From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
To: david@ixit.cz, Robert Foss <rfoss@kernel.org>,
Todor Tomov <todor.too@gmail.com>,
Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Luca Weiss <luca.weiss@fairphone.com>,
Petr Hodina <phodina@protonmail.com>,
Casey Connolly <casey.connolly@linaro.org>,
"Dr. Git" <drgitx@gmail.com>
Cc: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>,
Joel Selvaraj <foss@joelselvaraj.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
Subject: Re: [PATCH WIP v4 9/9] media: qcom: camss: Account for C-PHY when calculating link frequency
Date: Tue, 3 Mar 2026 10:07:43 +0000 [thread overview]
Message-ID: <1fca6458-761d-446f-9223-7875a4a66f4f@linaro.org> (raw)
In-Reply-To: <20260301-qcom-cphy-v4-9-e53316d2cc65@ixit.cz>
On 01/03/2026 00:51, David Heidelberg via B4 Relay wrote:
> 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>
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
> drivers/media/platform/qcom/camss/camss-csid.c | 11 +++++++----
> drivers/media/platform/qcom/camss/camss-csiphy.c | 6 ++----
> drivers/media/platform/qcom/camss/camss.c | 18 +++++++++++++++---
> drivers/media/platform/qcom/camss/camss.h | 2 +-
> 4 files changed, 25 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/platform/qcom/camss/camss-csid.c b/drivers/media/platform/qcom/camss/camss-csid.c
> index b50b0cfe280c1..2fc17c6a15e2e 100644
> --- a/drivers/media/platform/qcom/camss/camss-csid.c
> +++ b/drivers/media/platform/qcom/camss/camss-csid.c
> @@ -534,18 +534,21 @@ 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)
> +static int csid_set_clock_rates(struct v4l2_subdev *sd, struct csid_device *csid)
> {
> struct device *dev = csid->camss->dev;
> + struct csiphy_device *csiphy = v4l2_get_subdevdata(sd);
> + struct csiphy_lanes_cfg *lane_cfg = &csiphy->cfg.csi2->lane_cfg;
> const struct csid_format_info *fmt;
> +
> 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, lane_cfg);
> if (link_freq < 0)
> link_freq = 0;
>
> @@ -703,7 +706,7 @@ static int csid_set_power(struct v4l2_subdev *sd, int on)
> return ret;
> }
>
> - ret = csid_set_clock_rates(csid);
> + ret = csid_set_clock_rates(sd, csid);
> if (ret < 0) {
> regulator_bulk_disable(csid->num_supplies,
> csid->supplies);
> diff --git a/drivers/media/platform/qcom/camss/camss-csiphy.c b/drivers/media/platform/qcom/camss/camss-csiphy.c
> index 938600f3defe1..ea9dd2cd2e740 100644
> --- a/drivers/media/platform/qcom/camss/camss-csiphy.c
> +++ b/drivers/media/platform/qcom/camss/camss-csiphy.c
> @@ -143,9 +143,8 @@ 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;
>
> - link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, num_lanes);
> + link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, &csiphy->cfg.csi2->lane_cfg);
> if (link_freq < 0)
> link_freq = 0;
>
> @@ -270,10 +269,9 @@ static int csiphy_stream_on(struct csiphy_device *csiphy)
> 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;
> u8 val;
>
> - link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, num_lanes);
> + link_freq = camss_get_link_freq(&csiphy->subdev.entity, bpp, &csiphy->cfg.csi2->lane_cfg);
>
> 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..4c13bae17007e 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 +4288,24 @@ 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
> + * @lane_cfg: CSI2 lane configuration
> *
> * 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)
> + struct csiphy_lanes_cfg *lane_cfg)
> {
> struct media_pad *sensor_pad;
> + u8 num_lanes = lane_cfg->num_data;
> + bool cphy = lane_cfg->phy_cfg == V4L2_MBUS_CSI2_CPHY;
> + unsigned int div = num_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..67be42b4c9174 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);
> + struct csiphy_lanes_cfg *lane_cfg);
> 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);
>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
next prev parent reply other threads:[~2026-03-03 10:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-01 0:51 [PATCH WIP v4 0/9] media: camss: Add support for C-PHY configuration on Qualcomm platforms David Heidelberg via B4 Relay
2026-03-01 0:51 ` [PATCH WIP v4 1/9] media: qcom: camss: csiphy: Introduce PHY configuration David Heidelberg via B4 Relay
2026-03-03 9:48 ` Bryan O'Donoghue
2026-03-01 0:51 ` [PATCH WIP v4 2/9] media: qcom: camss: csiphy-3ph: Use odd bits for configuring C-PHY lanes David Heidelberg via B4 Relay
2026-03-03 9:52 ` Bryan O'Donoghue
2026-03-01 0:51 ` [PATCH WIP v4 3/9] media: qcom: camss: Prepare CSID for C-PHY support David Heidelberg via B4 Relay
2026-03-03 9:53 ` Bryan O'Donoghue
2026-03-03 20:31 ` David Heidelberg
2026-03-01 0:51 ` [PATCH WIP v4 4/9] media: qcom: camss: Initialize lanes after lane configuration is available David Heidelberg via B4 Relay
2026-03-03 9:54 ` Bryan O'Donoghue
2026-03-03 10:06 ` David Heidelberg
2026-03-03 10:10 ` Bryan O'Donoghue
2026-03-03 10:12 ` David Heidelberg
2026-03-01 0:51 ` [PATCH WIP v4 5/9] media: qcom: camss: csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 CPHY init David Heidelberg via B4 Relay
2026-03-01 0:51 ` [PATCH WIP v4 6/9] media: qcom: camss: csiphy-3ph: Update " David Heidelberg via B4 Relay
2026-03-03 9:55 ` Bryan O'Donoghue
2026-03-03 10:00 ` David Heidelberg
2026-03-03 10:08 ` Bryan O'Donoghue
2026-03-03 10:22 ` Konrad Dybcio
2026-03-03 10:27 ` David Heidelberg
2026-03-03 10:39 ` Bryan O'Donoghue
2026-03-03 10:46 ` Konrad Dybcio
2026-03-01 0:51 ` [PATCH WIP v4 7/9] media: qcom: camss: csiphy-3ph: Add Gen2 v1.2.1 MIPI CSI-2 C-PHY init David Heidelberg via B4 Relay
2026-03-03 9:56 ` Bryan O'Donoghue
2026-03-01 0:51 ` [PATCH WIP v4 8/9] media: qcom: camss: csiphy-3ph: C-PHY needs own lane configuration David Heidelberg via B4 Relay
2026-03-03 9:59 ` Bryan O'Donoghue
2026-03-01 0:51 ` [PATCH WIP v4 9/9] media: qcom: camss: Account for C-PHY when calculating link frequency David Heidelberg via B4 Relay
2026-03-03 10:07 ` Bryan O'Donoghue [this message]
2026-03-20 19:48 ` Cory Keitz
2026-03-02 18:43 ` [PATCH WIP v4 0/9] media: camss: Add support for C-PHY configuration on Qualcomm platforms Cory Keitz
2026-03-02 23:13 ` David Heidelberg
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1fca6458-761d-446f-9223-7875a4a66f4f@linaro.org \
--to=bryan.odonoghue@linaro.org \
--cc=casey.connolly@linaro.org \
--cc=david@ixit.cz \
--cc=drgitx@gmail.com \
--cc=foss@joelselvaraj.com \
--cc=kbingham@kernel.org \
--cc=konrad.dybcio@oss.qualcomm.com \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=luca.weiss@fairphone.com \
--cc=mchehab@kernel.org \
--cc=phodina@protonmail.com \
--cc=phone-devel@vger.kernel.org \
--cc=rfoss@kernel.org \
--cc=sakari.ailus@linux.intel.com \
--cc=todor.too@gmail.com \
--cc=vladimir.zapolskiy@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox