linux-kernel - Re: [PATCH 2/5] drm/exynos: mixer: Use platform_get

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Date:   Fri, 14 Jan 2022 20:20:05 +0900
From:   Inki Dae <inki.dae@...sung.com>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Joonyoung Shim <jy0922.shim@...sung.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org
Cc:     Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org,
        Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH 2/5] drm/exynos: mixer: Use platform_get_irq() to get
 the interrupt

Hi Lad Prabhakar,

21. 12. 23. 오전 4:01에 Lad Prabhakar 이(가) 쓴 글:
> platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
> allocation of IRQ resources in DT core code, this causes an issue
> when using hierarchical interrupt domains using "interrupts" property
> in the node as this bypassed the hierarchical setup and messed up the
> irq chaining.
> 
> In preparation for removal of static setup of IRQ resource from DT core
> code use platform_get_irq().
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> Hi,
> 
> Ideally I would expect the mixer_resources_init() to be called from probe
> instead from the bind callback. If platform_get_irq() returns -EPROBE_DEFER
> the bind callback will fail :(

If the bind callback failed then probe function of exynos drm driver will call -EPROBE_DEFER like below so it must be no problem :),
--------------------------------------------
in exynos_drm_platform_probe function
    component_master_add_with_match()

in component_master_add_with_match function
    try_to_bring_up_master()

Thanks,
Inki Dae

> 
> Cheers,
> Prabhakar
> ---
>  drivers/gpu/drm/exynos/exynos_mixer.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
> index 41c54f1f60bc..e5204be86093 100644
> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
> @@ -809,19 +809,17 @@ static int mixer_resources_init(struct mixer_context *mixer_ctx)
>  		return -ENXIO;
>  	}
>  
> -	res = platform_get_resource(mixer_ctx->pdev, IORESOURCE_IRQ, 0);
> -	if (res == NULL) {
> -		dev_err(dev, "get interrupt resource failed.\n");
> -		return -ENXIO;
> -	}
> +	ret = platform_get_irq(mixer_ctx->pdev, 0);
> +	if (ret < 0)
> +		return ret;
> +	mixer_ctx->irq = ret;
>  
> -	ret = devm_request_irq(dev, res->start, mixer_irq_handler,
> -						0, "drm_mixer", mixer_ctx);
> +	ret = devm_request_irq(dev, mixer_ctx->irq, mixer_irq_handler,
> +			       0, "drm_mixer", mixer_ctx);
>  	if (ret) {
>  		dev_err(dev, "request interrupt failed.\n");
>  		return ret;
>  	}
> -	mixer_ctx->irq = res->start;
>  
>  	return 0;
>  }
>