[Nouveau] Interrupt setting

[Shinpei KATO]

Dear Younes,

Thank you for your reply.

> Nouveau doesn't really make use of interrupts so you wont see them
> while running OpenGL. In general we make use of fences to signal when
> things of interest have occured. Is there something particular you're
> trying to accomplish or is this just a learning exercise?

I have been using Nouveau for a research purpose, though it has been just a
month.
So I can say both something particular and a learning exercise.
I have tried understanding the behavir of fences, but a bit hard to catch up
the execution flow.

To my understanding, for instance every time pushbuf ioctl is called, you
create a fence object.
Does this make a caller process to wait for a completion of a GPU command?
I inserted printk()s in nouveau_fence_wait(), but the process does not seem
sleeping.

I am also wondering if current GPUs can be set up to generate interrupts
when GPU commands are done.
My guess is that NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY is to generate interrupts
when DMA transfers are done.
Am I misunderstanding?

Best,
- Shinpei

> -----Original Message-----
> From: Younes Manton [mailto:younes.m at gmail.com]
> Sent: Saturday, March 13, 2010 10:31 AM
> To: Shinpei KATO
> Cc: nouveau at lists.freedesktop.org
> Subject: Re: [Nouveau] Interrupt setting
> 
> On Fri, Mar 12, 2010 at 4:14 PM, Shinpei KATO
> <shinpei at il.is.s.u-tokyo.ac.jp> wrote:
> > Hi,
> >
> > I am responding to myself...
> > Interrupts now work; I should have set the
> > NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY_STYLE_WRITE_LE_AWAKEN flag every
> time a
> > command is sent.
> > In fact, I thought this flag tells GPU to notify us of when DMA
transfers
> > are done, but I got PGRAPH_NOTIFY interrupts by this.
> > It sounds to me that they notify of when GPU operations are done rather
> than
> > DMA transfers.
> > # PGRAPH_BUFFER_NOTIFY sounds more related to DMA transfers.
> >
> > Is my understanding wrong?
> > I appreciate any comments or information about this.
> >
> > Best regards,
> > - Shinpei
> >
> >> -----Original Message-----
> >> From: nouveau-bounces at lists.freedesktop.org
> >> [mailto:nouveau-bounces at lists.freedesktop.org] On Behalf Of Shinpei
> KATO
> >> Sent: Friday, March 12, 2010 7:21 AM
> >> To: nouveau at lists.freedesktop.org
> >> Subject: [Nouveau] Interrupt setting
> >>
> >> Hi all,
> >>
> >> I am a Nouveau user on FC12 with GeForce 9500GT.
> >> I have read the Nouveau wiki documents, and they imply that there are
> ways
> >> to set GPU to send interrupts to CPU, when we want to be notified for
> >> something, e.g., when DMA transfer or GPU operation is completed.
> >> By default, when I run an OpenGL demo application from Gallium3D, the
> > driver
> >> gets no interrupts from GPU in nouveau_irq_handler(), except that it
> gets
> >> one NV_PFIFO_INTR_CACHE_ERROR interrupt right after the FIFO is
> allocated.
> >> According to the wiki docs, I need to set
> >> NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY_STYLE_WRITE_LE_AWAKEN into the
> >> 'notify'
> >> field of an object in a channel.
> >> Hence, I tried seting a flag to a DMA notifier in nouveau_dma_init():
> >>
> >> // seems entry[1] is related to a DMA notifier?
> >> nv_wo32(dev, m2mf, 1,
> >> NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY_STYLE_WRITE_LE_AWAKEN);
> >>
> >> I also tried sending some command:
> >>
> >> // guess this is a very wrong way ;-)
> >> BEGIN_RING(chan, NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY, 1);
> >> OUT_RING(chan,
> >> NV_MEMORY_TO_MEMORY_FORMAT_NOTIFY_STYLE_WRITE_LE_AWAKEN);
> >>
> >> But they both did not work...
> >> How can we set GPU to send interrupts to CPU?
> >> I would appreciate your comments.
> >>
> >> Thanks,
> >> - Shinpei
> >>
> 
> Nouveau doesn't really make use of interrupts so you wont see them
> while running OpenGL. In general we make use of fences to signal when
> things of interest have occured. Is there something particular you're
> trying to accomplish or is this just a learning exercise?