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Groups > linux.kernel > #1538489
| From | Geert Uytterhoeven <geert@linux-m68k.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: Tearing down DMA transfer setup after DMA client has finished |
| Date | 2016-12-08 13:40 +0100 |
| Message-ID | <sM69r-68W-11@gated-at.bofh.it> (permalink) |
| References | (8 earlier) <sLNzQ-2yE-21@gated-at.bofh.it> <sM4hj-51v-15@gated-at.bofh.it> <sM5n3-5Di-3@gated-at.bofh.it> <sM5Gq-5YO-27@gated-at.bofh.it> <sM5ZM-65C-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Dec 8, 2016 at 1:20 PM, Måns Rullgård <mans@mansr.com> wrote:
> Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> On Thu, Dec 8, 2016 at 12:44 PM, Måns Rullgård <mans@mansr.com> wrote:
>>> Vinod Koul <vinod.koul@intel.com> writes:
>>>> On Wed, Dec 07, 2016 at 04:45:58PM +0000, Måns Rullgård wrote:
>>>>> Vinod Koul <vinod.koul@intel.com> writes:
>>>>> > On Tue, Dec 06, 2016 at 01:14:20PM +0000, Måns Rullgård wrote:
>>>>> >> That's not going to work very well. Device drivers typically request
>>>>> >> dma channels in their probe functions or when the device is opened.
>>>>> >> This means that reserving one of the few channels there will inevitably
>>>>> >> make some other device fail to operate.
>>>>> >
>>>>> > No that doesnt make sense at all, you should get a channel only when you
>>>>> > want to use it and not in probe!
>>>>>
>>>>> Tell that to just about every single driver ever written.
>>>>
>>>> Not really, few do yes which is wrong but not _all_ do that.
>>>
>>> Every driver I ever looked at does. Name one you consider "correct."
>>
>> I'm far from claiming that drivers/tty/serial/sh-sci.c is perfect, but
>> it does request DMA channels at open time, not at probe time.
>
> In the part quoted above, I said most drivers request dma channels in
> their probe or open functions. For the purposes of this discussion,
> that distinction is irrelevant. In either case, the channel is held
> indefinitely. If this wasn't the correct way to use the dmaengine,
> there would be no need for the virt-dma helpers which are specifically
> designed for cases the one currently at hand.
Sorry, I mainly read Vinod's "not in probe", and missed your "or when the
device is opened".
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-11-25 13:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-11-25 14:20 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-11-25 15:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-11-25 15:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-11-25 16:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-11-29 19:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-06 06:10 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-06 13:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-06 14:20 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-06 16:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-06 16:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-07 00:00 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-07 17:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-07 17:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-08 11:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-08 12:00 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 12:20 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 12:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 13:10 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-08 13:20 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 13:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-08 17:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 17:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-09 08:10 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Sebastian Frias <sf84@laposte.net> - 2016-12-09 11:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-09 12:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished 1Måns Rullgård <mans@mansr.com> - 2016-12-09 12:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-09 18:20 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-09 18:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-09 19:00 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-09 18:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-09 19:00 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-09 19:20 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-09 19:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 12:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 13:10 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 13:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Geert Uytterhoeven <geert@linux-m68k.org> - 2016-12-08 13:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 13:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-08 14:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 14:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-08 13:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-08 16:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 17:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-08 16:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Mason <slash.tmp@free.fr> - 2016-12-08 16:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-08 17:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 17:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-07 17:40 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-07 17:50 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Vinod Koul <vinod.koul@intel.com> - 2016-12-08 11:30 +0100
Re: Tearing down DMA transfer setup after DMA client has finished Måns Rullgård <mans@mansr.com> - 2016-12-08 12:50 +0100
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