linux-kernel - [PATCH v4] media: mtk-vpu: Ensure alignment of 8 for DTCM buffer

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Date:   Mon, 20 Sep 2021 19:04:08 +0200
From:   Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
To:     linux-media@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Alexandre Courbot <acourbot@...omium.org>,
        dafna.hirschfeld@...labora.com, kernel@...labora.com,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        dafna3@...il.com, tiffany.lin@...iatek.com,
        andrew-ct.chen@...iatek.com, minghsiu.tsai@...iatek.com,
        houlong.wei@...iatek.com, mchehab@...nel.org,
        matthias.bgg@...il.com, hverkuil@...all.nl
Subject: [PATCH v4] media: mtk-vpu: Ensure alignment of 8 for DTCM buffer

From: Alexandre Courbot <acourbot@...omium.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@...omium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
Reviewed-by: Houlong Wei <houlong.wei@...iatek.com>
---
changes since v3:
1. multile -> multiple
2. add inline doc

changes since v2:
1. do the extra copy only if len is not multiple of 8

changes since v1:
1. change sign-off-by tags
2. change values to memset

 drivers/media/platform/mtk-vpu/mtk_vpu.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/mtk-vpu/mtk_vpu.c b/drivers/media/platform/mtk-vpu/mtk_vpu.c
index ec290dde59cf..1df031716c8f 100644
--- a/drivers/media/platform/mtk-vpu/mtk_vpu.c
+++ b/drivers/media/platform/mtk-vpu/mtk_vpu.c
@@ -349,7 +349,20 @@ int vpu_ipi_send(struct platform_device *pdev,
 		}
 	} while (vpu_cfg_readl(vpu, HOST_TO_VPU));
 
-	memcpy_toio(send_obj->share_buf, buf, len);
+	/*
+	 * when copying data to the vpu hardware, the memcpy_toio operation must copy
+	 * a multiple of 8. Otherwise the processing fails
+	 */
+	if (len % 8 != 0) {
+		unsigned char data[SHARE_BUF_SIZE];
+
+		memset(data + len, 0, sizeof(data) - len);
+		memcpy(data, buf, len);
+		memcpy_toio(send_obj->share_buf, data, round_up(len, 8));
+	} else {
+		memcpy_toio(send_obj->share_buf, buf, len);
+	}
+
 	writel(len, &send_obj->len);
 	writel(id, &send_obj->id);
 
-- 
2.17.1