linux-kernel - Re: [PATCH] drm/bridge: adv7511: Exit interrupt handling when necessary

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Message-ID: <evnxopqt5be56vxuxqdj4l3mcd5nrrvucio7jhwgg4emraai3t@gherubdynyip>
Date: Mon, 20 May 2024 01:11:08 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Liu Ying <victor.liu@....com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, jonas@...boo.se, jernej.skrabec@...il.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, 
	daniel@...ll.ch, biju.das.jz@...renesas.com, u.kleine-koenig@...gutronix.de, 
	aford173@...il.com, jani.nikula@...el.com, bli@...g-olufsen.dk, 
	sui.jingfeng@...ux.dev
Subject: Re: [PATCH] drm/bridge: adv7511: Exit interrupt handling when
 necessary

On Thu, May 16, 2024 at 06:10:06PM +0800, Liu Ying wrote:
> Commit f3d9683346d6 ("drm/bridge: adv7511: Allow IRQ to share GPIO pins")
> fails to consider the case where adv7511->i2c_main->irq is zero, i.e.,
> no interrupt requested at all.
> 
> Without interrupt, adv7511_wait_for_edid() could return -EIO sometimes,
> because it polls adv7511->edid_read flag by calling adv7511_irq_process()
> a few times, but adv7511_irq_process() happens to refuse to handle
> interrupt by returning -ENODATA.  Hence, EDID retrieval fails randomly.
> 
> Fix the issue by checking adv7511->i2c_main->irq before exiting interrupt
> handling from adv7511_irq_process().
> 
> Fixes: f3d9683346d6 ("drm/bridge: adv7511: Allow IRQ to share GPIO pins")
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index 6089b0bb9321..2074fa3c1b7b 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -479,7 +479,8 @@ static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
>  		return ret;
>  
>  	/* If there is no IRQ to handle, exit indicating no IRQ data */
> -	if (!(irq0 & (ADV7511_INT0_HPD | ADV7511_INT0_EDID_READY)) &&
> +	if (adv7511->i2c_main->irq &&
> +	    !(irq0 & (ADV7511_INT0_HPD | ADV7511_INT0_EDID_READY)) &&
>  	    !(irq1 & ADV7511_INT1_DDC_ERROR))
>  		return -ENODATA;

I think it might be better to handle -ENODATA in adv7511_wait_for_edid()
instead. WDYT?

-- 
With best wishes
Dmitry