media: imx: imx7-media-csi: Use dual sampling for YUV 1X16

[platform/kernel/linux-rpi.git] / drivers / staging / media / imx / imx7-media-csi.c

diff --git a/drivers/staging/media/imx/imx7-media-csi.c b/drivers/staging/media/imx/imx7-media-csi.c
index 32311fc..8467a14 100644 (file)
--- a/drivers/staging/media/imx/imx7-media-csi.c
+++ b/drivers/staging/media/imx/imx7-media-csi.c
@@ -498,16 +498,40 @@ static void imx7_csi_configure(struct imx7_csi *csi)
                        cr3 |= BIT_TWO_8BIT_SENSOR;
                        cr18 |= BIT_MIPI_DATA_FORMAT_RAW14;
                        break;
+
                /*
-                * CSI-2 sources are supposed to use the 1X16 formats, but not
-                * all of them comply. Support both variants.
+                * The CSI bridge has a 16-bit input bus. Depending on the
+                * connected source, data may be transmitted with 8 or 10 bits
+                * per clock sample (in bits [9:2] or [9:0] respectively) or
+                * with 16 bits per clock sample (in bits [15:0]). The data is
+                * then packed into a 32-bit FIFO (as shown in figure 13-11 of
+                * the i.MX8MM reference manual rev. 3).
+                *
+                * The data packing in a 32-bit FIFO input word is controlled by
+                * the CR3 TWO_8BIT_SENSOR field (also known as SENSOR_16BITS in
+                * the i.MX8MM reference manual). When set to 0, data packing
+                * groups four 8-bit input samples (bits [9:2]). When set to 1,
+                * data packing groups two 16-bit input samples (bits [15:0]).
+                *
+                * The register field CR18 MIPI_DOUBLE_CMPNT also needs to be
+                * configured according to the input format for YUV 4:2:2 data.
+                * The field controls the gasket between the CSI-2 receiver and
+                * the CSI bridge. On i.MX7 and i.MX8MM, the field must be set
+                * to 1 when the CSIS outputs 16-bit samples. On i.MX8MQ, the
+                * gasket ignores the MIPI_DOUBLE_CMPNT bit and YUV 4:2:2 always
+                * uses 16-bit samples. Setting MIPI_DOUBLE_CMPNT in that case
+                * has no effect, but doesn't cause any issue.
                 */
                case MEDIA_BUS_FMT_UYVY8_2X8:
-               case MEDIA_BUS_FMT_UYVY8_1X16:
                case MEDIA_BUS_FMT_YUYV8_2X8:
-               case MEDIA_BUS_FMT_YUYV8_1X16:
                        cr18 |= BIT_MIPI_DATA_FORMAT_YUV422_8B;
                        break;
+               case MEDIA_BUS_FMT_UYVY8_1X16:
+               case MEDIA_BUS_FMT_YUYV8_1X16:
+                       cr3 |= BIT_TWO_8BIT_SENSOR;
+                       cr18 |= BIT_MIPI_DATA_FORMAT_YUV422_8B |
+                               BIT_MIPI_DOUBLE_CMPNT;
+                       break;
                }
        }