Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <15a24b12-e296-9d4e-211f-55553ac8f7da@collabora.com>
Date:   Tue, 15 Feb 2022 10:41:21 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.5.1
Subject: Re: [PATCH v4] media: mtk-vpu: Ensure alignment of 8 for DTCM buffer
Content-Language: en-US
To:     linux-media@vger.kernel.org, linux-mediatek@lists.infradead.org,
        linux-kernel@vger.kernel.org
Cc:     Alexandre Courbot <acourbot@chromium.org>, kernel@collabora.com,
        dafna3@gmail.com, tiffany.lin@mediatek.com,
        andrew-ct.chen@mediatek.com, minghsiu.tsai@mediatek.com,
        houlong.wei@mediatek.com, mchehab@kernel.org,
        matthias.bgg@gmail.com, hverkuil@xs4all.nl
References: <20210920170408.1561-1-dafna.hirschfeld@collabora.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20210920170408.1561-1-dafna.hirschfeld@collabora.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Il 20/09/21 19:04, Dafna Hirschfeld ha scritto:
> From: Alexandre Courbot <acourbot@chromium.org>
> 
> When running memcpy_toio:
> memcpy_toio(send_obj->share_buf, buf, len);
> it was found that errors appear if len is not a multiple of 8:
> 
> [58.350841] mtk-mdp 14001000.rdma: processing failed: -22
> 
> This patch ensures the copy of a multiple of 8 size by calling
> round_up(len, 8) when copying
> 
> Fixes: e6599adfad30 ("media: mtk-vpu: avoid unaligned access to DTCM buffer.")
> Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
> Reviewed-by: Houlong Wei <houlong.wei@mediatek.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

I acknowledge that this patch is getting very old and stale, but after some
testing on MT8173, we were able to verify that it is essential for MediaTek MDP
functionality, along with some other patches.

Without this one, it won't work.

Keeping this in mind, I would propose to get this one picked before it gets
completely stale and requiring a rewrite.

Cheers,
Angelo