Re: [PATCH v2] media: rkisp1: fix grey format iommu page faults

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On 23.01.22 16:32, Laurent Pinchart wrote:
Hi Dafna,

On Sun, Jan 23, 2022 at 11:50:26AM +0200, Dafna Hirschfeld wrote:
On 17.01.22 13:34, Kieran Bingham wrote:
Quoting Dafna Hirschfeld (2021-12-07 11:59:23)
Currently capturing grey format produces page faults
on both selfpath and mainpath. To support greyscale
we can capture YUV422 planar format and configure the U, V
buffers to the dummy buffer.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
---
This is v2 of the patch "media: rkisp1: remove support for V4L2_PIX_FMT_GREY"
In v1 I removed the grey format. In this version it is 'fixed'

   .../platform/rockchip/rkisp1/rkisp1-capture.c | 28 ++++++++++++++-----
   1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
index 768987d5f2dd..8e982dd0c740 100644
--- a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
+++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
@@ -249,7 +249,7 @@ static const struct rkisp1_capture_fmt_cfg rkisp1_sp_fmts[] = {
                  .fourcc = V4L2_PIX_FMT_GREY,
                  .uv_swap = 0,
                  .write_format = RKISP1_MI_CTRL_SP_WRITE_PLA,
-               .output_format = RKISP1_MI_CTRL_SP_OUTPUT_YUV400,
+               .output_format = RKISP1_MI_CTRL_SP_OUTPUT_YUV422,
                  .mbus = MEDIA_BUS_FMT_YUYV8_2X8,
          },
          /* rgb */
@@ -631,12 +631,26 @@ static void rkisp1_set_next_buf(struct rkisp1_capture *cap)
                  rkisp1_write(cap->rkisp1,
                               buff_addr[RKISP1_PLANE_Y],
                               cap->config->mi.y_base_ad_init);
-               rkisp1_write(cap->rkisp1,
-                            buff_addr[RKISP1_PLANE_CB],
-                            cap->config->mi.cb_base_ad_init);
-               rkisp1_write(cap->rkisp1,
-                            buff_addr[RKISP1_PLANE_CR],
-                            cap->config->mi.cr_base_ad_init);
+               /*
+                * In order to support grey format we capture
+                * YUV422 planar format from the camera and
+                * set the U and V planes to the dummy buffer
+                */
+               if (cap->pix.cfg->fourcc == V4L2_PIX_FMT_GREY) {
+                       rkisp1_write(cap->rkisp1,
+                                    cap->buf.dummy.dma_addr,
+                                    cap->config->mi.cb_base_ad_init);
+                       rkisp1_write(cap->rkisp1,
+                                    cap->buf.dummy.dma_addr,
+                                    cap->config->mi.cr_base_ad_init);
+               } else {
+                       rkisp1_write(cap->rkisp1,
+                                    buff_addr[RKISP1_PLANE_CB],
+                                    cap->config->mi.cb_base_ad_init);
+                       rkisp1_write(cap->rkisp1,
+                                    buff_addr[RKISP1_PLANE_CR],
+                                    cap->config->mi.cr_base_ad_init);
+               }
          } else {

Looking at this function, I think I would have initialised a local array
of addresses (either to zero, or to the dummy address?) to then set
values when appropriate, and reduce the number of calls to
rkisp1_write() to a single set of three after the processing.

It might make the function simpler, and more readable, but it's more
effort, and this does look like it will solve the greyscale format issue
as discussed in earlier threads so I'd leave it up to you if you want to
refactor.

Hi,
Yes, I'll do that.
Interestingly I found out that the patch causing the iommu page fault is

https://www.spinics.net/lists/linux-media/msg176089.html

Before that patch there are no iommu page faults but the video is corrupted.

I can't explain how I didn't find it before, I clearly remember testing the grey format.

It seems really weird indeed.

Are you getting IOMMU faults on both the main and self paths ?

Yes, both pathes. I get the page faults when checking out to this commit.
Maybe when I tested back then, the iommu was somehow disabled?


Reviewed-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>

                  /*
                   * Use the dummy space allocated by dma_alloc_coherent to




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