linux-kernel - Re: [RFC PATCH v2 1/2] drm/bridge: parade-ps8640: Use regmap APIs

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Date:   Tue, 14 Sep 2021 16:31:24 -0700
From:   Philip Chen <philipchen@...omium.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC PATCH v2 1/2] drm/bridge: parade-ps8640: Use regmap APIs

Hi, Doug

Thanks for the review.
I fixed the nits you pointed out in v3.
PTAL.

On Mon, Sep 13, 2021 at 5:32 PM Doug Anderson <dianders@...omium.org> wrote:
>
> Hi,
>
> On Mon, Sep 13, 2021 at 2:33 PM Philip Chen <philipchen@...omium.org> wrote:
> >
> > diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> > index 685e9c38b2db..1b2414601538 100644
> > --- a/drivers/gpu/drm/bridge/parade-ps8640.c
> > +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> > @@ -9,6 +9,7 @@
> >  #include <linux/i2c.h>
> >  #include <linux/module.h>
> >  #include <linux/of_graph.h>
> > +#include <linux/regmap.h>
> >  #include <linux/regulator/consumer.h>
> >
> >  #include <drm/drm_bridge.h>
> > @@ -31,6 +32,11 @@
> >
> >  #define NUM_MIPI_LANES         4
> >
> > +#define COMMON_PS8640_REGMAP_CONFIG \
> > +       .reg_bits = 8, \
> > +       .val_bits = 8, \
> > +       .cache_type = REGCACHE_NONE
>
> At some point we should see if we get any speed gains by actually
> caching, but that could be done later and isn't terribly high
> priority.
>
>
> > +
> >  /*
> >   * PS8640 uses multiple addresses:
> >   * page[0]: for DP control
> > @@ -64,12 +70,48 @@ struct ps8640 {
> >         struct drm_bridge *panel_bridge;
> >         struct mipi_dsi_device *dsi;
> >         struct i2c_client *page[MAX_DEVS];
> > +       struct regmap   *regmap[MAX_DEVS];
> >         struct regulator_bulk_data supplies[2];
> >         struct gpio_desc *gpio_reset;
> >         struct gpio_desc *gpio_powerdown;
> >         bool powered;
> >  };
> >
> > +static const struct regmap_config ps8640_regmap_config[] = {
> > +       [PAGE0_DP_CNTL] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xbf
> > +       },
> > +       [PAGE1_VDO_BDG] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xff
> > +       },
> > +       [PAGE2_TOP_CNTL] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xff
> > +       },
> > +       [PAGE3_DSI_CNTL1] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xff
> > +       },
> > +       [PAGE4_MIPI_PHY] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xff
> > +       },
> > +       [PAGE5_VPLL] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0x7f
> > +       },
> > +       [PAGE6_DSI_CNTL2] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xff
> > +       },
> > +       [PAGE7_SPI_CNTL] = {
> > +               COMMON_PS8640_REGMAP_CONFIG,
> > +               .max_register = 0xff
> > +       }
>
> nit: stylistically it's nice to add a "," after the last brace too.
> It's not technically needed but it makes diffs cleaner if another
> config is later added.
>
>
> > @@ -362,6 +390,10 @@ static int ps8640_probe(struct i2c_client *client)
> >
> >         ps_bridge->page[PAGE0_DP_CNTL] = client;
> >
> > +       ps_bridge->regmap[PAGE0_DP_CNTL] = devm_regmap_init_i2c(client, ps8640_regmap_config);
> > +       if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]))
> > +               return PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]);
>
> I'm a huge fan of dev_err_probe(). I wonder if it makes sense to use
> it here? Untested:
>
> if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]))
>   return dev_err_probe(dev, PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]),
>                        "Error initting page 0 regmap\n");
>
>
> All of that is just nits, so:
>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>