linux-kernel - Re: [PATCH v2 03/10] clk: sunxi: Let divs clocks read the base factor clock name from devicetree

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Message-ID: <20150519082635.GW4004@lukather>
Date:	Tue, 19 May 2015 10:26:35 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Jens Kuske <jenskuske@...il.com>
Cc:	Emilio López <emilio@...pez.com.ar>,
	Mike Turquette <mturquette@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
	Vishnu Patekar <vishnupatekar0510@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 03/10] clk: sunxi: Let divs clocks read the base
 factor clock name from devicetree

On Mon, May 18, 2015 at 11:22:32AM +0200, Jens Kuske wrote:
> On 05/17/15 15:06, Maxime Ripard wrote:
> > On Fri, May 15, 2015 at 06:38:53PM +0200, Jens Kuske wrote:
> >> Currently, the sunxi clock driver gets the name for the base factor clock
> >> of divs clocks from the name field in factors_data. This prevents reusing
> >> of the factor clock for clocks with same properties, but different name.
> >>
> >> This commit makes the divs setup function try to get a name from
> >> clock-output-names in the devicetree. It also removes the name field where
> >> possible and merges the sun4i PLL5 and PLL6 clocks.
> >>
> >> The sun4i PLL5 clock doesn't have a output for the base factor clock,
> >> so we still have to use the name field there.
> >>
> >> Signed-off-by: Jens Kuske <jenskuske@...il.com>
> >> ---
> >>  drivers/clk/sunxi/clk-sunxi.c | 22 ++++++++++++----------
> >>  1 file changed, 12 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
> >> index 17cba4d..afe560c 100644
> >> --- a/drivers/clk/sunxi/clk-sunxi.c
> >> +++ b/drivers/clk/sunxi/clk-sunxi.c
> >> @@ -708,18 +708,10 @@ static const struct factors_data sun4i_pll5_data __initconst = {
> >>  	.name = "pll5",
> >>  };
> >>  
> >> -static const struct factors_data sun4i_pll6_data __initconst = {
> >> -	.enable = 31,
> >> -	.table = &sun4i_pll5_config,
> >> -	.getter = sun4i_get_pll5_factors,
> >> -	.name = "pll6",
> >> -};
> >> -
> >>  static const struct factors_data sun6i_a31_pll6_data __initconst = {
> >>  	.enable = 31,
> >>  	.table = &sun6i_a31_pll6_config,
> >>  	.getter = sun6i_a31_get_pll6_factors,
> >> -	.name = "pll6x2",
> >>  };
> >>  
> >>  static const struct factors_data sun5i_a13_ahb_data __initconst = {
> >> @@ -1099,7 +1091,7 @@ static const struct divs_data pll5_divs_data __initconst = {
> >>  };
> >>  
> >>  static const struct divs_data pll6_divs_data __initconst = {
> >> -	.factors = &sun4i_pll6_data,
> >> +	.factors = &sun4i_pll5_data,
> >>  	.ndivs = 4,
> >>  	.div = {
> >>  		{ .shift = 0, .table = pll6_sata_tbl, .gate = 14 }, /* M, SATA */
> >> @@ -1141,6 +1133,7 @@ static void __init sunxi_divs_clk_setup(struct device_node *node,
> >>  	struct clk_gate *gate = NULL;
> >>  	struct clk_fixed_factor *fix_factor;
> >>  	struct clk_divider *divider;
> >> +	struct factors_data factors = *data->factors;
> >>  	void __iomem *reg;
> >>  	int ndivs = SUNXI_DIVS_MAX_QTY, i = 0;
> >>  	int flags, clkflags;
> >> @@ -1149,8 +1142,17 @@ static void __init sunxi_divs_clk_setup(struct device_node *node,
> >>  	if (data->ndivs)
> >>  		ndivs = data->ndivs;
> >>  
> >> +	/* Try to find a name for base factor clock */
> >> +	for (i = 0; i < ndivs; i++) {
> >> +		if (data->div[i].self) {
> > 
> > I'm not sure we should expect the factor clock to have a self factor.
> 
> Maybe not, but in that case it would fall back to the name provided in
> the factors_data struct, as it is the case for sun4i pll5.

Which doesn't really solve the underlying issue, just make it work in
your (pll6/pll8) case.
 
> > what about taking the first output and taking the substring up to the
> > first "_" ?
> 
> That only works for the sun[457]i pll5 & pll6, for sun[68]i the base
> clock name would have to be "pll6x2".

Why?

It's called pll6 in the datasheet, it should really be called
pll6. The fact that there is some fixed factors or dividers on some
children only impacts those children, and not the system as a whole.

And the fact that the "base" clock is pll6x2 and not pll6 itself is
very debatable. How do you know which clock is the base one? Most
clocks are actually using pll6 as a reference.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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