[PATCH v4 11/11] media: imx8-isi: Enable RAW10/12/14 output LSB alignment on i.MX952

[Guoniu Zhou]

Before i.MX952, the ISI RAW10/12/14 output formats are always
MSB-aligned, which is not compatible with the V4L2 RAW format
definition that requires LSB alignment.

>From i.MX952 onwards, the ISI introduces CHNL_CTRL_RAW_OUT_LSB_ALIGN
to select whether RAW10/12/14 outputs are MSB or LSB aligned. Enable
it so the driver produces correct V4L2-compatible LSB-aligned output.

Reviewed-by: Frank Li <Frank.Li at nxp.com>
Signed-off-by: Guoniu Zhou <guoniu.zhou at oss.nxp.com>
---
Changes in v4:
- Split RAW_IN_MSB_ALIGN into a separate preceding patch
- Split RAW format table and RAW14 changes into separate preceding patches
- Move isi_out_raw_shifted() to regs.h in the preceding workaround patch
- Rewrite commit message

Changes in v3:
- Use CHNL_IMG_CTRL_FORMAT_MASK instead of the removed per-platform format_mask (Laurent)
- Derive raw_out_lsb from the model field instead of dedicated platform data (Laurent)
- Clarify the CHNL_IMG_CTRL_FORMAT_RAW14 comment: the format is
  documented on i.MX{8ULP,91,93,95,952} but only used on i.MX952
- Update the mxc_isi_channel_set_output_format() comment wording
- Rewrite commit message
- Add Reviewed-by tag from Frank
---
 drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c  | 37 +++++++++++++++++++---
 .../media/platform/nxp/imx8-isi/imx8-isi-regs.h    |  5 +--
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
index b3f32b9796d5..6733776e72aa 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
@@ -311,12 +311,24 @@ static void mxc_isi_channel_set_panic_threshold(struct mxc_isi_pipe *pipe)
  * RAW samples from either the high or low bits, as both LSB and MSB
  * alignment can be selected in the gasket.
  *
- * On i.MX95, the CSI formatter provides MSB-aligned RAW data, so the ISI
- * must select RAW samples from the high bits of the Pixel Link bus.
+ * Starting with i.MX95, the CSI formatter provides MSB-aligned RAW data,
+ * so the ISI must select RAW samples from the high bits of the Pixel Link
+ * bus.
  */
 static bool isi_raw_in_msb(const struct mxc_isi_plat_data *pdata)
 {
-	return pdata->model == MXC_ISI_IMX95;
+	return pdata->model == MXC_ISI_IMX95 ||
+	       pdata->model == MXC_ISI_IMX952;
+}
+
+/*
+ * Starting with i.MX952, the ISI can output RAW10/12/14 formats with LSB
+ * alignment, matching the V4L2 requirement. Older platforms lack this
+ * capability and need the RAW16 workaround.
+ */
+static bool isi_raw_out_lsb(const struct mxc_isi_plat_data *pdata)
+{
+	return pdata->model == MXC_ISI_IMX952;
 }
 
 static void mxc_isi_channel_set_control(struct mxc_isi_pipe *pipe,
@@ -377,6 +389,13 @@ static void mxc_isi_channel_set_control(struct mxc_isi_pipe *pipe,
 	if (isi_raw_in_msb(pipe->isi->pdata))
 		val |= CHNL_CTRL_RAW_IN_MSB_ALIGN;
 
+	/*
+	 * Enable RAW10/12/14 output LSB alignment to match the
+	 * V4L2 requirement that RAW formats are LSB-aligned.
+	 */
+	if (isi_raw_out_lsb(pipe->isi->pdata))
+		val |= CHNL_CTRL_RAW_OUT_LSB_ALIGN;
+
 	mxc_isi_write(pipe, CHNL_CTRL, val);
 
 	mutex_unlock(&pipe->lock);
@@ -430,13 +449,23 @@ void mxc_isi_channel_set_output_format(struct mxc_isi_pipe *pipe,
 				       const struct mxc_isi_format_info *info,
 				       struct v4l2_pix_format_mplane *format)
 {
+	const struct mxc_isi_plat_data *pdata = pipe->isi->pdata;
 	u32 val;
 	u32 fmt;
 
 	/* set outbuf format */
 	dev_dbg(pipe->isi->dev, "output format %p4cc", &format->pixelformat);
 
-	fmt = isi_out_raw_shifted(info->isi_out_format)
+	/*
+	 * Before i.MX952, the ISI shifts the 10/12/14-bit formats left
+	 * by 6, 4 and 2 bits when using CHNL_IMG_CTRL_FORMAT_RAW10/12/14
+	 * respectively, to align the bits to the left and pad with zeros in
+	 * the LSBs. The corresponding V4L2 formats are however right-aligned,
+	 * we have to use CHNL_IMG_CTRL_FORMAT_RAW16 to avoid the left shift.
+	 * Starting with i.MX952, the ISI supports RAW10/12/14 LSB output
+	 * alignment, so skip the above workaround.
+	 */
+	fmt = !isi_raw_out_lsb(pdata) && isi_out_raw_shifted(info->isi_out_format)
 	    ? CHNL_IMG_CTRL_FORMAT_RAW16
 	    : info->isi_out_format;
 
diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h b/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h
index d2b8a26b7c21..075fc6848213 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h
@@ -20,7 +20,8 @@
 #define CHNL_CTRL_CHAIN_BUF_NO_CHAIN				0
 #define CHNL_CTRL_CHAIN_BUF_2_CHAIN				1
 #define CHNL_CTRL_SW_RST					BIT(24)
-#define CHNL_CTRL_RAW_IN_MSB_ALIGN				BIT(22)	/* i.MX{91,93,95} */
+#define CHNL_CTRL_RAW_OUT_LSB_ALIGN				BIT(23)	/* i.MX952 only */
+#define CHNL_CTRL_RAW_IN_MSB_ALIGN				BIT(22)	/* i.MX{91,93,95,952} */
 /*
  * CHNL_CTRL_BLANK_PXL: i.MX8{QM,QXP} only
  * CHNL_CTRL_VC_ID_1, CHNL_CTRL_VC_ID_1_MASK: i.MX{95,952} only
@@ -90,7 +91,7 @@
 #define CHNL_IMG_CTRL_FORMAT_YUV420_3P10P			0x3a
 #define CHNL_IMG_CTRL_FORMAT_YUV420_2P12			0x3d
 #define CHNL_IMG_CTRL_FORMAT_YUV420_3P12			0x3e
-#define CHNL_IMG_CTRL_FORMAT_RAW14				0x41	/* i.MX{8ULP,91,93,95} */
+#define CHNL_IMG_CTRL_FORMAT_RAW14				0x41	/* i.MX{8ULP,91,93,95,952}, used on i.MX952 only */
 
 #define CHNL_IMG_CTRL_GBL_ALPHA_VAL(n)				((n) << 16)
 #define CHNL_IMG_CTRL_GBL_ALPHA_VAL_MASK			GENMASK(23, 16)

-- 
2.34.1