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

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Message-ID: <e2d4e8b4-bab4-448f-8b67-21f2902fdcd2@linux.dev>
Date: Mon, 20 May 2024 19:11:10 +0800
From: Sui Jingfeng <sui.jingfeng@...ux.dev>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 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
Subject: Re: [PATCH] drm/bridge: adv7511: Exit interrupt handling when
 necessary

Hi,

On 5/20/24 06:11, Dmitry Baryshkov wrote:
> 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?
> 

I think this is may deserve another patch.

-- 
Best regards
Sui