linux-kernel - Re: [PATCH 2/2] drm/msm/dp: unplug interrupt missed after irq

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Date:   Wed, 13 Jan 2021 15:46:23 -0800
From:   khsieh@...eaurora.org
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, tanmay@...eaurora.org, abhinavk@...eaurora.org,
        aravindh@...eaurora.org, airlied@...ux.ie, daniel@...ll.ch,
        linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/msm/dp: unplug interrupt missed after irq_hpd
 handler

On 2021-01-13 12:23, Stephen Boyd wrote:
> Quoting khsieh@...eaurora.org (2021-01-13 09:48:25)
>> On 2021-01-11 11:54, Stephen Boyd wrote:
>> > Quoting Kuogee Hsieh (2021-01-07 12:30:25)
>> >> There is HPD unplug interrupts missed at scenario of an irq_hpd
>> >> followed by unplug interrupts with around 10 ms in between.
>> >> Since both AUX_SW_RESET and DP_SW_RESET clear pending HPD interrupts,
>> >> irq_hpd handler should not issues either aux or sw reset to avoid
>> >> following unplug interrupt be cleared accidentally.
>> >
>> > So the problem is that we're resetting the DP aux phy in the middle of
>> > the HPD state machine transitioning states?
>> >
>> yes, after reset aux, hw clear pending hpd interrupts
>> >>
>> >> Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
>> >> ---
>> >> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c
>> >> b/drivers/gpu/drm/msm/dp/dp_catalog.c
>> >> index 44f0c57..9c0ce98 100644
>> >> --- a/drivers/gpu/drm/msm/dp/dp_catalog.c
>> >> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
>> >> @@ -190,6 +190,18 @@ int dp_catalog_aux_clear_hw_interrupts(struct
>> >> dp_catalog *dp_catalog)
>> >>         return 0;
>> >>  }
>> >>
>> >> +/**
>> >> + * dp_catalog_aux_reset() - reset AUX controller
>> >> + *
>> >> + * @aux: DP catalog structure
>> >> + *
>> >> + * return: void
>> >> + *
>> >> + * This function reset AUX controller
>> >> + *
>> >> + * NOTE: reset AUX controller will also clear any pending HPD related
>> >> interrupts
>> >> + *
>> >> + */
>> >>  void dp_catalog_aux_reset(struct dp_catalog *dp_catalog)
>> >>  {
>> >>         u32 aux_ctrl;
>> >> @@ -483,6 +495,18 @@ int dp_catalog_ctrl_set_pattern(struct dp_catalog
>> >> *dp_catalog,
>> >>         return 0;
>> >>  }
>> >>
>> >> +/**
>> >> + * dp_catalog_ctrl_reset() - reset DP controller
>> >> + *
>> >> + * @aux: DP catalog structure
>> >
>> > It's called dp_catalog though.
>> registers access are through dp_catalog_xxxx
> 
> Agreed. The variable is not called 'aux' though, it's called
> 'dp_catalog'.
> 
>> >
>> >> + *
>> >> + * return: void
>> >> + *
>> >> + * This function reset DP controller
>> >
>> > resets the
>> >
>> >> + *
>> >> + * NOTE: reset DP controller will also clear any pending HPD related
>> >> interrupts
>> >> + *
>> >> + */
>> >>  void dp_catalog_ctrl_reset(struct dp_catalog *dp_catalog)
> 
> Right here.

fixed at v2
> 
>> >>  {
>> >>         u32 sw_reset;
>> >> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> >> b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> >> index e3462f5..f96c415 100644
>> >> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> >> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> >> @@ -1296,7 +1296,8 @@ static int dp_ctrl_setup_main_link(struct
>> >> dp_ctrl_private *ctrl,
>> >>          * transitioned to PUSH_IDLE. In order to start transmitting
>> >>          * a link training pattern, we have to first do soft reset.
>> >>          */
>> >> -       dp_catalog_ctrl_reset(ctrl->catalog);
>> >> +       if (*training_step != DP_TRAINING_NONE)
>> >
>> > Can we check for the positive value instead? i.e.
>> > DP_TRAINING_1/DP_TRAINING_2
>> >
> 
> Any answer?

fixed at v2