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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Wed, 12 May 2021 11:50:41 -0700
Message-ID: <CAE-0n517Xkj=-m=gYv-FkpWGP+xC=ht8pRTtr5V8CKdrNtq9gQ@mail.gmail.com>
Subject: Re: [PATCH v2] drm/msm/dp: handle irq_hpd with sink_count = 0 correctly
To:     Kuogee Hsieh <khsieh@codeaurora.org>, agross@kernel.org,
        bjorn.andersson@linaro.org, robdclark@gmail.com, sean@poorly.run,
        vkoul@kernel.org
Cc:     abhinavk@codeaurora.org, aravindh@codeaurora.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
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Quoting Kuogee Hsieh (2021-05-12 10:29:18)
> irq_hpd interrupt should be handled after dongle plugged in and
> before dongle unplugged. Hence irq_hpd interrupt is enabled at
> the end of the plugin handle and disabled at the beginning of
> unplugged handle. Current irq_hpd with sink_count = 0 is wrongly
> handled same as the dongle unplugged which tears down the mainlink
> and disables the phy. This patch fixes this problem by only tearing
> down the mainlink but keeping phy enabled at irq_hpd with
> sink_count = 0 handle so that next irq_hpe with sink_count =1 can be
> handled by setup mainlink only.
>
> Changes in v2:
> -- add ctrl->phy_Power_count
>
> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_catalog.c |  5 +--
>  drivers/gpu/drm/msm/dp/dp_ctrl.c    | 83 ++++++++++++++++++++++++++++++++++---
>  drivers/gpu/drm/msm/dp/dp_ctrl.h    |  2 +
>  drivers/gpu/drm/msm/dp/dp_display.c | 46 +++++++++++++++-----
>  4 files changed, 118 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c
> index b1a9b1b..f4f53f2 100644
> --- a/drivers/gpu/drm/msm/dp/dp_catalog.c
> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
> @@ -582,10 +582,9 @@ void dp_catalog_ctrl_hpd_config(struct dp_catalog *dp_catalog)
>
>         u32 reftimer = dp_read_aux(catalog, REG_DP_DP_HPD_REFTIMER);
>
> -       /* enable HPD interrupts */
> +       /* enable HPD plug and unplug interrupts */
>         dp_catalog_hpd_config_intr(dp_catalog,
> -               DP_DP_HPD_PLUG_INT_MASK | DP_DP_IRQ_HPD_INT_MASK
> -               | DP_DP_HPD_UNPLUG_INT_MASK | DP_DP_HPD_REPLUG_INT_MASK, true);
> +               DP_DP_HPD_PLUG_INT_MASK | DP_DP_HPD_UNPLUG_INT_MASK, true);
>
>         /* Configure REFTIMER and enable it */
>         reftimer |= DP_DP_HPD_REFTIMER_ENABLE;
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 8d59eb9..b5bed5f 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -77,6 +77,8 @@ struct dp_ctrl_private {
>         struct dp_parser *parser;
>         struct dp_catalog *catalog;
>
> +       int phy_power_count;

This is still redundant. Please restructure the code to call the power
on/off function in one place and the init/exit function in another so
that we don't have to reference count it.