On 17/01/2026 15:36, David Heidelberg via B4 Relay wrote:
From: David Heidelberg <[email protected]>
Ensure that the link frequency divider correctly accounts for C-PHY
operation. The divider differs between D-PHY and C-PHY, as described
in the MIPI CSI-2 specification.
For more details, see:
https://docs.kernel.org/driver-api/media/tx-rx.html#pixel-rate
Suggested-by: Sakari Ailus <[email protected]>
Signed-off-by: David Heidelberg <[email protected]>
---
drivers/media/platform/qcom/camss/camss-csid.c | 2 +-
drivers/media/platform/qcom/camss/camss-csiphy.c | 6 ++++--
drivers/media/platform/qcom/camss/camss.c | 16 +++++++++++++---
drivers/media/platform/qcom/camss/camss.h | 2 +-
4 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/media/platform/qcom/camss/camss-csid.c
b/drivers/media/platform/qcom/camss/camss-csid.c
index b50b0cfe280c1..24f244d2959c9 100644
--- a/drivers/media/platform/qcom/camss/camss-csid.c
+++ b/drivers/media/platform/qcom/camss/camss-csid.c
@@ -545,7 +545,7 @@ static int csid_set_clock_rates(struct csid_device *csid)
fmt = csid_get_fmt_entry(csid->res->formats->formats,
csid->res->formats->nformats,
csid->fmt[MSM_CSIPHY_PAD_SINK].code);
link_freq = camss_get_link_freq(&csid->subdev.entity, fmt->bpp,
- csid->phy.lane_cnt);
+ csid->phy.lane_cnt, csid->phy.cphy);
Just pass &csid->phy ..
if (link_freq < 0)
link_freq = 0;
diff --git a/drivers/media/platform/qcom/camss/camss-csiphy.c b/drivers/media/platform/qcom/camss/camss-csiphy.c
index 08dd238e52799..1ea0d0ef354ff 100644
--- a/drivers/media/platform/qcom/camss/camss-csiphy.c
+++ b/drivers/media/platform/qcom/camss/camss-csiphy.c
@@ -144,8 +144,9 @@ static int csiphy_set_clock_rates(struct csiphy_device
*csiphy)
u8 bpp = csiphy_get_bpp(csiphy->res->formats->formats,
csiphy->res->formats->nformats,
csiphy->fmt[MSM_CSIPHY_PAD_SINK].code);
u8 num_lanes = csiphy->cfg.csi2->lane_cfg.num_data;
+ bool cphy = csiphy->cfg.csi2->lane_cfg.phy_cfg == V4L2_MBUS_CSI2_CPHY;
- link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, num_lanes);
+ link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, num_lanes,
cphy);
CPHY shouldn't be a boolean special case - you have a use-case for the
containing structure, so pass that instead.
if (link_freq < 0)
link_freq = 0;
@@ -270,9 +271,10 @@ static int csiphy_stream_on(struct csiphy_device *csiphy)
u8 bpp = csiphy_get_bpp(csiphy->res->formats->formats,
csiphy->res->formats->nformats,
csiphy->fmt[MSM_CSIPHY_PAD_SINK].code);
u8 num_lanes = csiphy->cfg.csi2->lane_cfg.num_data;
+ bool cphy = csiphy->cfg.csi2->lane_cfg.phy_cfg == V4L2_MBUS_CSI2_CPHY;
u8 val;
- link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, num_lanes);
+ link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, num_lanes,
cphy);
if (link_freq < 0) {
dev_err(csiphy->camss->dev,
diff --git a/drivers/media/platform/qcom/camss/camss.c
b/drivers/media/platform/qcom/camss/camss.c
index ea0c8cf3cd806..556fedd92e065 100644
--- a/drivers/media/platform/qcom/camss/camss.c
+++ b/drivers/media/platform/qcom/camss/camss.c
@@ -32,6 +32,14 @@
#define CAMSS_CLOCK_MARGIN_NUMERATOR 105
#define CAMSS_CLOCK_MARGIN_DENOMINATOR 100
+/*
+ * C-PHY encodes data by 16/7 ~ 2.28 bits/symbol
+ * D-PHY doesn't encode data, thus 16/16 = 1 b/s
+ */
+#define CAMSS_COMMON_PHY_DIVIDENT 16
+#define CAMSS_CPHY_DIVISOR 7
+#define CAMSS_DPHY_DIVISOR 16
+
static const struct parent_dev_ops vfe_parent_dev_ops;
static const struct camss_subdev_resources csiphy_res_8x16[] = {
@@ -4280,20 +4288,22 @@ struct media_pad *camss_find_sensor_pad(struct
media_entity *entity)
* camss_get_link_freq - Get link frequency from sensor
* @entity: Media entity in the current pipeline
* @bpp: Number of bits per pixel for the current format
- * @lanes: Number of lanes in the link to the sensor
+ * @nr_of_lanes: Number of lanes in the link to the sensor
*
* Return link frequency on success or a negative error code otherwise
*/
s64 camss_get_link_freq(struct media_entity *entity, unsigned int bpp,
- unsigned int lanes)
+ unsigned int nr_of_lanes, bool cphy)
{
struct media_pad *sensor_pad;
+ unsigned int div = nr_of_lanes * 2 * (cphy ? CAMSS_CPHY_DIVISOR :
+ CAMSS_DPHY_DIVISOR);
sensor_pad = camss_find_sensor_pad(entity);
if (!sensor_pad)
return -ENODEV;
- return v4l2_get_link_freq(sensor_pad, bpp, 2 * lanes);
+ return v4l2_get_link_freq(sensor_pad, CAMSS_COMMON_PHY_DIVIDENT * bpp,
div);
}
/*
diff --git a/drivers/media/platform/qcom/camss/camss.h
b/drivers/media/platform/qcom/camss/camss.h
index 6d048414c919e..6bf7738837b89 100644
--- a/drivers/media/platform/qcom/camss/camss.h
+++ b/drivers/media/platform/qcom/camss/camss.h
@@ -163,7 +163,7 @@ int camss_enable_clocks(int nclocks, struct camss_clock
*clock,
void camss_disable_clocks(int nclocks, struct camss_clock *clock);
struct media_pad *camss_find_sensor_pad(struct media_entity *entity);
s64 camss_get_link_freq(struct media_entity *entity, unsigned int bpp,
- unsigned int lanes);
+ unsigned int lanes, bool cphy);
int camss_get_pixel_clock(struct media_entity *entity, u64 *pixel_clock);
int camss_pm_domain_on(struct camss *camss, int id);
void camss_pm_domain_off(struct camss *camss, int id);
