linux-kernel - Re: [V2] drm: msm: adreno: use IS_ERR() instead of null pointer check

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Message-ID: <b48957cb-f835-cfa4-34f7-0ab2f96474ed@linaro.org>
Date:   Sun, 3 Oct 2021 02:43:28 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Wang Qing <wangqing@...o.com>, Rob Clark <robdclark@...il.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        Sharat Masetty <smasetty@...eaurora.org>,
        Akhil P Oommen <akhilpo@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [V2] drm: msm: adreno: use IS_ERR() instead of null pointer check

On 07/11/2020 06:19, Wang Qing wrote:
> a6xx_gmu_get_mmio() never return null in case of error, but ERR_PTR(), so
> we should use IS_ERR() instead of null pointer check and IS_ERR_OR_NULL().

Not quite. a6xx_gmu_get_mmio() can return NULL, as it uses ioremap() 
internally. And ioremap returns NULL in case of error. So the proper 
check should be IS_ERR_OR_NULL().

> 
> Signed-off-by: Wang Qing <wangqing@...o.com>
> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index 491fee4..82420f7
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -492,7 +492,7 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   	void __iomem *seqptr = a6xx_gmu_get_mmio(pdev, "gmu_pdc_seq");
>   	uint32_t pdc_address_offset;
>   
> -	if (!pdcptr || !seqptr)
> +	if (IS_ERR(pdcptr) || IS_ERR(seqptr))
>   		goto err;
>   
>   	if (adreno_is_a618(adreno_gpu) || adreno_is_a640(adreno_gpu))
> @@ -580,9 +580,9 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   	wmb();
>   
>   err:
> -	if (!IS_ERR_OR_NULL(pdcptr))
> +	if (!IS_ERR(pdcptr))
>   		iounmap(pdcptr);
> -	if (!IS_ERR_OR_NULL(seqptr))
> +	if (!IS_ERR(seqptr))
>   		iounmap(seqptr);
>   }
>   
> 


-- 
With best wishes
Dmitry