linux-kernel - Re: [PATCH] drm/bridge: it6505: Check power state with it6505->powered in IRQ handler

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Date:   Tue, 1 Aug 2023 11:37:38 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Pin-yen Lin <treapking@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: it6505: Check power state with
 it6505->powered in IRQ handler

On 27/07/2023 12:01, Pin-yen Lin wrote:
> On system resume, the driver might call it6505_poweron directly if the
> runtime PM hasn't been enabled. In such case, pm_runtime_get_if_in_use
> will always return 0 because dev->power.runtime_status stays at
> RPM_SUSPENDED, and the IRQ will never be handled.
> 
> Use it6505->powered from the driver struct fixes this because it always
> gets updated when it6505_poweron is called.
> 
> Fixes: 5eb9a4314053 ("drm/bridge: it6505: Guard bridge power in IRQ handler")
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> 
> ---
> 
>   drivers/gpu/drm/bridge/ite-it6505.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 6c2fcd8b8780..2f300f5ca051 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -2517,9 +2517,11 @@ static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
>   	};
>   	int int_status[3], i;
>   
> -	if (it6505->enable_drv_hold || pm_runtime_get_if_in_use(dev) <= 0)
> +	if (it6505->enable_drv_hold || !it6505->powered)
>   		return IRQ_HANDLED;
>   
> +	pm_runtime_get_sync(dev);
> +
>   	int_status[0] = it6505_read(it6505, INT_STATUS_01);
>   	int_status[1] = it6505_read(it6505, INT_STATUS_02);
>   	int_status[2] = it6505_read(it6505, INT_STATUS_03);

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>