RE: [PATCH] media: s5p-mfc: Corrected NV12M/NV21M plane-sizes

-----Original Message-----
From: Aakarsh Jain <redacted>
Sent: 07 August 2024 17:23
To: 'Nicolas Dufresne' <redacted>; 'linux-arm-
kernel@lists.infradead.org' [off-list ref]; 'linux-
media@vger.kernel.org' [off-list ref]; 'linux-
kernel@vger.kernel.org' [off-list ref]
Cc: 'm.szyprowski@samsung.com' <m.szyprowski@samsung.com>;
'andrzej.hajda@intel.com' [off-list ref];
'mchehab@kernel.org' [off-list ref]; 'hverkuil-cisco@xs4all.nl'
[off-list ref]; 'krzysztof.kozlowski+dt@linaro.org'
[off-list ref]; 'linux-samsung-soc@vger.kernel.org'
[off-list ref]; 'gost.dev@samsung.com'
[off-list ref]; 'aswani.reddy@samsung.com'
[off-list ref]; 'pankaj.dubey@samsung.com'
[off-list ref]
Subject: RE: [PATCH] media: s5p-mfc: Corrected NV12M/NV21M plane-sizes

Hi Nocolas,

quoted

-----Original Message-----
From: Nicolas Dufresne <redacted>
Sent: 06 August 2024 20:08
To: Aakarsh Jain <redacted>; linux-arm-
kernel@lists.infradead.org; linux-media@vger.kernel.org; linux-
kernel@vger.kernel.org
Cc: m.szyprowski@samsung.com; andrzej.hajda@intel.com;
mchehab@kernel.org; hverkuil-cisco@xs4all.nl;
krzysztof.kozlowski+dt@linaro.org; linux-samsung-soc@vger.kernel.org;
gost.dev@samsung.com; aswani.reddy@samsung.com;
pankaj.dubey@samsung.com
Subject: Re: [PATCH] media: s5p-mfc: Corrected NV12M/NV21M plane-

sizes

quoted

Hi Jain,

I haven't dig much, but I have a quick question below.

Le mardi 06 août 2024 à 17:27 +0530, Aakarsh Jain a écrit :

quoted

There is a possibility of getting page fault if the overall buffer
size is not aligned to 256bytes. Since MFC does read operation only
and it won't corrupt the data values even if it reads the extra bytes.
Corrected luma and chroma plane sizes for V4L2_PIX_FMT_NV12M and
V4L2_PIX_FMT_NV21M pixel format.

Have you re-run v4l2 compliance ? (better be safe then sorry).

I ran v4l2-compliance and didn't found any issue wrt to the changes added in
this patch.
Please find the v4l2-compliance report attached.

quoted

quoted

Signed-off-by: Aakarsh Jain <redacted>
---
 .../media/platform/samsung/s5p-mfc/s5p_mfc_opr_v6.c    | 10 ++++++-

---

quoted

quoted

 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_opr_v6.c

b/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_opr_v6.c
index 73f7af674c01..03c957221fc4 100644

--- a/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_opr_v6.c
+++ b/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_opr_v6.c

@@ -498,8 +498,8 @@ static void s5p_mfc_dec_calc_dpb_size_v6(struct

s5p_mfc_ctx *ctx)

quoted

 	case V4L2_PIX_FMT_NV21M:
 		ctx->stride[0] = ALIGN(ctx->img_width,

S5P_FIMV_NV12MT_HALIGN_V6);

quoted

 		ctx->stride[1] = ALIGN(ctx->img_width,

S5P_FIMV_NV12MT_HALIGN_V6);

quoted

-		ctx->luma_size = calc_plane(ctx->stride[0], ctx->img_height);
-		ctx->chroma_size = calc_plane(ctx->stride[1], (ctx-
img_height / 2));
+		ctx->luma_size = calc_plane(ctx->img_width, ctx-
img_height);
+		ctx->chroma_size = calc_plane(ctx->img_width, (ctx-
img_height >>
+1));

These size needs to match the sizes reported through TRY_FMT (and
S_FMT) sizeimage for each planes. Is this code being call withing
try_fmt ? Will these value match or will this change cause the value to miss-

match ?

quoted

This code is getting called within try_fmt. In MFC driver we are not returning
any sizes in TRY_FMT. We are only validating codec and the pixel format. We
are setting luma, chroma and stride size in S_FMT to inform user space for
further buffer allocation. So, this change is not going to cause any mismatch.

quoted

The reason is that correct value is needed for allocating this memory
from the outside (like using a DMAbuf Heap). Perhaps its all right, let me

know.

quoted

Nicolas

quoted

 		break;
 	case V4L2_PIX_FMT_YUV420M:
 	case V4L2_PIX_FMT_YVU420M:

@@ -539,9 +539,11 @@ static void

s5p_mfc_dec_calc_dpb_size_v6(struct

quoted

quoted

s5p_mfc_ctx *ctx)  static void s5p_mfc_enc_calc_src_size_v6(struct
s5p_mfc_ctx *ctx)  {
 	unsigned int mb_width, mb_height;
+	unsigned int default_size;

 	mb_width = MB_WIDTH(ctx->img_width);
 	mb_height = MB_HEIGHT(ctx->img_height);
+	default_size = (mb_width * mb_height) * 256;

 	if (IS_MFCV12(ctx->dev)) {
 		switch (ctx->src_fmt->fourcc) {

@@ -549,8 +551,8 @@ static void s5p_mfc_enc_calc_src_size_v6(struct

s5p_mfc_ctx *ctx)

quoted

 		case V4L2_PIX_FMT_NV21M:
 			ctx->stride[0] = ALIGN(ctx->img_width,

S5P_FIMV_NV12M_HALIGN_V6);

quoted

 			ctx->stride[1] = ALIGN(ctx->img_width,

S5P_FIMV_NV12M_HALIGN_V6);

quoted

-			ctx->luma_size = ctx->stride[0] * ALIGN(ctx-
img_height, 16);
-			ctx->chroma_size =  ctx->stride[0] * ALIGN(ctx-
img_height / 2, 16);
+			ctx->luma_size = ALIGN(default_size, 256);
+			ctx->chroma_size = ALIGN(default_size / 2, 256);
 			break;
 		case V4L2_PIX_FMT_YUV420M:
 		case V4L2_PIX_FMT_YVU420M:

Gentle reminder to review this patch.