> -----Original Message-----
> From: Cousson, Benoit
> Sent: Wednesday, August 04, 2010 3:38 PM
> To: G, Manjunath Kondaiah
> Cc: Kevin Hilman; linux-omap@vger.kernel.org; Paul Walmsley; Tony
> Lindgren; Sawant, Anand; Shilimkar, Santosh; Nayak, Rajendra; Basak,
> Partha; Varadarajan, Charulatha
> Subject: Re: [PATCH 04/11] OMAP3: DMA: HWMOD: Add hwmod data structures
>
> On 8/4/2010 2:35 AM, G, Manjunath Kondaiah wrote:
> > Kevin,
> >
> >> From: Kevin Hilman [mailto:khil...@deeprootsystems.com]
> >> Sent: Wednesday, August 04, 2010 3:27 AM
> >>
> >> Manjunatha GK<manj...@ti.com> writes:
> >>
> >>> This patch adds OMAP3 DMA hwmod structures.
> >>>
> >>> Signed-off-by: Manjunatha GK<manj...@ti.com>
> >>
> >> [...]
> >>
> >>> +static struct omap_hwmod omap3xxx_dma_system_hwmod = {
> >>> + .name = "dma",
> >>> + .class =&omap3xxx_dma_hwmod_class,
> >>> + .mpu_irqs = omap3xxx_dma_system_irqs,
> >>> + .mpu_irqs_cnt = ARRAY_SIZE(omap3xxx_dma_system_irqs),
> >>> + .main_clk = "l3_div_ck",
> >>> + .prcm = {
> >>> + .omap2 = {
> >>> + /* .clkctrl_reg = NULL, */
> >>> + },
> >>> + },
> >>
> >> Has this been tested? Without valid fields here the hwmod
> >> will never be
> >> enabled.
> >
> > This patch series has been tested on both omap3 and omap4. I didn't find
> > any entries for DMA module in prcm-common.h(for assigning .module_bit
> etc)
> > hence I commented this for clarification.
>
> There is no explicit PRCM control for the SDMA. You can just access the
> standby status and change the sysconfig idle and standby settings.
> It uses the L3 interface clock as functional clock.
> You should still use HWMOD_NO_IDLEST status to prevent the enable to
> crash.
>
> In your case, I think that you are probably never explicitly enabling or
> disabling the dma device due to the library kind of API and the fact
> that the HW is managing is automatically, isn't it?
>
> We had the same kind of discussion for the hwspinlock. Since these IPs
> are using interface clock as a functional clock, there is no need to
> explicitly enable them. But we should, otherwise we have no way to track
> the usage of this IP and potentially to enable the power domain that
> contains these IP.
>
> Each time a dma channel is requested, you should call the
> pm_runtime_get, and pm_runtime_put() when the channel is not needed
> anymore.
>
Request call can get called on multiple channels.
So at the time of request a channel, other channels might be already
in use. So logically " pm_runtime_put" should only be done if
reserved channels are 0
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