Message-ID: <CAHCN7x+LasjE8NgkKzXZbxUZXLnhJhnuzfXPgbBKgtWeD0rEXA@mail.gmail.com>
Date: Mon, 17 Jun 2024 08:41:02 -0500
From: Adam Ford <aford173@...il.com>
To: Linux regressions mailing list <regressions@...ts.linux.dev>
Cc: dmitry.baryshkov@...aro.org, victor.liu@....com, sui.jingfeng@...ux.dev, 
	aford@...conembedded.com, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH V2] drm/bridge: adv7511: Fix Intermittent EDID failures

On Mon, Jun 17, 2024 at 8:29 AM Linux regression tracking (Thorsten
Leemhuis) <regressions@...mhuis.info> wrote:
>
> On 17.06.24 15:14, Adam Ford wrote:
> > On Mon, Jun 17, 2024 at 8:00 AM Linux regression tracking (Thorsten
> > Leemhuis) <regressions@...mhuis.info> wrote:
> >>
> >> [CCing the regression list, as it should be in the loop for regressions:
> >> https://docs.kernel.org/admin-guide/reporting-regressions.html]
> >>
> >> Hi! Top-posting for once, to make this easily accessible to everyone.
> >>
> >> Hmm, seem nobody took a look at below fix for a regression that seems to
> >> be caused by f3d9683346d6b1 ("drm/bridge: adv7511: Allow IRQ to share
> >> GPIO pins") [which went into v6.10-rc1].
> >>
> >> Adam and Dimitry, what are your stances on this patch from Adam? I'm
> >> asking, as you authored respectively committed the culprit?
> >
> > I learned of the regression from Liu Ying [...]
>
> Ohh, I'm very sorry, stupid me somehow missed that the Adam that was
> posting the fix was the same Adam that authored the culprit. :-( Seems I
> definitely need more coffee (or green tea in my case) or reduce the
> number or regressions on the stack. Please accept my apologies.
>
> Thx for the update anyway.

No problem.  Sent out a few e-mails and/or patches while tired and I
when I read them again when I was awake, I had to ask myself 'what
what was I thinking'

>
> > Dimitry had given me some suggestions, and from that,  I posted a V1.
> > Dmitry had some more followup suggestions [2] which resulted in the
> > V2.
> >> As far as I know, Liu was satisfied that this addressed the regression
> > he reported.
>
> So in that case the main question afaics is why this fix did not make
> any progress for more than two weeks now (at least afaics -- or did I
> miss something in that area, too?).

I have not seen anything either which is why I sent out the gentle
nudge last week.

adam
>
> Ciao, Thorsten
>
> >> On 01.06.24 15:24, Adam Ford wrote:
> >>> In the process of adding support for shared IRQ pins, a scenario
> >>> was accidentally created where adv7511_irq_process returned
> >>> prematurely causing the EDID to fail randomly.
> >>>
> >>> Since the interrupt handler is broken up into two main helper functions,
> >>> update both of them to treat the helper functions as IRQ handlers. These
> >>> IRQ routines process their respective tasks as before, but if they
> >>> determine that actual work was done, mark the respective IRQ status
> >>> accordingly, and delay the check until everything has been processed.
> >>>
> >>> This should guarantee the helper functions don't return prematurely
> >>> while still returning proper values of either IRQ_HANDLED or IRQ_NONE.
> >>>
> >>> Reported-by: Liu Ying <victor.liu@....com>
> >>> Fixes: f3d9683346d6 ("drm/bridge: adv7511: Allow IRQ to share GPIO pins")
> >>> Signed-off-by: Adam Ford <aford173@...il.com>
> >>> Tested-by: Liu Ying <victor.liu@....com> # i.MX8MP EVK ADV7535 EDID retrieval w/o IRQ
> >>> ---
> >>> V2:  Fix uninitialized cec_status
> >>>      Cut back a little on error handling to return either IRQ_NONE or
> >>>      IRQ_HANDLED.
> >>>
> >>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> >>> index ea271f62b214..ec0b7f3d889c 100644
> >>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
> >>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> >>> @@ -401,7 +401,7 @@ struct adv7511 {
> >>>
> >>>  #ifdef CONFIG_DRM_I2C_ADV7511_CEC
> >>>  int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511);
> >>> -void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1);
> >>> +int adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1);
> >>>  #else
> >>>  static inline int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> >>>  {
> >>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
> >>> index 44451a9658a3..651fb1dde780 100644
> >>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
> >>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
> >>> @@ -119,7 +119,7 @@ static void adv7511_cec_rx(struct adv7511 *adv7511, int rx_buf)
> >>>       cec_received_msg(adv7511->cec_adap, &msg);
> >>>  }
> >>>
> >>> -void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1)
> >>> +int adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1)
> >>>  {
> >>>       unsigned int offset = adv7511->info->reg_cec_offset;
> >>>       const u32 irq_tx_mask = ADV7511_INT1_CEC_TX_READY |
> >>> @@ -130,17 +130,21 @@ void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1)
> >>>                               ADV7511_INT1_CEC_RX_READY3;
> >>>       unsigned int rx_status;
> >>>       int rx_order[3] = { -1, -1, -1 };
> >>> -     int i;
> >>> +     int i, ret = 0;
> >>> +     int irq_status = IRQ_NONE;
> >>>
> >>> -     if (irq1 & irq_tx_mask)
> >>> +     if (irq1 & irq_tx_mask) {
> >>>               adv_cec_tx_raw_status(adv7511, irq1);
> >>> +             irq_status = IRQ_HANDLED;
> >>> +     }
> >>>
> >>>       if (!(irq1 & irq_rx_mask))
> >>> -             return;
> >>> +             return irq_status;
> >>>
> >>> -     if (regmap_read(adv7511->regmap_cec,
> >>> -                     ADV7511_REG_CEC_RX_STATUS + offset, &rx_status))
> >>> -             return;
> >>> +     ret = regmap_read(adv7511->regmap_cec,
> >>> +                     ADV7511_REG_CEC_RX_STATUS + offset, &rx_status);
> >>> +     if (ret < 0)
> >>> +             return irq_status;
> >>>
> >>>       /*
> >>>        * ADV7511_REG_CEC_RX_STATUS[5:0] contains the reception order of RX
> >>> @@ -172,6 +176,8 @@ void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1)
> >>>
> >>>               adv7511_cec_rx(adv7511, rx_buf);
> >>>       }
> >>> +
> >>> +     return IRQ_HANDLED;
> >>>  }
> >>>
> >>>  static int adv7511_cec_adap_enable(struct cec_adapter *adap, bool enable)
> >>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> >>> index 66ccb61e2a66..c8d2c4a157b2 100644
> >>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> >>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> >>> @@ -469,6 +469,8 @@ static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
> >>>  {
> >>>       unsigned int irq0, irq1;
> >>>       int ret;
> >>> +     int cec_status = IRQ_NONE;
> >>> +     int irq_status = IRQ_NONE;
> >>>
> >>>       ret = regmap_read(adv7511->regmap, ADV7511_REG_INT(0), &irq0);
> >>>       if (ret < 0)
> >>> @@ -478,29 +480,31 @@ static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
> >>>       if (ret < 0)
> >>>               return ret;
> >>>
> >>> -     /* If there is no IRQ to handle, exit indicating no IRQ data */
> >>> -     if (!(irq0 & (ADV7511_INT0_HPD | ADV7511_INT0_EDID_READY)) &&
> >>> -         !(irq1 & ADV7511_INT1_DDC_ERROR))
> >>> -             return -ENODATA;
> >>> -
> >>>       regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0);
> >>>       regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1);
> >>>
> >>> -     if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
> >>> +     if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder) {
> >>>               schedule_work(&adv7511->hpd_work);
> >>> +             irq_status = IRQ_HANDLED;
> >>> +     }
> >>>
> >>>       if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERROR) {
> >>>               adv7511->edid_read = true;
> >>>
> >>>               if (adv7511->i2c_main->irq)
> >>>                       wake_up_all(&adv7511->wq);
> >>> +             irq_status = IRQ_HANDLED;
> >>>       }
> >>>
> >>>  #ifdef CONFIG_DRM_I2C_ADV7511_CEC
> >>> -     adv7511_cec_irq_process(adv7511, irq1);
> >>> +     cec_status = adv7511_cec_irq_process(adv7511, irq1);
> >>>  #endif
> >>>
> >>> -     return 0;
> >>> +     /* If there is no IRQ to handle, exit indicating no IRQ data */
> >>> +     if (irq_status == IRQ_HANDLED || cec_status == IRQ_HANDLED)
> >>> +             return IRQ_HANDLED;
> >>> +
> >>> +     return IRQ_NONE;
> >>>  }
> >>>
> >>>  static irqreturn_t adv7511_irq_handler(int irq, void *devid)
> >>> @@ -509,7 +513,7 @@ static irqreturn_t adv7511_irq_handler(int irq, void *devid)
> >>>       int ret;
> >>>
> >>>       ret = adv7511_irq_process(adv7511, true);
> >>> -     return ret < 0 ? IRQ_NONE : IRQ_HANDLED;
> >>> +     return ret < 0 ? IRQ_NONE : ret;
> >>>  }
> >>>
> >>>  /* -----------------------------------------------------------------------------
> >
> >

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