linux-kernel - Re: [PATCH 06/10] drm: bridge: it66121: Don't use DDC error IRQs

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Message-ID: <CAG3jFyvwQAXNsLBRj43ZcqX2kWkGT=iLr1NZshfXR6iRWkSdJA@mail.gmail.com>
Date:   Thu, 15 Dec 2022 12:18:46 +0100
From:   Robert Foss <robert.foss@...aro.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Phong LE <ple@...libre.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        list@...ndingux.net, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/10] drm: bridge: it66121: Don't use DDC error IRQs

On Wed, 14 Dec 2022 at 13:59, Paul Cercueil <paul@...pouillou.net> wrote:
>
> The DDC error IRQs will fire on the IT6610 every time the FIFO is empty,
> which is not very helpful. To resolve this, we can simply disable them,
> and handle DDC errors in it66121_wait_ddc_ready().
>
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>  drivers/gpu/drm/bridge/ite-it66121.c | 49 ++++++----------------------
>  1 file changed, 10 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
> index bfb9c87a7019..06fa59ae5ffc 100644
> --- a/drivers/gpu/drm/bridge/ite-it66121.c
> +++ b/drivers/gpu/drm/bridge/ite-it66121.c
> @@ -515,16 +515,6 @@ static int it66121_get_edid_block(void *context, u8 *buf,
>         offset = (block % 2) * len;
>         block = block / 2;
>
> -       ret = regmap_read(ctx->regmap, IT66121_INT_STATUS1_REG, &val);
> -       if (ret)
> -               return ret;
> -
> -       if (val & IT66121_INT_STATUS1_DDC_BUSHANG) {
> -               ret = it66121_abort_ddc_ops(ctx);
> -               if (ret)
> -                       return ret;
> -       }
> -
>         ret = it66121_clear_ddc_fifo(ctx);
>         if (ret)
>                 return ret;
> @@ -545,16 +535,6 @@ static int it66121_get_edid_block(void *context, u8 *buf,
>                 if (ret)
>                         return ret;
>
> -               ret = regmap_read(ctx->regmap, IT66121_INT_STATUS1_REG, &val);
> -               if (ret)
> -                       return ret;
> -
> -               if (val & IT66121_INT_STATUS1_DDC_BUSHANG) {
> -                       ret = it66121_abort_ddc_ops(ctx);
> -                       if (ret)
> -                               return ret;
> -               }
> -
>                 ret = it66121_preamble_ddc(ctx);
>                 if (ret)
>                         return ret;
> @@ -585,8 +565,10 @@ static int it66121_get_edid_block(void *context, u8 *buf,
>                 remain -= cnt;
>
>                 ret = it66121_wait_ddc_ready(ctx);
> -               if (ret)
> +               if (ret) {
> +                       it66121_abort_ddc_ops(ctx);
>                         return ret;
> +               }
>
>                 ret = regmap_noinc_read(ctx->regmap, IT66121_DDC_RD_FIFO_REG,
>                                         buf, cnt);
> @@ -671,11 +653,7 @@ static int it66121_bridge_attach(struct drm_bridge *bridge,
>         /* Per programming manual, sleep here for bridge to settle */
>         msleep(50);
>
> -       /* Start interrupts */
> -       return regmap_write_bits(ctx->regmap, IT66121_INT_MASK1_REG,
> -                                IT66121_INT_MASK1_DDC_NOACK |
> -                                IT66121_INT_MASK1_DDC_FIFOERR |
> -                                IT66121_INT_MASK1_DDC_BUSHANG, 0);
> +       return 0;
>  }
>
>  static int it66121_set_mute(struct it66121_ctx *ctx, bool mute)
> @@ -926,21 +904,14 @@ static irqreturn_t it66121_irq_threaded_handler(int irq, void *dev_id)
>         ret = regmap_read(ctx->regmap, IT66121_INT_STATUS1_REG, &val);
>         if (ret) {
>                 dev_err(dev, "Cannot read STATUS1_REG %d\n", ret);
> -       } else {
> -               if (val & IT66121_INT_STATUS1_DDC_FIFOERR)
> -                       it66121_clear_ddc_fifo(ctx);
> -               if (val & (IT66121_INT_STATUS1_DDC_BUSHANG |
> -                          IT66121_INT_STATUS1_DDC_NOACK))
> -                       it66121_abort_ddc_ops(ctx);
> -               if (val & IT66121_INT_STATUS1_HPD_STATUS) {
> -                       regmap_write_bits(ctx->regmap, IT66121_INT_CLR1_REG,
> -                                         IT66121_INT_CLR1_HPD, IT66121_INT_CLR1_HPD);
> +       } else if (val & IT66121_INT_STATUS1_HPD_STATUS) {
> +               regmap_write_bits(ctx->regmap, IT66121_INT_CLR1_REG,
> +                                 IT66121_INT_CLR1_HPD, IT66121_INT_CLR1_HPD);
>
> -                       status = it66121_is_hpd_detect(ctx) ? connector_status_connected
> -                                                           : connector_status_disconnected;
> +               status = it66121_is_hpd_detect(ctx) ? connector_status_connected
> +                       : connector_status_disconnected;
>
> -                       event = true;
> -               }
> +               event = true;
>         }
>
>         regmap_write_bits(ctx->regmap, IT66121_SYS_STATUS_REG,
> --
> 2.35.1
>

Reviewed-by: Robert Foss <robert.foss@...aro.org>