linux-kernel - Re: [RFC PATCH v2 05/13] clk: bd718x7: Support ROHM BD71828 clk block

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Message-ID: <95b21eeaee8025dc430623429273116c35c1b769.camel@fi.rohmeurope.com>
Date:   Tue, 29 Oct 2019 06:28:51 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "mazziesaccount@...il.com" <mazziesaccount@...il.com>,
        "sboyd@...nel.org" <sboyd@...nel.org>
CC:     "dmurphy@...com" <dmurphy@...com>,
        "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "jacek.anaszewski@...il.com" <jacek.anaszewski@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "bgolaszewski@...libre.com" <bgolaszewski@...libre.com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "pavel@....cz" <pavel@....cz>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "broonie@...nel.org" <broonie@...nel.org>
Subject: Re: [RFC PATCH v2 05/13] clk: bd718x7: Support ROHM BD71828 clk
 block

Hello Stephen,

Thanks for the comments once again :)

On Mon, 2019-10-28 at 16:32 -0700, Stephen Boyd wrote:
> Quoting Matti Vaittinen (2019-10-24 04:44:40)
> > diff --git a/drivers/clk/clk-bd718x7.c b/drivers/clk/clk-bd718x7.c
> > index ae6e5baee330..d17a19e04592 100644
> > --- a/drivers/clk/clk-bd718x7.c
> > +++ b/drivers/clk/clk-bd718x7.c
> > @@ -8,6 +8,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/slab.h>
> >  #include <linux/mfd/rohm-bd718x7.h>
> > +#include <linux/mfd/rohm-bd71828.h>
> >  #include <linux/mfd/rohm-bd70528.h>
> 
> It would be really great to not need to include these random header
> files in this driver and just use raw numbers somehow. Looks like
> maybe
> it can be done by populating a different device name from the mfd
> driver
> depending on the version of the clk controller desired? Then that can
> be
> matched in this clk driver and we can just put the register info in
> this
> file?

I still like keeping the chip type information on one header - no
matter what-ever format the clk-controller type/version information is.
Rationale is that MFD and also few other sub-devices (not only the clk)
need to use it. Currently at least the RTC.

But if we define clk register information for all PMICs in this c-file, 
then (I think) we can only include the <linux/mfd/rohm-generic.h> -
which contains the PMIC type defines and the generic MFD data
structure. That would:

-#include <linux/mfd/rohm-bd718x7.h>
-#include <linux/mfd/rohm-bd71828.h>
-#include <linux/mfd/rohm-bd70528.h>
+#include <linux/mfd/rohm-generic.h>

That way the chip-type information could still be same for MFD and all
sub-devices but clk driver would not need to include all the details
for all the PMICs. I understand your point well as clk registers for
these PMICs are really *limited*.

> 
> >  #include <linux/clk-provider.h>
> >  #include <linux/clkdev.h>
> > @@ -21,10 +22,8 @@ struct bd718xx_clk {
> >         struct rohm_regmap_dev *mfd;
> >  };
> >  
> > -static int bd71837_clk_set(struct clk_hw *hw, int status)
> > +static int bd71837_clk_set(struct bd718xx_clk *c, int status)
> 
> should it be unsigned int status? Or maybe u32?
> 
> >  {
> > -       struct bd718xx_clk *c = container_of(hw, struct
> > bd718xx_clk, hw);
> > -
> >         return regmap_update_bits(c->mfd->regmap, c->reg, c->mask,
> > status);
> >  }
> >  
> > @@ -33,14 +32,16 @@ static void bd71837_clk_disable(struct clk_hw
> > *hw)
> >         int rv;
> >         struct bd718xx_clk *c = container_of(hw, struct
> > bd718xx_clk, hw);
> >  
> > -       rv = bd71837_clk_set(hw, 0);
> > +       rv = bd71837_clk_set(c, 0);
> >         if (rv)
> >                 dev_dbg(&c->pdev->dev, "Failed to disable 32K clk
> > (%d)\n", rv);
> >  }
> >  
> >  static int bd71837_clk_enable(struct clk_hw *hw)
> >  {
> > -       return bd71837_clk_set(hw, 1);
> > +       struct bd718xx_clk *c = container_of(hw, struct
> > bd718xx_clk, hw);
> > +
> > +       return bd71837_clk_set(c, 0xffffffff);
> 
> Because now this is passing -1 to unsigned int taking
> regmap_update_bits()?

I think that bit-wise it is all the same. Currently registers are only
8bits wide so it is enough that lowest 8 bits are set. And 0xffffffff
should work nicely up-to 32bit registers as long as int is 32 bit or
more.

But you are correct that this is not looking good. At first sight
unsigned int is much nicer. I prefer unsigned int over forced u32 to
guarantee natural alignment - which does not really matter in this case
either. unsigned int matches regmap though so I'll switch to it. Thanks
for pointing this out :)

I'll try to include these clk changes in v3.


Br,
	Matti Vaittinen