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Message-ID: <6c693161-0e89-4f9d-9a92-18f3783eefd2@collabora.com>
Date:   Wed, 6 Dec 2023 11:19:32 +0100
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Subject: Re: [PATCH 3/4] media: mediatek: vcodec: Fix mtk_vcodec_mem_free()
 error log criteria
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To:     Fei Shao <fshao@chromium.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc:     Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Nicolas Dufresne <nicolas.dufresne@collabora.com>,
        =?UTF-8?B?TsOtY29sYXMgRi4gUi4gQS4gUHJhZG8=?= 
        <nfraprado@collabora.com>, Tiffany Lin <tiffany.lin@mediatek.com>,
        Yunfei Dong <yunfei.dong@mediatek.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, linux-mediatek@lists.infradead.org
References: <20231113123049.4117280-1-fshao@chromium.org>
 <20231113123049.4117280-4-fshao@chromium.org>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20231113123049.4117280-4-fshao@chromium.org>
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Il 13/11/23 13:26, Fei Shao ha scritto:
> mtk_vcodec_mem_free() shouldn't print error if the target DMA buffer has
> never been allocated or was freed properly in the previous call. That
> makes log confusing.
> 
> Update the error path to print log only when the caller attempts to free
> nonzero-size buffer with VA being NULL, which indicates something indeed
> went wrong.
> 
> This brings another benefit that the callers no more need to check
> mem->va explicitly to avoid the error, which can make the code more
> compact and neat.
> 
> Signed-off-by: Fei Shao <fshao@chromium.org>

I think that this error is supposed to catch two issues in one:
  - We're called to free no memory (something that does make no sense),
    this may happen for example when calling xxx_free() twice, and it
    is a mistake that *must* be fixed;
  - We're failing to free memory for real (which you covered)

....that said, I think that if you want to clarify the error messages
in this function, it should look something like this:

if (!mem->va) {
	mtk_v4l2_err(plat_dev, "%s: Tried to free a NULL VA", __func__);
	if (mem->size)
		mtk_v4l2_err(plat_dev, "Failed to free %lu bytes", mem->size);
	return;
}

Cheers,
Angelo