[PATCH/RFC] ARM: shmobile: r8a7794: Add Audio DMAC, PWM and Thermal clocks to device tree
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Mon Jan 5 12:59:15 PST 2015
Hi Geert,
On Monday 05 January 2015 09:52:37 Geert Uytterhoeven wrote:
> On Mon, Jan 5, 2015 at 9:30 AM, Laurent Pinchart wrote:
> > On Friday 19 December 2014 09:39:33 Simon Horman wrote:
> >> This is based on the MSTP5 clocks in the r8a7791 device tree.
> >> The main difference being that the r8a7794 does not have an Audio DMAC1
> >> clock.
> >>
> >> Signed-off-by: Simon Horman <horms+renesas at verge.net.au>
> >>
> >> ---
> >> Based on the renesas-devel-20141217-v3.18 tag of my renesas tree.
> >>
> >> N.B: The R-Car Gen2 v1.8.0 BSP uses zs_clk whereas this patch uses hp_clk
> >> as the parent clock for the Audio DMAC clock.
> >>
> >> In that regard this patch follows the pattern used in mainline for
> >> the r8a7790 and r8a7791 SoCs.
> >>
> >> The BSP's parent clock is consistent for the r8a7790, r8a7791,
> >> r8a7793 and r8a7794 SoCs.
> >
> > Does this mean the BSP uses hp_clk for all Gen2 SoCs while mainline uses
> > zs_clk ?
>
> No, it's the other way around ;-)
Sorry, that's what I meant.
> > Can't we find out which one is correct ?
>
> Which clock is used doesn't seem to be documented.
> So either we have to check with the hardware guys, or measure the clock
> in some way, either by hardware or software (e.g. what's the maximum
> transfer rate that works?).
Given the parent clock frequencies (130 MHz and 260 MHz) and the audio rates,
I'm not sure any useful measurement could be performed.
--
Regards,
Laurent Pinchart
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