_display.c as >>>> well. >>>> >>>> You are very unlucky as well with your timings to actually hit this race >>>> condition. >>>> >>> Can you submit a patch for this also making changes to display driver >>> as pointed by Hans ? >>> >>> Note: The folder structure for video drivers is changed rebase the patch >>> on this branch >>> http://git.linuxtv.org/media_tree.git/shortlog/refs/heads/staging/for_v3.7 >>> and make sure you CC the patches to media mailing list too >>> (linux-kernel@vger.kernel.org). >> >> That's linux-media@vger.kernel.org :-) >> I have posted the patch fixing this issue http://patchwork.linuxtv.org/patch/14418/ Regards, --Prabhakar Lad > Oops copy paste error :), thanks for correcting. > > Thanks, > --Prabhakar > >> Regards, >> >> Hans >> >>> >>> Regards, >>> --Prabhakar >>> >>> >>>> Regards, >>>> >>>> Hans >>>> >>>>> Here's the diff: >>>>> >>>>> diff --git a/drivers/media/video/davinci/vpif_capture.c >>>>> b/drivers/media/video/davinci/vpif_capture.c >>>>> index 266025e..2e13d8b 100644 >>>>> --- a/drivers/media/video/davinci/vpif_capture.c >>>>> +++ b/drivers/media/video/davinci/vpif_capture.c >>>>> @@ -337,8 +337,10 @@ static int vpif_start_streaming(struct vb2_queue *vq, >>>>> unsigned int count) >>>>> >>>>> /** >>>>> * Set interrupt for both the fields in VPIF Register enable channel >>>>> in >>>>> - * VPIF register >>>>> + * VPIF register. First set the channel_first_int flag for the >>>>> interrupt >>>>> + * handler to pickup when it is asserted. >>>>> */ >>>>> + channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; >>>>> if ((VPIF_CHANNEL0_VIDEO == ch->channel_id)) { >>>>> channel0_intr_assert(); >>>>> channel0_intr_enable(1); >>>>> @@ -350,7 +352,6 @@ static int vpif_start_streaming(struct vb2_queue *vq, >>>>> unsigned int count) >>>>> channel1_intr_enable(1); >>>>> enable_channel1(1); >>>>> } >>>>> - channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; >>>>> >>>>> return 0; >>>>> } >>>>> >>>>> --- >>>>> David Oleszkiewicz >>>>> Adsys Controls, Inc. >>>>> 949-436-4848 >>>>> >>>>> This e-mail (including any attachments) is for the intended recipient. If >>>>> you are not an intended recipient or an authorized representative of an >>>>> intended recipient, you are prohibited from using, copying or distributing >>>>> the information in this e-mail or its attachments. If you have received this >>>>> e-mail in error, please notify the sender immediately by return e-mail and >>>>> delete all copies of this message and any attachments. >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Davinci-linux-open-source mailing list >>>>> Davinci-linux-open-source@linux.davincidsp.com >>>>> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >>>>> >>>> _______________________________________________ >>>> Davinci-linux-open-source mailing list >>>> Davinci-linux-open-source@linux.davincidsp.com >>>> http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source >>>> >>> > > _______________________________________________ > Davinci-linux-open-source mailing list > Davinci-linux-open-source@linux.davincidsp.com > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
diff --git a/drivers/media/video/davinci/vpif_capture.c b/drivers/media/video/davinci/vpif_capture.c index 266025e..2e13d8b 100644 --- a/drivers/media/video/davinci/vpif_capture.c +++ b/drivers/media/video/davinci/vpif_capture.c @@ -337,8 +337,10 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count) /** * Set interrupt for both the fields in VPIF Register enable channel in - * VPIF register + * VPIF register. First set the channel_first_int flag for the interrupt + * handler to pickup when it is asserted. */ + channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1;
All, I think I found a race condition with enabling interrupts in the streamon call that I wanted some feedback on. I am actually using the DaVinci PSP 03.03 GA Release (Build 37) kernel but I notice the same issue in the current linux-davinci kernel that I just pulled down from git://gitorious.org/linux-davinci/linux-davinci.git. I'll refer to the latest linux-davinci code in for a discussion of the issue. At the end of the vpif_streamon there is a call to vb2_streamon() which then invokes vpif_start_streaming. At the end of vpif_start_streaming() the channel_first_int[][] variable is set to 1 as a flag the ISR that the next time it runs. However this line of code follows the code that enables the interrupt. I was getting a race where the interrupt was enabled in streamon(), then the ISR ran prior to the channel_first_int getting set. This ended up hanging my user code in a Capture_get call. The problem crops up randomly but frequently enough that it wasn't viable. I have just started looking into the vpif kernel code recently to find out why my video input was hanging so I am not familiar with much of the vpif cod, but it kind of made sense to reset the channel_first_int flag that the interrupt handler queries prior to enabling the interrupts. I moved that setting of the flag prior to setting the interrupts and it fixed my issue. I made this change on my DaVinci PSP 03.03 GA Release (Build 37), but look forward to testing with the freshest linux-davinci kernel. Unfortunately it'll take some time to get my custom drivers for my video chips ported over to that kernel. Here's the diff: if ((VPIF_CHANNEL0_VIDEO == ch->channel_id)) { channel0_intr_assert(); channel0_intr_enable(1); @@ -350,7 +352,6 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count) channel1_intr_enable(1); enable_channel1(1); } - channel_first_int[VPIF_VIDEO_INDEX][ch->channel_id] = 1; return 0; } --- David Oleszkiewicz Adsys Controls, Inc. 949-436-4848 This e-mail (including any attachments) is for the intended recipient. If you are not an intended recipient or an authorized representative of an intended recipient, you are prohibited from using, copying or distributing the information in this e-mail or its attachments. If you have received this e-mail in error, please notify the sender immediately by return e-mail and delete all copies of this message and any attachments.