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From:   Doug Anderson <dianders@chromium.org>
Date:   Mon, 13 Sep 2021 17:32:01 -0700
Message-ID: <CAD=FV=XDn3XWt5USOmkhikYMUqY1gt7MQfOQhu7v+soy=u3_0g@mail.gmail.com>
Subject: Re: [RFC PATCH v2 1/2] drm/bridge: parade-ps8640: Use regmap APIs
To:     Philip Chen <philipchen@chromium.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Stephen Boyd <swboyd@chromium.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Robert Foss <robert.foss@linaro.org>,
        dri-devel <dri-devel@lists.freedesktop.org>
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Precedence: bulk

Hi,

On Mon, Sep 13, 2021 at 2:33 PM Philip Chen <philipchen@chromium.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@chromium.org>