Re: [PATCH v5 2/2] phy: qcom-mipi-csi2: Add a CSI2 MIPI DPHY driver

Abel Vesa
2026-04-06T14:28:49Z

On 26-03-26 01:04:44, Bryan O'Donoghue wrote:
> Add a new MIPI CSI2 driver in DPHY mode initially. The entire set of
> existing CAMSS CSI PHY init sequences are imported in order to save time
> and effort in later patches.
>
> The following devices are supported in this drop:
> "qcom,x1e80100-csi2-phy"
>
> In-line with other PHY drivers the process node is included in the name.
> Data-lane and clock lane positioning and polarity selection via newly
> amended struct phy_configure_opts_mipi_dphy{} is supported.
>
> The Qualcomm 3PH class of PHYs can do both DPHY and CPHY mode. For now only
> DPHY is supported.
>
> In porting some of the logic over from camss-csiphy*.c to here its also
> possible to rationalise some of the code.
>
> In particular use of regulator_bulk and clk_bulk as well as dropping the
> seemingly useless and unused interrupt handler.
>
> The PHY sequences and a lot of the logic that goes with them are well
> proven in CAMSS and mature so the main thing to watch out for here is how
> to get the right sequencing of regulators, clocks and register-writes.
>
> The register init sequence table is imported verbatim from the existing
> CAMSS csiphy driver. A follow-up series will rework the table to extract
> the repetitive per-lane pattern into a loop.
>
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
> ---
> MAINTAINERS | 11 +
> drivers/phy/qualcomm/Kconfig | 13 +
> drivers/phy/qualcomm/Makefile | 5 +
> drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c | 361 +++++++++++++++++++++
> drivers/phy/qualcomm/phy-qcom-mipi-csi2-core.c | 298 +++++++++++++++++
> drivers/phy/qualcomm/phy-qcom-mipi-csi2.h | 95 ++++++
> 6 files changed, 783 insertions(+)
>

[...]

> diff --git a/drivers/phy/qualcomm/phy-qcom-mipi-csi2-core.c b/drivers/phy/qualcomm/phy-qcom-mipi-csi2-core.c
> new file mode 100644
> index 0000000000000..47acf0d586a15
> --- /dev/null
> +++ b/drivers/phy/qualcomm/phy-qcom-mipi-csi2-core.c
> @@ -0,0 +1,298 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2025, Linaro Ltd.
> + */
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pm_opp.h>
> +#include <linux/phy/phy.h>
> +#include <linux/phy/phy-mipi-dphy.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/reset.h>
> +#include <linux/slab.h>
> +
> +#include <dt-bindings/phy/phy-qcom-mipi-csi2.h>
> +
> +#include "phy-qcom-mipi-csi2.h"
> +
> +static int
> +phy_qcom_mipi_csi2_set_clock_rates(struct mipi_csi2phy_device *csi2phy,
> + s64 link_freq)
> +{
> + struct device *dev = csi2phy->dev;
> + unsigned long opp_rate = link_freq / 4;
> + struct dev_pm_opp *opp;
> + long timer_rate;
> + int ret;
> +
> + opp = dev_pm_opp_find_freq_ceil(dev, &opp_rate);
> + if (IS_ERR(opp)) {
> + dev_err(csi2phy->dev, "Couldn't find ceiling for %lld Hz\n",
> + link_freq);
> + return PTR_ERR(opp);
> + }
> +
> + for (int i = 0; i < csi2phy->num_pds; i++) {
> + unsigned int perf = dev_pm_opp_get_required_pstate(opp, i);
> +
> + ret = dev_pm_genpd_set_performance_state(csi2phy->pds[i], perf);
> + if (ret) {
> + dev_err(csi2phy->dev, "Couldn't set perf state %u\n",
> + perf);
> + dev_pm_opp_put(opp);
> + return ret;
> + }
> + }
> + dev_pm_opp_put(opp);
> +
> + ret = dev_pm_opp_set_rate(dev, opp_rate);
> + if (ret) {
> + dev_err(csi2phy->dev, "dev_pm_opp_set_rate() fail\n");
> + return ret;
> + }
> +
> + timer_rate = clk_round_rate(csi2phy->timer_clk, link_freq / 4);
> + if (timer_rate < 0)
> + return timer_rate;
> +
> + ret = clk_set_rate(csi2phy->timer_clk, timer_rate);
> + if (ret)
> + return ret;
> +
> + csi2phy->timer_clk_rate = timer_rate;
> +
> + return 0;
> +}
> +
> +static int phy_qcom_mipi_csi2_configure(struct phy *phy,
> + union phy_configure_opts *opts)
> +{
> + struct mipi_csi2phy_device *csi2phy = phy_get_drvdata(phy);
> + struct phy_configure_opts_mipi_dphy *dphy_cfg = &opts->mipi_dphy;
> + struct mipi_csi2phy_stream_cfg *stream_cfg = &csi2phy->stream_cfg;
> + int ret;
> + int i;
> +
> + ret = phy_mipi_dphy_config_validate(dphy_cfg);
> + if (ret)
> + return ret;
> +
> + if (dphy_cfg->lanes < 1 || dphy_cfg->lanes > CSI2_MAX_DATA_LANES)
> + return -EINVAL;
> +
> + stream_cfg->link_freq = dphy_cfg->hs_clk_rate;
> + stream_cfg->num_data_lanes = dphy_cfg->lanes;
> +
> + for (i = 0; i < stream_cfg->num_data_lanes; i++) {
> + stream_cfg->lane_cfg.data[i].pol = dphy_cfg->lane_polarities[i];
> + stream_cfg->lane_cfg.data[i].pos = dphy_cfg->lane_positions[i];
> + }
> +
> + stream_cfg->lane_cfg.clk.pol = dphy_cfg->clock_lane_polarity;
> + stream_cfg->lane_cfg.clk.pos = dphy_cfg->clock_lane_position;
> +
> + return 0;
> +}
> +
> +static int phy_qcom_mipi_csi2_power_on(struct phy *phy)
> +{
> + struct mipi_csi2phy_device *csi2phy = phy_get_drvdata(phy);
> + const struct mipi_csi2phy_hw_ops *ops = csi2phy->soc_cfg->ops;
> + struct device *dev = &phy->dev;
> + int ret;
> +
> + ret = regulator_bulk_enable(csi2phy->soc_cfg->num_supplies,
> + csi2phy->supplies);
> + if (ret)
> + return ret;
> +
> + ret = phy_qcom_mipi_csi2_set_clock_rates(csi2phy, csi2phy->stream_cfg.link_freq);
> + if (ret)
> + goto poweroff_phy;
> +
> + ret = clk_bulk_prepare_enable(csi2phy->soc_cfg->num_clk,
> + csi2phy->clks);
> + if (ret) {
> + dev_err(dev, "failed to enable clocks, %d\n", ret);
> + goto poweroff_phy;
> + }
> +
> + ops->reset(csi2phy);
> +
> + ops->hw_version_read(csi2phy);
> +
> + return ops->lanes_enable(csi2phy, &csi2phy->stream_cfg);
> +
> +poweroff_phy:
> + regulator_bulk_disable(csi2phy->soc_cfg->num_supplies,
> + csi2phy->supplies);
> +
> + return ret;
> +}
> +
> +static int phy_qcom_mipi_csi2_power_off(struct phy *phy)
> +{
> + struct mipi_csi2phy_device *csi2phy = phy_get_drvdata(phy);
> + int i;
> +
> + for (i = 0; i < csi2phy->num_pds; i++)
> + dev_pm_genpd_set_performance_state(csi2phy->pds[i], 0);
> +
> + clk_bulk_disable_unprepare(csi2phy->soc_cfg->num_clk,
> + csi2phy->clks);
> + regulator_bulk_disable(csi2phy->soc_cfg->num_supplies,
> + csi2phy->supplies);
> +
> + return 0;
> +}
> +
> +static const struct phy_ops phy_qcom_mipi_csi2_ops = {
> + .configure = phy_qcom_mipi_csi2_configure,
> + .power_on = phy_qcom_mipi_csi2_power_on,
> + .power_off = phy_qcom_mipi_csi2_power_off,
> + .owner = THIS_MODULE,
> +};
> +
> +static struct phy *qcom_csi2_phy_xlate(struct device *dev,
> + const struct of_phandle_args *args)
> +{
> + struct mipi_csi2phy_device *csi2phy = dev_get_drvdata(dev);
> +
> + if (args->args[0] != PHY_QCOM_CSI2_MODE_DPHY) {
> + dev_err(csi2phy->dev, "mode %d -EOPNOTSUPP\n", args->args[0]);
> + return ERR_PTR(-EOPNOTSUPP);
> + }
> +
> + csi2phy->phy_mode = args->args[0];
> +
> + return csi2phy->phy;
> +}
> +
> +static int phy_qcom_mipi_csi2_probe(struct platform_device *pdev)
> +{
> + unsigned int i, num_clk, num_supplies, num_pds;
> + struct mipi_csi2phy_device *csi2phy;
> + struct phy_provider *phy_provider;
> + struct device *dev = &pdev->dev;
> + struct phy *generic_phy;
> + int ret;
> +
> + csi2phy = devm_kzalloc(dev, sizeof(*csi2phy), GFP_KERNEL);
> + if (!csi2phy)
> + return -ENOMEM;
> +
> + csi2phy->dev = dev;
> + dev_set_drvdata(dev, csi2phy);
> +
> + csi2phy->soc_cfg = device_get_match_data(&pdev->dev);
> +
> + if (!csi2phy->soc_cfg)
> + return -EINVAL;
> +
> + num_clk = csi2phy->soc_cfg->num_clk;
> + csi2phy->clks = devm_kzalloc(dev, sizeof(*csi2phy->clks) * num_clk, GFP_KERNEL);
> + if (!csi2phy->clks)
> + return -ENOMEM;
> +
> + num_pds = csi2phy->soc_cfg->num_genpd_names;
> + if (!num_pds)
> + return -EINVAL;
> +
> + csi2phy->pds = devm_kzalloc(dev, sizeof(*csi2phy->pds) * num_pds, GFP_KERNEL);
> + if (!csi2phy->pds)
> + return -ENOMEM;
> +
> + for (i = 0; i < num_pds; i++) {
> + csi2phy->pds[i] = dev_pm_domain_attach_by_name(dev,
> + csi2phy->soc_cfg->genpd_names[i]);

You need to do detach these on error, otherwise you get:

sysfs: cannot create duplicate filename '/devices/genpd:0:acec000.phy'
CPU: 1 UID: 0 PID: 93 Comm: kworker/u49:2 Not tainted 7.0.0-rc6-00062-gd691cf9ea708 #12 PREEMPT
Hardware name: Dell Inc. XPS 13 9345/05H2K4, BIOS 2.11.0 09/21/2025
Workqueue: events_unbound deferred_probe_work_func
show_stack+0x18/0x24 (C)
dump_stack_lvl+0x60/0x80
dump_stack+0x18/0x24
sysfs_warn_dup+0x64/0x80
sysfs_create_dir_ns+0xf4/0x120
kobject_add_internal+0x98/0x260
kobject_add+0x9c/0x108
device_add+0xc4/0x7ac
device_register+0x20/0x34
genpd_dev_pm_attach_by_id+0xdc/0x1cc
genpd_dev_pm_attach_by_name+0x3c/0x78
dev_pm_domain_attach_by_name+0x20/0x2c
phy_qcom_mipi_csi2_probe+0xe0/0x420 [phy_qcom_mipi_csi2]
platform_probe+0x5c/0xa4
really_probe+0xbc/0x2c0
__driver_probe_device+0x78/0x120
driver_probe_device+0x3c/0x154
__device_attach_driver+0xb8/0x140
bus_for_each_drv+0x88/0xe8
__device_attach+0xa0/0x190
device_initial_probe+0x50/0x54
bus_probe_device+0x38/0xac
device_add+0x5c4/0x7ac
of_device_add+0x44/0x60
of_platform_device_create_pdata+0x8c/0x11c
of_platform_bus_create+0x190/0x38c
of_platform_populate+0x74/0x108
devm_of_platform_populate+0x58/0xc0
camss_probe+0x3c/0xce0 [qcom_camss]
platform_probe+0x5c/0xa4
really_probe+0xbc/0x2c0
__driver_probe_device+0x78/0x120
driver_probe_device+0x3c/0x154
__device_attach_driver+0xb8/0x140
bus_for_each_drv+0x88/0xe8
__device_attach+0xa0/0x190
device_initial_probe+0x50/0x54
bus_probe_device+0x38/0xac
deferred_probe_work_func+0x90/0xc8
process_one_work+0x154/0x294
worker_thread+0x18c/0x300
kthread+0x118/0x124
ret_from_fork+0x10/0x20
kobject: kobject_add_internal failed for genpd:0:acec000.phy with -EEXIST, don't try to register things with the same name in the same directory.
qcom-mipi-csi2-phy acec000.phy: error -EEXIST: Failed to attach mx
qcom-mipi-csi2-phy acec000.phy: probe with driver qcom-mipi-csi2-phy failed with error -17