linux-kernel - Re: [PATCH v6 51/52] PM / devfreq: tegra30: Support interconnect and OPPs from device-tree

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Date:   Sun, 1 Nov 2020 23:44:40 +0900
From:   Chanwoo Choi <cwchoi00@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mikko Perttunen <cyndis@...si.fi>,
        Viresh Kumar <vireshk@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-tegra@...r.kernel.org,
        Linux PM list <linux-pm@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH v6 51/52] PM / devfreq: tegra30: Support interconnect and
 OPPs from device-tree

Hi Dmitry,

On Mon, Oct 26, 2020 at 7:22 AM Dmitry Osipenko <digetx@...il.com> wrote:
>
> This patch moves ACTMON driver away from generating OPP table by itself,
> transitioning it to use the table which comes from device-tree. This
> change breaks compatibility with older device-trees in order to bring
> support for the interconnect framework to the driver. This is a mandatory
> change which needs to be done in order to implement interconnect-based
> memory DVFS. Users of legacy device-trees will get a message telling that
> theirs DT needs to be upgraded. Now ACTMON issues memory bandwidth request
> using dev_pm_opp_set_bw(), instead of driving EMC clock rate directly.
>
> Tested-by: Peter Geis <pgwipeout@...il.com>
> Tested-by: Nicolas Chauvet <kwizart@...il.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 91 ++++++++++++++++---------------
>  1 file changed, 48 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 3f732ab53573..1b0b91a71886 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -19,6 +19,8 @@
>  #include <linux/reset.h>
>  #include <linux/workqueue.h>
>
> +#include <soc/tegra/fuse.h>
> +

This patch touches the OPP. Is it related to this change?

>  #include "governor.h"
>
>  #define ACTMON_GLB_STATUS                                      0x0
> @@ -155,6 +157,7 @@ struct tegra_devfreq_device {
>
>  struct tegra_devfreq {
>         struct devfreq          *devfreq;
> +       struct opp_table        *opp_table;
>
>         struct reset_control    *reset;
>         struct clk              *clock;
> @@ -612,34 +615,19 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>  static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>                                 u32 flags)
>  {
> -       struct tegra_devfreq *tegra = dev_get_drvdata(dev);
> -       struct devfreq *devfreq = tegra->devfreq;
>         struct dev_pm_opp *opp;
> -       unsigned long rate;
> -       int err;
> +       int ret;
>
>         opp = devfreq_recommended_opp(dev, freq, flags);
>         if (IS_ERR(opp)) {
> -               dev_err(dev, "Failed to find opp for %lu Hz\n", *freq);
> +               dev_err(dev, "failed to find opp for %lu Hz\n", *freq);

You used the 'Failed to' format in almost every error case.
Don't need to change it.
(snip)

Best Regards,
Chanwoo Choi