linux-kernel - Re: [PATCH 2/4] media: rkisp1: Fix IRQ handler return values

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Message-ID: <CAHCN7xJqw-hSD7rWfxFq5NWnF+=RrpCWR+js9358jAL0_WzVFw@mail.gmail.com>
Date:   Tue, 5 Dec 2023 05:57:48 -0600
From:   Adam Ford <aford173@...il.com>
To:     Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc:     Dafna Hirschfeld <dafna@...tmail.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Paul Elder <paul.elder@...asonboard.com>,
        Alexander Stein <alexander.stein@...tq-group.com>,
        kieran.bingham@...asonboard.com, umang.jain@...asonboard.com,
        linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] media: rkisp1: Fix IRQ handler return values

On Tue, Dec 5, 2023 at 2:10 AM Tomi Valkeinen
<tomi.valkeinen@...asonboard.com> wrote:
>
> The IRQ handler rkisp1_isr() calls sub-handlers, all of which returns an
> irqreturn_t value, but rkisp1_isr() ignores those values and always
> returns IRQ_HANDLED.
>
> Fix this by collecting the return values, and returning IRQ_HANDLED or
> IRQ_NONE as appropriate.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> ---
>  drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> index 76f93614b4cf..1d60f4b8bd09 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> @@ -445,17 +445,27 @@ static int rkisp1_entities_register(struct rkisp1_device *rkisp1)
>
>  static irqreturn_t rkisp1_isr(int irq, void *ctx)
>  {
> +       irqreturn_t ret;
> +
>         /*
>          * Call rkisp1_capture_isr() first to handle the frame that
>          * potentially completed using the current frame_sequence number before
>          * it is potentially incremented by rkisp1_isp_isr() in the vertical
>          * sync.
>          */
> -       rkisp1_capture_isr(irq, ctx);
> -       rkisp1_isp_isr(irq, ctx);
> -       rkisp1_csi_isr(irq, ctx);
>
> -       return IRQ_HANDLED;
> +       ret = IRQ_NONE;
> +
> +       if (rkisp1_capture_isr(irq, ctx) == IRQ_HANDLED)
> +               ret = IRQ_HANDLED;
> +
> +       if (rkisp1_isp_isr(irq, ctx) == IRQ_HANDLED)
> +               ret = IRQ_HANDLED;
> +
> +       if (rkisp1_csi_isr(irq, ctx) == IRQ_HANDLED)
> +               ret = IRQ_HANDLED;
> +

It seems like we're throwing away the value of ret each time the
subsequent if statement is evaluated.  Whether or not they return
didn't matter before, and the only one that seems using the return
code is the last one.

Wouldn't it be simpler to use ret = rkisp1_capture_isr(irq, ctx), ret
= rkisp1_isp_isr(irq, ctx) and ret = rkisp1_csi_isr(irq, ctx) if we
care about the return code?

How do you expect this to return if one of the first two don't return
IRQ_HANDLED?

adam

> +       return ret;
>  }
>
>  static const char * const px30_isp_clks[] = {
>
> --
> 2.34.1
>