media: imx-jpeg: Remove soft reset between frames encoding

Remove soft reset between frames, which was merely a workaround,
actually replace it with something less aggressive: clearing of jpeg stream
buffer pointer, via STM_CTRL[BITBUF_PTR_CLR].
According to the reference manual, the BITBUF_PTR_CLR is performed on
context switch, but, per hardware team recommendation, it is also working
without context switch, which is the case for this driver, for now.

Without soft reset and without BITBUF_PTR_CLR, successive encoding jobs
continue from where the previous left off, basically writing past the
v4l2 buffer.
Signed-off-by: Mirela Rabulea <mirela.rabulea@nxp.com>
Reviewed-by: Robert Chiras <robert.chiras@nxp.com>
Reviewed-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/imx-jpeg/mxc-jpeg.c

@@ -816,6 +816,7 @@ static void mxc_jpeg_config_dec_desc(struct vb2_buffer *out_buf,
 	img_fmt = mxc_jpeg_fourcc_to_imgfmt(q_data_cap->fmt->fourcc);
 	desc->stm_ctrl &= ~STM_CTRL_IMAGE_FORMAT(0xF); /* clear image format */
 	desc->stm_ctrl |= STM_CTRL_IMAGE_FORMAT(img_fmt);
+	desc->stm_ctrl |= STM_CTRL_BITBUF_PTR_CLR(1);
 	desc->line_pitch = q_data_cap->bytesperline[0];
 	mxc_jpeg_addrs(desc, dst_buf, src_buf, 0);
 	mxc_jpeg_set_bufsize(desc, ALIGN(vb2_plane_size(src_buf, 0), 1024));
@@ -842,6 +843,7 @@ static void mxc_jpeg_config_dec_desc(struct vb2_buffer *out_buf,
 	cfg_desc->imgsize |= MXC_JPEG_MIN_HEIGHT;
 	cfg_desc->line_pitch = MXC_JPEG_MIN_WIDTH * 2;
 	cfg_desc->stm_ctrl = STM_CTRL_IMAGE_FORMAT(MXC_JPEG_YUV422);
+	cfg_desc->stm_ctrl |= STM_CTRL_BITBUF_PTR_CLR(1);
 	cfg_desc->stm_bufbase = cfg_stream_handle;
 	cfg_desc->stm_bufsize = ALIGN(*cfg_size, 1024);
 	print_descriptor_info(jpeg->dev, cfg_desc);
@@ -885,6 +887,7 @@ static void mxc_jpeg_config_enc_desc(struct vb2_buffer *out_buf,
 	cfg_desc->stm_bufsize = 0x0;
 	cfg_desc->imgsize = 0;
 	cfg_desc->stm_ctrl = STM_CTRL_CONFIG_MOD(1);
+	cfg_desc->stm_ctrl |= STM_CTRL_BITBUF_PTR_CLR(1);
 
 	desc->next_descpt_ptr = 0; /* end of chain */
 
@@ -899,6 +902,7 @@ static void mxc_jpeg_config_enc_desc(struct vb2_buffer *out_buf,
 		dev_err(jpeg->dev, "No valid image format detected\n");
 	desc->stm_ctrl = STM_CTRL_CONFIG_MOD(0) |
 			 STM_CTRL_IMAGE_FORMAT(img_fmt);
+	desc->stm_ctrl |= STM_CTRL_BITBUF_PTR_CLR(1);
 	mxc_jpeg_addrs(desc, src_buf, dst_buf, 0);
 	dev_dbg(jpeg->dev, "cfg_desc:\n");
 	print_descriptor_info(jpeg->dev, cfg_desc);
@@ -954,11 +958,6 @@ static void mxc_jpeg_device_run(void *priv)
 		return;
 	}
 
-	/*
-	 * TODO: this reset should be removed, once we figure out
-	 * how to overcome hardware issues both on encoder and decoder
-	 */
-	mxc_jpeg_sw_reset(reg);
 	mxc_jpeg_enable(reg);
 	mxc_jpeg_set_l_endian(reg, 1);