Hi Ezequiel,

On Tue, Jan 07, 2020 at 12:58:21PM -0300, Ezequiel Garcia wrote:

On Tue, 2020-01-07 at 03:11 +0200, Laurent Pinchart wrote:

quoted

On Fri, Dec 27, 2019 at 05:01:06PM -0300, Helen Koike wrote:

quoted

From: Ezequiel Garcia <redacted>

Add driver for Rockchip MIPI Synopsys DPHY driver

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Ezequiel Garcia <redacted>
Signed-off-by: Helen Koike <redacted>

---

Changes in v12:
- several cleanups
- remove "rx" from function names, as this driver only supports rx

Changes in v11:
- fix checkpatch errors

Changes in v10: None
Changes in v9:
- Move to staging
- replace memcpy by a directly assignment
- remove unecessary ret variable in rockchip_dphy_init
- s/0x1/1
- s/0x0/0
- coding style changes
- dphy_reg variable sizes
- variables from int to unsigned int
- rename functions to start with rk_
- rename dphy0 to rx
- fix hardcoded lane0 usage
- disable rx on power off
- general cleanups of unused variables

Changes in v8:
- Remove boiler plate license text

Changes in v7:
- Migrate dphy specific code from
drivers/media/platform/rockchip/isp1/mipi_dphy_sy.c
to drivers/phy/rockchip/phy-rockchip-dphy.c
- Drop support for rk3288
- Drop support for dphy txrx
- code styling and checkpatch fixes

 drivers/staging/media/Kconfig                 |   2 +
 drivers/staging/media/Makefile                |   1 +
 .../staging/media/phy-rockchip-dphy/Kconfig   |  11 +
 .../staging/media/phy-rockchip-dphy/Makefile  |   2 +
 drivers/staging/media/phy-rockchip-dphy/TODO  |   6 +
 .../phy-rockchip-dphy/phy-rockchip-dphy.c     | 396 ++++++++++++++++++
 6 files changed, 418 insertions(+)
 create mode 100644 drivers/staging/media/phy-rockchip-dphy/Kconfig
 create mode 100644 drivers/staging/media/phy-rockchip-dphy/Makefile
 create mode 100644 drivers/staging/media/phy-rockchip-dphy/TODO
 create mode 100644 drivers/staging/media/phy-rockchip-dphy/phy-rockchip-dphy.c

diff --git a/drivers/staging/media/Kconfig b/drivers/staging/media/Kconfig
index 642adc4c24d2..a47484473883 100644
--- a/drivers/staging/media/Kconfig
+++ b/drivers/staging/media/Kconfig

@@ -38,4 +38,6 @@ source "drivers/staging/media/ipu3/Kconfig"
 
 source "drivers/staging/media/soc_camera/Kconfig"
 
+source "drivers/staging/media/phy-rockchip-dphy/Kconfig"
+
 endif

diff --git a/drivers/staging/media/Makefile b/drivers/staging/media/Makefile
index 2f1711a8aeed..b0eae3906208 100644
--- a/drivers/staging/media/Makefile
+++ b/drivers/staging/media/Makefile

@@ -8,3 +8,4 @@ obj-$(CONFIG_TEGRA_VDE)		+= tegra-vde/
 obj-$(CONFIG_VIDEO_HANTRO)	+= hantro/
 obj-$(CONFIG_VIDEO_IPU3_IMGU)	+= ipu3/
 obj-$(CONFIG_SOC_CAMERA)	+= soc_camera/
+obj-$(CONFIG_PHY_ROCKCHIP_DPHY)		+= phy-rockchip-dphy/

diff --git a/drivers/staging/media/phy-rockchip-dphy/Kconfig b/drivers/staging/media/phy-rockchip-dphy/Kconfig
new file mode 100644
index 000000000000..7378bd75fa7c
--- /dev/null
+++ b/drivers/staging/media/phy-rockchip-dphy/Kconfig

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Phy drivers for Rockchip platforms

s/Phy/MIPI D-PHY/

Ack.

quoted

quoted

+#
+config PHY_ROCKCHIP_DPHY
+	tristate "Rockchip MIPI Synopsys DPHY driver"
+	depends on (ARCH_ROCKCHIP || COMPILE_TEST) && OF
+	select GENERIC_PHY_MIPI_DPHY
+	select GENERIC_PHY
+	help
+	  Enable this to support the Rockchip MIPI Synopsys DPHY.

diff --git a/drivers/staging/media/phy-rockchip-dphy/Makefile b/drivers/staging/media/phy-rockchip-dphy/Makefile
new file mode 100644
index 000000000000..24679dc950cd
--- /dev/null
+++ b/drivers/staging/media/phy-rockchip-dphy/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_PHY_ROCKCHIP_DPHY)		+= phy-rockchip-dphy.o

diff --git a/drivers/staging/media/phy-rockchip-dphy/TODO b/drivers/staging/media/phy-rockchip-dphy/TODO
new file mode 100644
index 000000000000..e1fda55babef
--- /dev/null
+++ b/drivers/staging/media/phy-rockchip-dphy/TODO

@@ -0,0 +1,6 @@
+The major reason for keeping this in staging is because the only driver

s/major/main/

What's wrong with "The major reason"?

I was under the impression you could say "A major reason" but not "The
major reason", but I could be wrong.

quoted

quoted

+who uses this is rkisp1 who is also in staging. It should be moved together

s/who uses this/that uses this/
s/who is also/, which is also/

quoted

+rkisp1.

s/rkisp1/with rkisp1/ ?

I see your point. Let me rephrase it.

quoted

quoted

+
+Please CC patches to Linux Media [off-list ref] and
+Helen Koike [off-list ref].

diff --git a/drivers/staging/media/phy-rockchip-dphy/phy-rockchip-dphy.c b/drivers/staging/media/phy-rockchip-dphy/phy-rockchip-dphy.c
new file mode 100644
index 000000000000..c3fe9c64b45f
--- /dev/null
+++ b/drivers/staging/media/phy-rockchip-dphy/phy-rockchip-dphy.c

@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)

Any reason for this ? Kernel code is usually GPL-2.0.

The ChromeOS driver is originally dual licensed,
so we tried to respect that.

That's up to you, but you can pick any license you want as long as it's
compatible with the original license. GPL-2.0 is a subset of GPL-2.0+ OR
MIT, so it would be fine. Of course you can't enforce a !MIT restriction
on the original code as you're not the copyright holder :-) But it may
make future contributions easier, as many people expect kernel code to
be licensed under GPL only. Furthermore the kernel binary compiled with
this driver included would have to be GPL-licensed anyway, so it's not
very useful to add a OR MIT.

quoted

quoted

+/*
+ * Rockchip MIPI Synopsys DPHY driver
+ *
+ * Copyright (C) 2019 Collabora, Ltd.
+ *
+ * Based on:
+ *
+ * drivers/media/platform/rockchip/isp1/mipi_dphy_sy.c
+ * in https://chromium.googlesource.com/chromiumos/third_party/kernel,
+ * chromeos-4.4 branch.
+ *
+ * Copyright (C) 2017 Fuzhou Rockchip Electronics Co., Ltd.
+ *   Jacob Chen [off-list ref]
+ *   Shunqian Zheng [off-list ref]
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/phy/phy.h>
+#include <linux/phy/phy-mipi-dphy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define RK3399_GRF_SOC_CON9		0x6224
+#define RK3399_GRF_SOC_CON21		0x6254
+#define RK3399_GRF_SOC_CON22		0x6258
+#define RK3399_GRF_SOC_CON23		0x625c
+#define RK3399_GRF_SOC_CON24		0x6260
+#define RK3399_GRF_SOC_CON25		0x6264
+#define RK3399_GRF_SOC_STATUS1		0xe2a4
+
+#define CLOCK_LANE_HS_RX_CONTROL	0x34
+#define LANE0_HS_RX_CONTROL		0x44
+#define LANE1_HS_RX_CONTROL		0x54
+#define LANE2_HS_RX_CONTROL		0x84
+#define LANE3_HS_RX_CONTROL		0x94
+#define LANES_THS_SETTLE_CONTROL	0x75
+#define THS_SETTLE_COUNTER_THRESHOLD	0x04
+
+struct hsfreq_range {
+	u16 range_h;
+	u8 cfg_bit;
+};
+
+static const struct hsfreq_range rk3399_mipidphy_hsfreq_ranges[] = {
+	{   89, 0x00 }, {   99, 0x10 }, {  109, 0x20 }, {  129, 0x01 },
+	{  139, 0x11 }, {  149, 0x21 }, {  169, 0x02 }, {  179, 0x12 },
+	{  199, 0x22 }, {  219, 0x03 }, {  239, 0x13 }, {  249, 0x23 },
+	{  269, 0x04 }, {  299, 0x14 }, {  329, 0x05 }, {  359, 0x15 },
+	{  399, 0x25 }, {  449, 0x06 }, {  499, 0x16 }, {  549, 0x07 },
+	{  599, 0x17 }, {  649, 0x08 }, {  699, 0x18 }, {  749, 0x09 },
+	{  799, 0x19 }, {  849, 0x29 }, {  899, 0x39 }, {  949, 0x0a },
+	{  999, 0x1a }, { 1049, 0x2a }, { 1099, 0x3a }, { 1149, 0x0b },
+	{ 1199, 0x1b }, { 1249, 0x2b }, { 1299, 0x3b }, { 1349, 0x0c },
+	{ 1399, 0x1c }, { 1449, 0x2c }, { 1500, 0x3c }
+};
+
+static const char * const rk3399_mipidphy_clks[] = {
+	"dphy-ref",
+	"dphy-cfg",
+	"grf",
+};
+
+enum dphy_reg_id {
+	GRF_DPHY_RX0_TURNDISABLE = 0,
+	GRF_DPHY_RX0_FORCERXMODE,
+	GRF_DPHY_RX0_FORCETXSTOPMODE,
+	GRF_DPHY_RX0_ENABLE,
+	GRF_DPHY_RX0_TESTCLR,
+	GRF_DPHY_RX0_TESTCLK,
+	GRF_DPHY_RX0_TESTEN,
+	GRF_DPHY_RX0_TESTDIN,
+	GRF_DPHY_RX0_TURNREQUEST,
+	GRF_DPHY_RX0_TESTDOUT,
+	GRF_DPHY_TX0_TURNDISABLE,
+	GRF_DPHY_TX0_FORCERXMODE,
+	GRF_DPHY_TX0_FORCETXSTOPMODE,
+	GRF_DPHY_TX0_TURNREQUEST,
+	GRF_DPHY_TX1RX1_TURNDISABLE,
+	GRF_DPHY_TX1RX1_FORCERXMODE,
+	GRF_DPHY_TX1RX1_FORCETXSTOPMODE,
+	GRF_DPHY_TX1RX1_ENABLE,
+	GRF_DPHY_TX1RX1_MASTERSLAVEZ,
+	GRF_DPHY_TX1RX1_BASEDIR,
+	GRF_DPHY_TX1RX1_ENABLECLK,
+	GRF_DPHY_TX1RX1_TURNREQUEST,
+	GRF_DPHY_RX1_SRC_SEL,
+	/* rk3288 only */
+	GRF_CON_DISABLE_ISP,
+	GRF_CON_ISP_DPHY_SEL,
+	GRF_DSI_CSI_TESTBUS_SEL,
+	GRF_DVP_V18SEL,
+	/* below is for rk3399 only */
+	GRF_DPHY_RX0_CLK_INV_SEL,
+	GRF_DPHY_RX1_CLK_INV_SEL,
+};
+
+struct dphy_reg {
+	u16 offset;
+	u8 mask;
+	u8 shift;
+};
+
+#define PHY_REG(_offset, _width, _shift) \
+	{ .offset = _offset, .mask = BIT(_width) - 1, .shift = _shift, }
+
+static const struct dphy_reg rk3399_grf_dphy_regs[] = {
+	[GRF_DPHY_RX0_TURNREQUEST] = PHY_REG(RK3399_GRF_SOC_CON9, 4, 0),
+	[GRF_DPHY_RX0_CLK_INV_SEL] = PHY_REG(RK3399_GRF_SOC_CON9, 1, 10),
+	[GRF_DPHY_RX1_CLK_INV_SEL] = PHY_REG(RK3399_GRF_SOC_CON9, 1, 11),
+	[GRF_DPHY_RX0_ENABLE] = PHY_REG(RK3399_GRF_SOC_CON21, 4, 0),
+	[GRF_DPHY_RX0_FORCERXMODE] = PHY_REG(RK3399_GRF_SOC_CON21, 4, 4),
+	[GRF_DPHY_RX0_FORCETXSTOPMODE] = PHY_REG(RK3399_GRF_SOC_CON21, 4, 8),
+	[GRF_DPHY_RX0_TURNDISABLE] = PHY_REG(RK3399_GRF_SOC_CON21, 4, 12),
+	[GRF_DPHY_TX0_FORCERXMODE] = PHY_REG(RK3399_GRF_SOC_CON22, 4, 0),
+	[GRF_DPHY_TX0_FORCETXSTOPMODE] = PHY_REG(RK3399_GRF_SOC_CON22, 4, 4),
+	[GRF_DPHY_TX0_TURNDISABLE] = PHY_REG(RK3399_GRF_SOC_CON22, 4, 8),
+	[GRF_DPHY_TX0_TURNREQUEST] = PHY_REG(RK3399_GRF_SOC_CON22, 4, 12),
+	[GRF_DPHY_TX1RX1_ENABLE] = PHY_REG(RK3399_GRF_SOC_CON23, 4, 0),
+	[GRF_DPHY_TX1RX1_FORCERXMODE] = PHY_REG(RK3399_GRF_SOC_CON23, 4, 4),
+	[GRF_DPHY_TX1RX1_FORCETXSTOPMODE] = PHY_REG(RK3399_GRF_SOC_CON23, 4, 8),
+	[GRF_DPHY_TX1RX1_TURNDISABLE] = PHY_REG(RK3399_GRF_SOC_CON23, 4, 12),
+	[GRF_DPHY_TX1RX1_TURNREQUEST] = PHY_REG(RK3399_GRF_SOC_CON24, 4, 0),
+	[GRF_DPHY_RX1_SRC_SEL] = PHY_REG(RK3399_GRF_SOC_CON24, 1, 4),
+	[GRF_DPHY_TX1RX1_BASEDIR] = PHY_REG(RK3399_GRF_SOC_CON24, 1, 5),
+	[GRF_DPHY_TX1RX1_ENABLECLK] = PHY_REG(RK3399_GRF_SOC_CON24, 1, 6),
+	[GRF_DPHY_TX1RX1_MASTERSLAVEZ] = PHY_REG(RK3399_GRF_SOC_CON24, 1, 7),
+	[GRF_DPHY_RX0_TESTDIN] = PHY_REG(RK3399_GRF_SOC_CON25, 8, 0),
+	[GRF_DPHY_RX0_TESTEN] = PHY_REG(RK3399_GRF_SOC_CON25, 1, 8),
+	[GRF_DPHY_RX0_TESTCLK] = PHY_REG(RK3399_GRF_SOC_CON25, 1, 9),
+	[GRF_DPHY_RX0_TESTCLR] = PHY_REG(RK3399_GRF_SOC_CON25, 1, 10),
+	[GRF_DPHY_RX0_TESTDOUT] = PHY_REG(RK3399_GRF_SOC_STATUS1, 8, 0),
+};
+
+struct rk_dphy_drv_data {
+	const char * const *clks;
+	unsigned int num_clks;
+	const struct hsfreq_range *hsfreq_ranges;
+	unsigned int num_hsfreq_ranges;
+	const struct dphy_reg *regs;
+};
+
+struct rk_dphy {
+	struct device *dev;
+	struct regmap *grf;
+	struct clk_bulk_data *clks;
+
+	const struct rk_dphy_drv_data *drv_data;
+	struct phy_configure_opts_mipi_dphy config;
+
+	u8 hsfreq;
+};
+
+static inline void rk_dphy_write_grf(struct rk_dphy *priv,
+				     unsigned int index, u8 value)
+{
+	const struct dphy_reg *reg = &priv->drv_data->regs[index];
+	/* Update high word */
+	unsigned int val = (value << reg->shift) |
+			   (reg->mask << (reg->shift + 16));
+
+	WARN_ON(!reg->offset);

Maybe

	if (WARN_ON(!reg->offset))
		return;

Right.

quoted

quoted

+	regmap_write(priv->grf, reg->offset, val);
+}
+
+static void rk_dphy_write(struct rk_dphy *priv,
+			  u8 test_code, u8 test_data)
+{
+	/*
+	 * With the falling edge on TESTCLK, the TESTDIN[7:0] signal content
+	 * is latched internally as the current test code. Test data is
+	 * programmed internally by rising edge on TESTCLK.
+	 */
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTCLK, 1);

Do we need this first line, as the function always exits with TESTCLK=1,
and TESTCLK is initialized to 1 before calling rk_dphy_write for the
first time ?

You might be right.

Perhaps we can test if it's fine to drop it, and put a comment
saying TESTCLK must be =1 here, so the assumption is clearly
stated.

Sounds good to me.

quoted

quoted

+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTDIN, test_code);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTEN, 1);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTCLK, 0);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTEN, 0);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTDIN, test_data);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTCLK, 1);
+}
+
+static void rk_dphy_enable(struct rk_dphy *priv)
+{
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_FORCERXMODE, 0);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_FORCETXSTOPMODE, 0);
+
+	/* Disable lane turn around, which is ignored in receive mode */
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TURNREQUEST, 0);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TURNDISABLE, 0xf);
+
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_ENABLE,
+			  GENMASK(priv->config.lanes - 1, 0));
+
+	/* dphy start */
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTCLK, 1);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTCLR, 1);
+	usleep_range(100, 150);
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_TESTCLR, 0);
+	usleep_range(100, 150);
+
+	/* set clock lane */
+	/* HS hsfreq_range & lane 0  settle bypass */
+	rk_dphy_write(priv, CLOCK_LANE_HS_RX_CONTROL, 0);
+	/* HS RX Control of lane0 */
+	rk_dphy_write(priv, LANE0_HS_RX_CONTROL, priv->hsfreq << 1);
+	/* HS RX Control of lane1 */
+	rk_dphy_write(priv, LANE1_HS_RX_CONTROL, priv->hsfreq << 1);
+	/* HS RX Control of lane2 */
+	rk_dphy_write(priv, LANE2_HS_RX_CONTROL, priv->hsfreq << 1);
+	/* HS RX Control of lane3 */
+	rk_dphy_write(priv, LANE3_HS_RX_CONTROL, priv->hsfreq << 1);
+	/* HS RX Data Lanes Settle State Time Control */
+	rk_dphy_write(priv, LANES_THS_SETTLE_CONTROL,
+		      THS_SETTLE_COUNTER_THRESHOLD);
+
+	/* Normal operation */
+	rk_dphy_write(priv, 0x0, 0);
+}
+
+static int rk_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
+{
+	struct rk_dphy *priv = phy_get_drvdata(phy);
+	const struct rk_dphy_drv_data *drv_data = priv->drv_data;
+	struct phy_configure_opts_mipi_dphy *config = &opts->mipi_dphy;
+	unsigned int i, hsfreq = 0, data_rate_mbps = config->hs_clk_rate;

Maybe one variable per line ?

Yeah.

quoted

quoted

+	int ret;
+
+	/* pass with phy_mipi_dphy_get_default_config (with pixel rate?) */
+	ret = phy_mipi_dphy_config_validate(config);
+	if (ret)
+		return ret;

I would add a blank line here.

quoted

+	do_div(data_rate_mbps, 1000 * 1000);

data_rate_mbps is an unsigned int, so you can use

	data_rate_mbps /= 1000 * 1000;

However, you're potentially truncating hs_clk_rate by assigning it to
data_rate_mbps, so I would remove the assignment at declaration time and
do

	data_rate_mbps = div_u64(config->hs_clk_rate, 1000 * 1000);

or define data_rate_mbps as an unsigned long.

Ah, good catch.

quoted

quoted

+
+	dev_dbg(priv->dev, "lanes %d - data_rate_mbps %u\n",
+		config->lanes, data_rate_mbps);
+	for (i = 0; i < drv_data->num_hsfreq_ranges; i++) {
+		if (drv_data->hsfreq_ranges[i].range_h >= data_rate_mbps) {
+			hsfreq = drv_data->hsfreq_ranges[i].cfg_bit;
+			break;
+		}
+	}
+	if (!hsfreq)
+		return -EINVAL;
+
+	priv->hsfreq = hsfreq;
+	priv->config = *config;
+	return 0;
+}
+
+static int rk_dphy_power_on(struct phy *phy)
+{
+	struct rk_dphy *priv = phy_get_drvdata(phy);
+	int ret;
+
+	ret = clk_bulk_enable(priv->drv_data->num_clks, priv->clks);
+	if (ret)
+		return ret;
+
+	rk_dphy_enable(priv);
+
+	return 0;
+}
+
+static int rk_dphy_power_off(struct phy *phy)
+{
+	struct rk_dphy *priv = phy_get_drvdata(phy);
+
+	rk_dphy_write_grf(priv, GRF_DPHY_RX0_ENABLE, 0);
+	clk_bulk_disable(priv->drv_data->num_clks, priv->clks);
+	return 0;
+}
+
+static int rk_dphy_init(struct phy *phy)
+{
+	struct rk_dphy *priv = phy_get_drvdata(phy);
+
+	return clk_bulk_prepare(priv->drv_data->num_clks, priv->clks);
+}
+
+static int rk_dphy_exit(struct phy *phy)
+{
+	struct rk_dphy *priv = phy_get_drvdata(phy);
+
+	clk_bulk_unprepare(priv->drv_data->num_clks, priv->clks);
+	return 0;
+}
+
+static const struct phy_ops rk_dphy_ops = {
+	.power_on	= rk_dphy_power_on,
+	.power_off	= rk_dphy_power_off,
+	.init		= rk_dphy_init,
+	.exit		= rk_dphy_exit,
+	.configure	= rk_dphy_configure,
+	.owner		= THIS_MODULE,
+};
+
+static const struct rk_dphy_drv_data rk3399_mipidphy_drv_data = {
+	.clks = rk3399_mipidphy_clks,
+	.num_clks = ARRAY_SIZE(rk3399_mipidphy_clks),
+	.hsfreq_ranges = rk3399_mipidphy_hsfreq_ranges,
+	.num_hsfreq_ranges = ARRAY_SIZE(rk3399_mipidphy_hsfreq_ranges),
+	.regs = rk3399_grf_dphy_regs,
+};
+
+static const struct of_device_id rk_dphy_dt_ids[] = {
+	{
+		.compatible = "rockchip,rk3399-mipi-dphy",
+		.data = &rk3399_mipidphy_drv_data,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, rk_dphy_dt_ids);
+
+static int rk_dphy_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	const struct rk_dphy_drv_data *drv_data;
+	struct phy_provider *phy_provider;
+	const struct of_device_id *of_id;
+	struct rk_dphy *priv;
+	struct regmap *grf;
+	struct phy *phy;
+	unsigned int i;
+	int ret;
+
+	if (!dev->parent || !dev->parent->of_node)
+		return -ENODEV;
+
+	if (platform_get_resource(pdev, IORESOURCE_MEM, 0)) {
+		dev_err(dev, "Rockchip DPHY driver only suports RX mode\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	priv->dev = dev;
+
+	grf = syscon_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(grf)) {
+		grf = syscon_regmap_lookup_by_phandle(dev->of_node,
+						      "rockchip,grf");

Is this for backward compatibility with older bindings ? Do we still
need it ? If so I would add a comment to explain why.

Right. I think this might end up being required, depending
on how the bindings end up loooking like.

quoted

With the above small issues fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

-- 
Regards,

Laurent Pinchart