linux-kernel - Re: [PATCH 1/2] clk: qcom: clk-rpmh: Add QCOM RPMh clock driver

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Date:   Tue, 10 Apr 2018 17:05:23 +0000
From:   Evan Green <evgreen@...omium.org>
To:     sboyd@...nel.org
Cc:     tdas@...eaurora.org, sboyd@...eaurora.org,
        Michael Turquette <mturquette@...libre.com>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        okukatla@...eaurora.org, anischal@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        collinsd@...eaurora.org
Subject: Re: [PATCH 1/2] clk: qcom: clk-rpmh: Add QCOM RPMh clock driver

On Thu, Apr 5, 2018 at 4:17 PM Stephen Boyd <sboyd@...nel.org> wrote:

> Quoting Taniya Das (2018-04-02 03:33:26)
> >
> > >
> > >> +
> > >> +#include "common.h"
> > >> +#include "clk-regmap.h"
> > >> +
> > >> +#define CLK_RPMH_ARC_EN_OFFSET 0
> > >> +#define CLK_RPMH_VRM_EN_OFFSET 4
> > >> +#define CLK_RPMH_VRM_OFF_VAL 0
> > >> +#define CLK_RPMH_VRM_ON_VAL 1
> > >> +#define CLK_RPMH_APPS_RSC_AO_STATE_MASK (BIT(RPMH_WAKE_ONLY_STATE)
| \
> > >> +                                        BIT(RPMH_ACTIVE_ONLY_STATE))
> > >> +#define CLK_RPMH_APPS_RSC_STATE_MASK (BIT(RPMH_WAKE_ONLY_STATE) | \
> > >> +                                     BIT(RPMH_ACTIVE_ONLY_STATE) | \
> > >> +                                     BIT(RPMH_SLEEP_STATE))
> > >> +struct clk_rpmh {
> > >> +       const char *res_name;
> > >> +       u32 res_addr;
> > >> +       u32 res_en_offset;
> > >> +       u32 res_on_val;
> > >> +       u32 res_off_val;
> > >> +       u32 state;
> > >> +       u32 aggr_state;
> > >> +       u32 last_sent_aggr_state;
> > >> +       u32 valid_state_mask;
> > >> +       struct rpmh_client *rpmh_client;
> > >> +       unsigned long rate;
> > >> +       struct clk_rpmh *peer;
> > >> +       struct clk_hw hw;
> > >
> > > I believe this member should go at the beginning of the structure. At
least
> > > that's what everyone else seems to do, and that's what the clk.txt
> > > documentation seems to ask for.
> > >
> >
> > Yes I missed that, would update it in the next patch series.

> Where is the documentation asking for that? There isn't any place that
> clk_hw should be in a structure. container_of() can figure it out all
> the time, and that macro is preferred instead of plain casts from one
> type to another because it provides slightly more type safety.

Perhaps I'm reading too strictly into the documentation, but this was the
passage that gave me that idea:

To construct a clk hardware structure for your platform you must define
the following::

struct clk_foo {
struct clk_hw hw;
... hardware specific data goes here ...
};

-Evan