[alsa-devel] [PATCH] OMAP: Exporting functions doing common register access

[Paul Walmsley]

Hello Anuj,

On Thu, 7 Jan 2010, Aggarwal, Anuj wrote:

> > > > In the interim, I would suggest that you remove the the clock source
> > and
> > > > receiver source change functions from omap-mcbsp.c, split them into
> > OMAP1
> > > > and OMAP2/3 variants, and place them into arch/arm/mach-omap*/mcbsp.c.
> > > > Expand struct omap_mcbsp_ops to add function pointers to those
> > functions.
> > > > Call those from soc/omap-mcbsp.c via mcbsp->pdata->ops. That way you
> > won't
> > > > need those exports.
> > > >
> > > Paul: What's your opinnion, would it be possible or would it be wise to
> > > handle these McBSP clock route setups with the clock framework instead?
> > >
> > > Functions omap_mcbsp_dai_set_clks_src and omap_mcbsp_dai_set_rcvr_src
> > > are basically just setting up the input clock for McBSP SRG or McBSP1
> > > receiver.
> > 
> > Sure.  There already should be some support for it in clock34xx.h, but I
> > doubt anyone's tested it:
> > 
> > static struct clk mcbsp1_fck = {
> >         .name           = "mcbsp_fck",
> >         .ops            = &clkops_omap2_dflt_wait,
> >         .id             = 1,
> >         .init           = &omap2_init_clksel_parent,
> >         .enable_reg     = OMAP_CM_REGADDR(CORE_MOD, CM_FCLKEN1),
> >         .enable_bit     = OMAP3430_EN_MCBSP1_SHIFT,
> >         .clksel_reg     = OMAP343X_CTRL_REGADDR(OMAP2_CONTROL_DEVCONF0),
> >         .clksel_mask    = OMAP2_MCBSP1_CLKS_MASK,
> >         .clksel         = mcbsp_15_clksel,
> >         .clkdm_name     = "core_l4_clkdm",
> >         .recalc         = &omap2_clksel_recalc,
> > };
> > 
> > etc.  Some similar entries would need to be added to the clock24xx.h file.
> [Aggarwal, Anuj] One problem which I found in trying the above discussed 
> approach is that I am not able to get mcbsp clock handles in omap-mcbsp.c 
> file. 

Why not?  Looks like there are init and exit functions in there.  Those 
would seem like logical places for clk_get()/clk_put().

> To call clk_set_parent() with the new parent clock as "mcbsp_clks" 
> (in case of an external clock), I need the mcbsp_fck clock handle. But this
> handle is not shared with the omap_mcbsp_dai[].

Have you considered static variable(s)?

> What should be the right method of getting this handle in 
> omap_mcbsp_dai_set_dai_sysclk(), in case I understood the concept properly.
> Basically, we want to get rid of the low level stuff in this function 
> and instead use standard clock framework APIs?

Yep, the contents of both the omap_mcbsp_dai_set_clks_src() function and 
the omap_mcbsp_dai_set_rcvr_src() should be implementable with standard 
clock framework APIs.


- Paul