From: David Heidelberg via B4 Relay <devnull+david.ixit.cz@kernel.org>
To: Robert Foss <rfoss@kernel.org>, Todor Tomov <todor.too@gmail.com>,
Bryan O'Donoghue <bryan.odonoghue@linaro.org>,
Bryan O'Donoghue <bod@kernel.org>,
Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Luca Weiss <luca.weiss@fairphone.com>,
Petr Hodina <phodina@protonmail.com>,
"Dr. Git" <drgitx@gmail.com>, Cory Keitz <ckeitz@amazon.com>,
Loic Poulain <loic.poulain@oss.qualcomm.com>,
Hans Verkuil <hverkuil@kernel.org>,
Nihal Kumar Gupta <nihal.gupta@oss.qualcomm.com>
Cc: Frank Li <Frank.Li@nxp.com>,
Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>,
Kieran Bingham <kbingham@kernel.org>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org,
David Heidelberg <david@ixit.cz>
Subject: [PATCH v9 8/9] media: qcom: camss: Account for C-PHY when calculating link frequency
Date: Wed, 17 Jun 2026 10:32:26 +0200 [thread overview]
Message-ID: <20260617-qcom-cphy-v9-8-83da8a8e4e44@ixit.cz> (raw)
In-Reply-To: <20260617-qcom-cphy-v9-0-83da8a8e4e44@ixit.cz>
From: David Heidelberg <david@ixit.cz>
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 <sakari.ailus@linux.intel.com>
Link: https://docs.kernel.org/driver-api/media/tx-rx.html#pixel-rate
Signed-off-by: David Heidelberg <david@ixit.cz>
---
drivers/media/platform/qcom/camss/camss-csid.c | 6 ++++--
drivers/media/platform/qcom/camss/camss-csiphy.c | 6 ++++--
drivers/media/platform/qcom/camss/camss.c | 15 +++++++++++++--
drivers/media/platform/qcom/camss/camss.h | 2 +-
4 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/drivers/media/platform/qcom/camss/camss-csid.c b/drivers/media/platform/qcom/camss/camss-csid.c
index bcc34ac9dd212..c8cb6f1a3d3bc 100644
--- a/drivers/media/platform/qcom/camss/camss-csid.c
+++ b/drivers/media/platform/qcom/camss/camss-csid.c
@@ -535,24 +535,26 @@ const struct csid_format_info *csid_get_fmt_entry(const struct csid_format_info
/*
* csid_set_clock_rates - Calculate and set clock rates on CSID module
* @csiphy: CSID device
*/
static int csid_set_clock_rates(struct csid_device *csid)
{
struct device *dev = csid->camss->dev;
const struct csid_format_info *fmt;
+ const bool cphy = (csid->phy.phy_sel == CSID_PHY_SEL_CPHY);
+
s64 link_freq;
int i, j;
int ret;
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);
+
+ link_freq = camss_get_link_freq(&csid->subdev.entity, fmt->bpp, csid->phy.lane_cnt, cphy);
if (link_freq < 0)
link_freq = 0;
for (i = 0; i < csid->nclocks; i++) {
struct camss_clock *clock = &csid->clock[i];
if (!strcmp(clock->name, "csi0") ||
!strcmp(clock->name, "csi1") ||
diff --git a/drivers/media/platform/qcom/camss/camss-csiphy.c b/drivers/media/platform/qcom/camss/camss-csiphy.c
index 539ac4888b608..a136cd27880a6 100644
--- a/drivers/media/platform/qcom/camss/camss-csiphy.c
+++ b/drivers/media/platform/qcom/camss/camss-csiphy.c
@@ -139,18 +139,19 @@ static int csiphy_set_clock_rates(struct csiphy_device *csiphy)
struct device *dev = csiphy->camss->dev;
s64 link_freq;
int i, j;
int ret;
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;
+ const 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);
if (link_freq < 0)
link_freq = 0;
for (i = 0; i < csiphy->nclocks; i++) {
struct camss_clock *clock = &csiphy->clock[i];
if (csiphy->rate_set[i]) {
u64 min_rate = link_freq / 4;
@@ -265,19 +266,20 @@ static int csiphy_set_power(struct v4l2_subdev *sd, int on)
static int csiphy_stream_on(struct csiphy_device *csiphy)
{
struct csiphy_config *cfg = &csiphy->cfg;
s64 link_freq;
u8 lane_mask = csiphy->res->hw_ops->get_lane_mask(&cfg->csi2->lane_cfg);
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;
+ const 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,
"Cannot get CSI2 transmitter's link frequency\n");
return -EINVAL;
}
if (csiphy->base_clk_mux) {
diff --git a/drivers/media/platform/qcom/camss/camss.c b/drivers/media/platform/qcom/camss/camss.c
index 072c428e25166..66171069057f8 100644
--- a/drivers/media/platform/qcom/camss/camss.c
+++ b/drivers/media/platform/qcom/camss/camss.c
@@ -27,16 +27,24 @@
#include <media/v4l2-mc.h>
#include <media/v4l2-fwnode.h>
#include "camss.h"
#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[] = {
/* CSIPHY0 */
{
.regulators = {},
.clock = { "top_ahb", "ispif_ahb", "ahb", "csiphy0_timer" },
.clock_rate = { { 0 },
@@ -4619,29 +4627,32 @@ 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
+ * @cphy: If C-PHY encoding is used.
*
* 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 lanes, const bool cphy)
{
struct media_pad *sensor_pad;
+ unsigned int div = 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);
}
/*
* camss_get_pixel_clock - Get pixel clock rate from sensor
* @entity: Media entity in the current pipeline
* @pixel_clock: Received pixel clock value
*
* Return 0 on success or a negative error code otherwise
diff --git a/drivers/media/platform/qcom/camss/camss.h b/drivers/media/platform/qcom/camss/camss.h
index 93d691c8ac63b..12b14ba8fcec3 100644
--- a/drivers/media/platform/qcom/camss/camss.h
+++ b/drivers/media/platform/qcom/camss/camss.h
@@ -164,17 +164,17 @@ struct parent_dev_ops {
};
void camss_add_clock_margin(u64 *rate);
int camss_enable_clocks(int nclocks, struct camss_clock *clock,
struct device *dev);
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, const 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);
int camss_vfe_get(struct camss *camss, int id);
void camss_vfe_put(struct camss *camss, int id);
void camss_delete(struct camss *camss);
void camss_buf_done(struct camss *camss, int hw_id, int port_id);
void camss_reg_update(struct camss *camss, int hw_id,
--
2.53.0
next prev parent reply other threads:[~2026-06-17 8:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-17 8:32 [PATCH v9 0/9] media: camss: Add support for C-PHY configuration on Qualcomm platforms David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 1/9] media: qcom: camss: csiphy-3ph: Fix lane mask calculation David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 2/9] media: qcom: camss: csiphy: Introduce PHY configuration David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 3/9] media: qcom: camss: csiphy-3ph: Use odd bits for configuring C-PHY lanes David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 4/9] media: qcom: camss: Prepare CSID for C-PHY support David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 5/9] media: qcom: camss: Initialize lanes after lane configuration is available David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 6/9] media: qcom: camss: csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 C-PHY init David Heidelberg via B4 Relay
2026-06-17 8:32 ` [PATCH v9 7/9] media: qcom: camss: csiphy-3ph: Update " David Heidelberg via B4 Relay
2026-06-17 8:32 ` David Heidelberg via B4 Relay [this message]
2026-06-17 8:32 ` [PATCH v9 9/9] media: qcom: camss: Enable C-PHY where available David Heidelberg via B4 Relay
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