[PATCH v5 09/12] media: microchip-isc: add SAMA7G5 hue and saturation controls
From: Balakrishnan Sambath
Date: Wed May 27 2026 - 07:09:56 EST
The CBHS (Contrast/Brightness/Hue/Saturation) block on SAMA7G5
operates in YCbCr space; expose hue and saturation as V4L2 controls
for the YUV/RGB output paths only. The SAMA5D2 has only the CBC
block (no hue/saturation), so the controls are gated on a new
has_cbhs flag.
Saturation uses the Q4 fixed-point range 0..127 with default 16
(1.0x) directly matching the CBHS_SAT register field. The control
state is initialised to neutral at probe so the first config_cbc()
write after streaming starts does not produce a grayscale image.
Co-developed-by: Balamanikandan Gunasundar <balamanikandan.gunasundar@xxxxxxxxxxxxx>
Signed-off-by: Balamanikandan Gunasundar <balamanikandan.gunasundar@xxxxxxxxxxxxx>
Signed-off-by: Balakrishnan Sambath <balakrishnan.s@xxxxxxxxxxxxx>
---
.../media/platform/microchip/microchip-isc-base.c | 75 ++++++++++++++++++++++
.../media/platform/microchip/microchip-isc-regs.h | 11 ++--
drivers/media/platform/microchip/microchip-isc.h | 3 +
.../platform/microchip/microchip-sama7g5-isc.c | 6 +-
4 files changed, 88 insertions(+), 7 deletions(-)
diff --git a/drivers/media/platform/microchip/microchip-isc-base.c b/drivers/media/platform/microchip/microchip-isc-base.c
index 04187127070d..cb338133d03f 100644
--- a/drivers/media/platform/microchip/microchip-isc-base.c
+++ b/drivers/media/platform/microchip/microchip-isc-base.c
@@ -859,6 +859,56 @@ static int isc_try_configure_pipeline(struct isc_device *isc)
return 0;
}
+static bool isc_format_has_chroma(u32 fourcc)
+{
+ switch (fourcc) {
+ case V4L2_PIX_FMT_YUV420:
+ case V4L2_PIX_FMT_YUV422P:
+ case V4L2_PIX_FMT_YUYV:
+ case V4L2_PIX_FMT_UYVY:
+ case V4L2_PIX_FMT_VYUY:
+ return true;
+ default:
+ return false;
+ }
+}
+
+/*
+ * isc_update_cbc_ctrl_activity() - Activate/deactivate CBC controls
+ *
+ * Called from isc_set_fmt(), isc_link_validate(), and isc_ctrl_init().
+ * At isc_ctrl_init() time isc->config.bits_pipeline is zero (no format
+ * has been negotiated yet), so all CBC controls are initially marked
+ * inactive. They become active once a format that includes CBHS in the
+ * pipeline is configured via VIDIOC_S_FMT or link validation.
+ */
+static void isc_update_cbc_ctrl_activity(struct isc_device *isc)
+{
+ struct v4l2_ctrl_handler *hdl = &isc->ctrls.handler;
+ struct v4l2_ctrl *brightness;
+ struct v4l2_ctrl *contrast;
+ struct v4l2_ctrl *hue;
+ struct v4l2_ctrl *saturation;
+ bool cbc_active = isc->config.bits_pipeline & CBHS_ENABLE;
+ bool chroma_active = cbc_active && isc_format_has_chroma(isc->config.fourcc);
+
+ brightness = v4l2_ctrl_find(hdl, V4L2_CID_BRIGHTNESS);
+ if (brightness)
+ v4l2_ctrl_activate(brightness, cbc_active);
+
+ contrast = v4l2_ctrl_find(hdl, V4L2_CID_CONTRAST);
+ if (contrast)
+ v4l2_ctrl_activate(contrast, cbc_active);
+
+ hue = v4l2_ctrl_find(hdl, V4L2_CID_HUE);
+ if (hue)
+ v4l2_ctrl_activate(hue, chroma_active);
+
+ saturation = v4l2_ctrl_find(hdl, V4L2_CID_SATURATION);
+ if (saturation)
+ v4l2_ctrl_activate(saturation, chroma_active);
+}
+
static int isc_try_fmt(struct isc_device *isc, struct v4l2_format *f)
{
struct v4l2_pix_format *pixfmt = &f->fmt.pix;
@@ -902,6 +952,7 @@ static int isc_set_fmt(struct isc_device *isc, struct v4l2_format *f)
/* make the try configuration active */
isc->config = isc->try_config;
isc->fmt = isc->try_fmt;
+ isc_update_cbc_ctrl_activity(isc);
dev_dbg(isc->dev, "ISC set_fmt to %.4s @%dx%d\n",
(char *)&f->fmt.pix.pixelformat,
@@ -989,6 +1040,7 @@ static int isc_link_validate(struct media_link *link)
return ret;
isc->config = isc->try_config;
+ isc_update_cbc_ctrl_activity(isc);
dev_dbg(isc->dev, "New ISC configuration in place\n");
@@ -1457,6 +1509,14 @@ static int isc_s_ctrl(struct v4l2_ctrl *ctrl)
case V4L2_CID_CONTRAST:
ctrls->contrast = ctrl->val & ISC_CBC_CONTRAST_MASK;
break;
+ case V4L2_CID_HUE:
+ if (isc->has_cbhs)
+ ctrls->hue = ctrl->val & ISC_CBHS_HUE_MASK;
+ break;
+ case V4L2_CID_SATURATION:
+ if (isc->has_cbhs)
+ ctrls->saturation = ctrl->val & ISC_CBHS_SAT_MASK;
+ break;
case V4L2_CID_GAMMA:
ctrls->gamma_index = ctrl->val;
break;
@@ -1464,6 +1524,7 @@ static int isc_s_ctrl(struct v4l2_ctrl *ctrl)
return -EINVAL;
}
+ /* config_cbc() flushes ctrls to hardware at stream start. */
return 0;
}
@@ -1647,6 +1708,19 @@ static int isc_ctrl_init(struct isc_device *isc)
ctrls->brightness = 0;
v4l2_ctrl_new_std(hdl, ops, V4L2_CID_BRIGHTNESS, -1024, 1023, 1, 0);
+ if (isc->has_cbhs) {
+ /*
+ * CBHS_HUE is a signed 9-bit value in degrees.
+ * CBHS_SAT is Q4 unsigned 7-bit, 16 = 1.0x.
+ * Initialize the kernel-side state to neutral here so the
+ * first config_cbc() call after streaming starts does not
+ * write zero (grayscale) to the hardware.
+ */
+ ctrls->hue = 0;
+ ctrls->saturation = 16;
+ v4l2_ctrl_new_std(hdl, ops, V4L2_CID_HUE, -180, 180, 1, 0);
+ v4l2_ctrl_new_std(hdl, ops, V4L2_CID_SATURATION, 0, 127, 1, 16);
+ }
v4l2_ctrl_new_std(hdl, ops, V4L2_CID_GAMMA, 0, isc->gamma_max, 1,
isc->gamma_default);
isc->awb_ctrl = v4l2_ctrl_new_std(hdl, &isc_awb_ops,
@@ -1665,6 +1739,7 @@ static int isc_ctrl_init(struct isc_device *isc)
}
v4l2_ctrl_activate(isc->do_wb_ctrl, false);
+ isc_update_cbc_ctrl_activity(isc);
isc->r_gain_ctrl = v4l2_ctrl_new_custom(hdl, &isc_r_gain_ctrl, NULL);
isc->b_gain_ctrl = v4l2_ctrl_new_custom(hdl, &isc_b_gain_ctrl, NULL);
diff --git a/drivers/media/platform/microchip/microchip-isc-regs.h b/drivers/media/platform/microchip/microchip-isc-regs.h
index e77e1d9a1db8..7f5c2e50e74b 100644
--- a/drivers/media/platform/microchip/microchip-isc-regs.h
+++ b/drivers/media/platform/microchip/microchip-isc-regs.h
@@ -268,10 +268,13 @@
#define ISC_CBC_CONTRAST 0x000003c0
#define ISC_CBC_CONTRAST_MASK GENMASK(11, 0)
-/* Hue Register */
-#define ISC_CBCHS_HUE 0x4e0
-/* Saturation Register */
-#define ISC_CBCHS_SAT 0x4e4
+/* Hue Register: signed 9-bit two's complement, covers -180 to +180 degrees */
+#define ISC_CBHS_HUE 0x4e0
+#define ISC_CBHS_HUE_MASK GENMASK(8, 0)
+
+/* Saturation Register: unsigned Q4 fixed-point (1.0 = 16, V4L2 range 0..127) */
+#define ISC_CBHS_SAT 0x4e4
+#define ISC_CBHS_SAT_MASK GENMASK(6, 0)
/* Offset for SUB422 register specific to sama5d2 product */
#define ISC_SAMA5D2_SUB422_OFFSET 0
diff --git a/drivers/media/platform/microchip/microchip-isc.h b/drivers/media/platform/microchip/microchip-isc.h
index 2282ef7dd596..36a9c0cb241f 100644
--- a/drivers/media/platform/microchip/microchip-isc.h
+++ b/drivers/media/platform/microchip/microchip-isc.h
@@ -139,6 +139,8 @@ struct isc_ctrls {
u32 brightness;
u32 contrast;
+ u32 hue;
+ u32 saturation;
u8 gamma_index;
#define ISC_WB_NONE 0
#define ISC_WB_AUTO 1
@@ -343,6 +345,7 @@ struct isc_device {
const u32 (*gamma_table)[GAMMA_ENTRIES];
u32 gamma_max;
u32 gamma_default;
+ bool has_cbhs;
u32 max_width;
u32 max_height;
diff --git a/drivers/media/platform/microchip/microchip-sama7g5-isc.c b/drivers/media/platform/microchip/microchip-sama7g5-isc.c
index 06aa801b88f9..f51c7cac25df 100644
--- a/drivers/media/platform/microchip/microchip-sama7g5-isc.c
+++ b/drivers/media/platform/microchip/microchip-sama7g5-isc.c
@@ -257,9 +257,8 @@ static void isc_sama7g5_config_cbc(struct isc_device *isc)
/* Configure what is set via v4l2 ctrls */
regmap_write(regmap, ISC_CBC_BRIGHT + isc->offsets.cbc, isc->ctrls.brightness);
regmap_write(regmap, ISC_CBC_CONTRAST + isc->offsets.cbc, isc->ctrls.contrast);
- /* Configure Hue and Saturation as neutral midpoint */
- regmap_write(regmap, ISC_CBCHS_HUE, 0);
- regmap_write(regmap, ISC_CBCHS_SAT, (1 << 4));
+ regmap_write(regmap, ISC_CBHS_HUE, isc->ctrls.hue);
+ regmap_write(regmap, ISC_CBHS_SAT, isc->ctrls.saturation);
}
static void isc_sama7g5_config_cc(struct isc_device *isc)
@@ -463,6 +462,7 @@ static int microchip_xisc_probe(struct platform_device *pdev)
isc->gamma_max = 2;
/* Index 1 in the SAMA7G5 table is gamma 1/2.2 (sRGB). */
isc->gamma_default = 1;
+ isc->has_cbhs = true;
if (of_machine_is_compatible("microchip,sam9x7")) {
isc->max_width = ISC_SAM9X7_MAX_SUPPORT_WIDTH;
--
2.34.1