linux-kernel - Re: [PATCH] drm/bridge: ti-sn65dsi86: Clear old error bits before AUX transfers

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Message-ID: <CAF6AEGsYshudTEyL3vk+d3wZeYLOcMTqNR+sWZhBUZUzSZ9orA@mail.gmail.com>
Date:   Fri, 15 May 2020 14:48:33 -0700
From:   Rob Clark <robdclark@...il.com>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Rob Clark <robdclark@...omium.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Jonas Karlman <jonas@...boo.se>,
        David Airlie <airlied@...ux.ie>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Sandeep Panda <spanda@...eaurora.org>,
        Sean Paul <seanpaul@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bridge: ti-sn65dsi86: Clear old error bits before AUX transfers

On Fri, May 8, 2020 at 4:33 PM Douglas Anderson <dianders@...omium.org> wrote:
>
> The AUX channel transfer error bits in the status register are latched
> and need to be cleared.  Clear them before doing our transfer so we
> don't see old bits and get confused.
>
> Without this patch having a single failure would mean that all future
> transfers would look like they failed.
>
> Fixes: b814ec6d4535 ("drm/bridge: ti-sn65dsi86: Implement AUX channel")
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Reviewed-by: Rob Clark <robdclark@...il.com>

> ---
>
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 6ad688b320ae..d865cc2565bc 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -827,6 +827,12 @@ static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux,
>                                      buf[i]);
>         }
>
> +       /* Clear old status bits before start so we don't get confused */
> +       regmap_write(pdata->regmap, SN_AUX_CMD_STATUS_REG,
> +                    AUX_IRQ_STATUS_NAT_I2C_FAIL |
> +                    AUX_IRQ_STATUS_AUX_RPLY_TOUT |
> +                    AUX_IRQ_STATUS_AUX_SHORT);
> +
>         regmap_write(pdata->regmap, SN_AUX_CMD_REG, request_val | AUX_CMD_SEND);
>
>         ret = regmap_read_poll_timeout(pdata->regmap, SN_AUX_CMD_REG, val,
> --
> 2.26.2.645.ge9eca65c58-goog
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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