Re: [PATCH v5 3/3] drm/bridge: chrontel-ch7033: Add a new driver

[Sam Ravnborg <sam@ravnborg.org>]

Hi Lubomir.

Drivers looks good. I look forward to the day we have moved
connector stuff to the displaydriver - this will simplify this driver
even more.

One Q in the following.

	Sam

On Fri, Apr 24, 2020 at 11:35:39PM +0200, Lubomir Rintel wrote:
> This is a driver for video encoder with VGA and DVI/HDMI outputs.
> 
> There is no documentation for the chip -- the operation was guessed from
> what was sniffed on a Dell Wyse 3020 ThinOS terminal, the register names
> come from the ch7035 driver in Mediatek's GPL code dump.
> 
> Only bare minimum is implemented -- no fancy stuff, such as scaling. That
> would only worsen our misery. We don't load the firmware and we don't need
> to even bother enabling the MCU.  There are probably no distributable
> firmware images anyway.
> 
> Tested with a handful of monitors ranging from 1024x768@75 to 1400x1050@60,
> with VGA as well as DVI.
> 
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
> 
> ---
> Changes since v4:
> - Removed the registration with the component framework and creation of
>   drm_encoder.
> 
> Changes since v3:
> - Cosmetic changes; drop ch7033_encoder_destroy() and use
>   drm_encoder_cleanup() for drm_encoder_funcs.destroy callback
>   directly.
> 
> Changes since v1:
> - Sort the includes
> - Drop a useless model id read
> - Chain to the bridge-connector instead of dealing with the HPD/EDID
>   readout machinery ourselves
> - Utilize regmap to access the registers
> 
>  drivers/gpu/drm/bridge/Kconfig           |  10 +
>  drivers/gpu/drm/bridge/Makefile          |   1 +
>  drivers/gpu/drm/bridge/chrontel-ch7033.c | 620 +++++++++++++++++++++++
>  3 files changed, 631 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/chrontel-ch7033.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index aaed2347ace9..0ebc72d62a5b 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -27,6 +27,16 @@ config DRM_CDNS_DSI
>  	  Support Cadence DPI to DSI bridge. This is an internal
>  	  bridge and is meant to be directly embedded in a SoC.
>  
> +config DRM_CHRONTEL_CH7033
> +	tristate "Chrontel CH7033 Video Encoder"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	help
> +	  Enable support for the Chrontel CH7033 VGA/DVI/HDMI Encoder, as
> +	  found in the Dell Wyse 3020 thin client.
> +
> +	  If in doubt, say "N".
> +
>  config DRM_DISPLAY_CONNECTOR
>  	tristate "Display connector support"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 6fb062b5b0f0..a844315feddb 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -1,5 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
> +obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
>  obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
> diff --git a/drivers/gpu/drm/bridge/chrontel-ch7033.c b/drivers/gpu/drm/bridge/chrontel-ch7033.c
> new file mode 100644
> index 000000000000..f8675d82974b
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/chrontel-ch7033.c
> @@ -0,0 +1,620 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Chrontel CH7033 Video Encoder Driver
> + *
> + * Copyright (C) 2019,2020 Lubomir Rintel
> + */
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +
> +/* Page 0, Register 0x07 */
> +enum {
> +	DRI_PD		= BIT(3),
> +	IO_PD		= BIT(5),
> +};
> +
> +/* Page 0, Register 0x08 */
> +enum {
> +	DRI_PDDRI	= GENMASK(7, 4),
> +	PDDAC		= GENMASK(3, 1),
> +	PANEN		= BIT(0),
> +};
> +
> +/* Page 0, Register 0x09 */
> +enum {
> +	DPD		= BIT(7),
> +	GCKOFF		= BIT(6),
> +	TV_BP		= BIT(5),
> +	SCLPD		= BIT(4),
> +	SDPD		= BIT(3),
> +	VGA_PD		= BIT(2),
> +	HDBKPD		= BIT(1),
> +	HDMI_PD		= BIT(0),
> +};
> +
> +/* Page 0, Register 0x0a */
> +enum {
> +	MEMINIT		= BIT(7),
> +	MEMIDLE		= BIT(6),
> +	MEMPD		= BIT(5),
> +	STOP		= BIT(4),
> +	LVDS_PD		= BIT(3),
> +	HD_DVIB		= BIT(2),
> +	HDCP_PD		= BIT(1),
> +	MCU_PD		= BIT(0),
> +};
> +
> +/* Page 0, Register 0x18 */
> +enum {
> +	IDF		= GENMASK(7, 4),
> +	INTEN		= BIT(3),
> +	SWAP		= GENMASK(2, 0),
> +};
> +
> +enum {
> +	BYTE_SWAP_RGB	= 0,
> +	BYTE_SWAP_RBG	= 1,
> +	BYTE_SWAP_GRB	= 2,
> +	BYTE_SWAP_GBR	= 3,
> +	BYTE_SWAP_BRG	= 4,
> +	BYTE_SWAP_BGR	= 5,
> +};
> +
> +/* Page 0, Register 0x19 */
> +enum {
> +	HPO_I		= BIT(5),
> +	VPO_I		= BIT(4),
> +	DEPO_I		= BIT(3),
> +	CRYS_EN		= BIT(2),
> +	GCLKFREQ	= GENMASK(2, 0),
> +};
> +
> +/* Page 0, Register 0x2e */
> +enum {
> +	HFLIP		= BIT(7),
> +	VFLIP		= BIT(6),
> +	DEPO_O		= BIT(5),
> +	HPO_O		= BIT(4),
> +	VPO_O		= BIT(3),
> +	TE		= GENMASK(2, 0),
> +};
> +
> +/* Page 0, Register 0x2b */
> +enum {
> +	SWAPS		= GENMASK(7, 4),
> +	VFMT		= GENMASK(3, 0),
> +};
> +
> +/* Page 0, Register 0x54 */
> +enum {
> +	COMP_BP		= BIT(7),
> +	DAC_EN_T	= BIT(6),
> +	HWO_HDMI_HI	= GENMASK(5, 3),
> +	HOO_HDMI_HI	= GENMASK(2, 0),
> +};
> +
> +/* Page 0, Register 0x57 */
> +enum {
> +	FLDSEN		= BIT(7),
> +	VWO_HDMI_HI	= GENMASK(5, 3),
> +	VOO_HDMI_HI	= GENMASK(2, 0),
> +};
> +
> +/* Page 0, Register 0x7e */
> +enum {
> +	HDMI_LVDS_SEL	= BIT(7),
> +	DE_GEN		= BIT(6),
> +	PWM_INDEX_HI	= BIT(5),
> +	USE_DE		= BIT(4),
> +	R_INT		= GENMASK(3, 0),
> +};
> +
> +/* Page 1, Register 0x07 */
> +enum {
> +	BPCKSEL		= BIT(7),
> +	DRI_CMFB_EN	= BIT(6),
> +	CEC_PUEN	= BIT(5),
> +	CEC_T		= BIT(3),
> +	CKINV		= BIT(2),
> +	CK_TVINV	= BIT(1),
> +	DRI_CKS2	= BIT(0),
> +};
> +
> +/* Page 1, Register 0x08 */
> +enum {
> +	DACG		= BIT(6),
> +	DACKTST		= BIT(5),
> +	DEDGEB		= BIT(4),
> +	SYO		= BIT(3),
> +	DRI_IT_LVDS	= GENMASK(2, 1),
> +	DISPON		= BIT(0),
> +};
> +
> +/* Page 1, Register 0x0c */
> +enum {
> +	DRI_PLL_CP	= GENMASK(7, 6),
> +	DRI_PLL_DIVSEL	= BIT(5),
> +	DRI_PLL_N1_1	= BIT(4),
> +	DRI_PLL_N1_0	= BIT(3),
> +	DRI_PLL_N3_1	= BIT(2),
> +	DRI_PLL_N3_0	= BIT(1),
> +	DRI_PLL_CKTSTEN = BIT(0),
> +};
> +
> +/* Page 1, Register 0x6b */
> +enum {
> +	VCO3CS		= GENMASK(7, 6),
> +	ICPGBK2_0	= GENMASK(5, 3),
> +	DRI_VCO357SC	= BIT(2),
> +	PDPLL2		= BIT(1),
> +	DRI_PD_SER	= BIT(0),
> +};
> +
> +/* Page 1, Register 0x6c */
> +enum {
> +	PLL2N11		= GENMASK(7, 4),
> +	PLL2N5_4	= BIT(3),
> +	PLL2N5_TOP	= BIT(2),
> +	DRI_PLL_PD	= BIT(1),
> +	PD_I2CM		= BIT(0),
> +};
> +
> +/* Page 3, Register 0x28 */
> +enum {
> +	DIFF_EN		= GENMASK(7, 6),
> +	CORREC_EN	= GENMASK(5, 4),
> +	VGACLK_BP	= BIT(3),
> +	HM_LV_SEL	= BIT(2),
> +	HD_VGA_SEL	= BIT(1),
> +};
> +
> +/* Page 3, Register 0x2a */
> +enum {
> +	LVDSCLK_BP	= BIT(7),
> +	HDTVCLK_BP	= BIT(6),
> +	HDMICLK_BP	= BIT(5),
> +	HDTV_BP		= BIT(4),
> +	HDMI_BP		= BIT(3),
> +	THRWL		= GENMASK(2, 0),
> +};
> +
> +/* Page 4, Register 0x52 */
> +enum {
> +	PGM_ARSTB	= BIT(7),
> +	MCU_ARSTB	= BIT(6),
> +	MCU_RETB	= BIT(2),
> +	RESETIB		= BIT(1),
> +	RESETDB		= BIT(0),
> +};
> +
> +struct ch7033_priv {
> +	struct regmap *regmap;
> +	struct drm_bridge *next_bridge;
> +	struct drm_bridge bridge;
> +	struct drm_connector connector;
> +};
> +
> +#define conn_to_ch7033_priv(x) \
> +	container_of(x, struct ch7033_priv, connector)
> +#define bridge_to_ch7033_priv(x) \
> +	container_of(x, struct ch7033_priv, bridge)
> +
> +
> +static enum drm_connector_status ch7033_connector_detect(
> +	struct drm_connector *connector, bool force)
> +{
> +	struct ch7033_priv *priv = conn_to_ch7033_priv(connector);
> +
> +	return drm_bridge_detect(priv->next_bridge);
> +}
> +
> +static const struct drm_connector_funcs ch7033_connector_funcs = {
> +	.reset = drm_atomic_helper_connector_reset,
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.detect = ch7033_connector_detect,
> +	.destroy = drm_connector_cleanup,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static int ch7033_connector_get_modes(struct drm_connector *connector)
> +{
> +	struct ch7033_priv *priv = conn_to_ch7033_priv(connector);
> +	struct edid *edid;
> +	int ret;
> +
> +	edid = drm_bridge_get_edid(priv->next_bridge, connector);

> +	drm_connector_update_edid_property(connector, edid);
I have seen that others do drm_connector_update_edid_property()
in the get_modes operation - but I am yet to understand why that
is correct in a get operation.
Maybe you know?


> +	if (edid) {
> +		ret = drm_add_edid_modes(connector, edid);
> +		kfree(edid);
> +	} else {
> +		ret = drm_add_modes_noedid(connector, 1920, 1080);
> +		drm_set_preferred_mode(connector, 1024, 768);
> +	}
> +
> +	return ret;
> +}
> +
> +static struct drm_encoder *ch7033_connector_best_encoder(
> +			struct drm_connector *connector)
> +{
> +	struct ch7033_priv *priv = conn_to_ch7033_priv(connector);
> +
> +	return priv->bridge.encoder;
> +}
> +
> +static const struct drm_connector_helper_funcs ch7033_connector_helper_funcs = {
> +	.get_modes = ch7033_connector_get_modes,
> +	.best_encoder = ch7033_connector_best_encoder,
> +};
> +
> +static void ch7033_hpd_event(void *arg, enum drm_connector_status status)
> +{
> +	struct ch7033_priv *priv = arg;
> +
> +	if (priv->bridge.dev)
> +		drm_helper_hpd_irq_event(priv->connector.dev);
> +}
> +
> +static int ch7033_bridge_attach(struct drm_bridge *bridge,
> +				enum drm_bridge_attach_flags flags)
> +{
> +	struct ch7033_priv *priv = bridge_to_ch7033_priv(bridge);
> +	struct drm_connector *connector = &priv->connector;
> +	int ret;
> +
> +	ret = drm_bridge_attach(bridge->encoder, priv->next_bridge, bridge,
> +				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +	if (ret)
> +		return ret;
> +
> +	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
> +		return 0;
> +
> +	if (priv->next_bridge->ops & DRM_BRIDGE_OP_DETECT) {
> +		connector->polled = DRM_CONNECTOR_POLL_HPD;
> +	} else {
> +		connector->polled = DRM_CONNECTOR_POLL_CONNECT |
> +				    DRM_CONNECTOR_POLL_DISCONNECT;
> +	}
> +
> +	if (priv->next_bridge->ops & DRM_BRIDGE_OP_HPD) {
> +		drm_bridge_hpd_enable(priv->next_bridge, ch7033_hpd_event,
> +				      priv);
> +	}
> +
> +	drm_connector_helper_add(connector,
> +				 &ch7033_connector_helper_funcs);
> +	ret = drm_connector_init_with_ddc(bridge->dev, &priv->connector,
> +					  &ch7033_connector_funcs,
> +					  priv->next_bridge->type,
> +					  priv->next_bridge->ddc);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialize connector\n");
> +		return ret;
> +	}
> +
> +	return drm_connector_attach_encoder(&priv->connector, bridge->encoder);
> +}
> +
> +static void ch7033_bridge_detach(struct drm_bridge *bridge)
> +{
> +	struct ch7033_priv *priv = bridge_to_ch7033_priv(bridge);
> +
> +	if (priv->next_bridge->ops & DRM_BRIDGE_OP_HPD)
> +		drm_bridge_hpd_disable(priv->next_bridge);
> +	drm_connector_cleanup(&priv->connector);
> +}
> +
> +static enum drm_mode_status ch7033_bridge_mode_valid(struct drm_bridge *bridge,
> +				     const struct drm_display_mode *mode)
> +{
> +	if (mode->clock > 165000)
> +		return MODE_CLOCK_HIGH;
> +	if (mode->hdisplay >= 1920)
> +		return MODE_BAD_HVALUE;
> +	if (mode->vdisplay >= 1080)
> +		return MODE_BAD_VVALUE;
> +	return MODE_OK;
> +}
> +
> +static void ch7033_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct ch7033_priv *priv = bridge_to_ch7033_priv(bridge);
> +
> +	regmap_write(priv->regmap, 0x03, 0x04);
> +	regmap_update_bits(priv->regmap, 0x52, RESETDB, 0x00);
> +}
> +
> +static void ch7033_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct ch7033_priv *priv = bridge_to_ch7033_priv(bridge);
> +
> +	regmap_write(priv->regmap, 0x03, 0x04);
> +	regmap_update_bits(priv->regmap, 0x52, RESETDB, RESETDB);
> +}
> +
> +static void ch7033_bridge_mode_set(struct drm_bridge *bridge,
> +				   const struct drm_display_mode *mode,
> +				   const struct drm_display_mode *adjusted_mode)
> +{
> +	struct ch7033_priv *priv = bridge_to_ch7033_priv(bridge);
> +	int hbporch = mode->hsync_start - mode->hdisplay;
> +	int hsynclen = mode->hsync_end - mode->hsync_start;
> +	int vbporch = mode->vsync_start - mode->vdisplay;
> +	int vsynclen = mode->vsync_end - mode->vsync_start;
> +
> +	/*
> +	 * Page 4
> +	 */
> +	regmap_write(priv->regmap, 0x03, 0x04);
> +
> +	/* Turn everything off to set all the registers to their defaults. */
> +	regmap_write(priv->regmap, 0x52, 0x00);
> +	/* Bring I/O block up. */
> +	regmap_write(priv->regmap, 0x52, RESETIB);
> +
> +	/*
> +	 * Page 0
> +	 */
> +	regmap_write(priv->regmap, 0x03, 0x00);
> +
> +	/* Bring up parts we need from the power down. */
> +	regmap_update_bits(priv->regmap, 0x07, DRI_PD | IO_PD, 0);
> +	regmap_update_bits(priv->regmap, 0x08, DRI_PDDRI | PDDAC | PANEN, 0);
> +	regmap_update_bits(priv->regmap, 0x09, DPD | GCKOFF |
> +					       HDMI_PD | VGA_PD, 0);
> +	regmap_update_bits(priv->regmap, 0x0a, HD_DVIB, 0);
> +
> +	/* Horizontal input timing. */
> +	regmap_write(priv->regmap, 0x0b, (mode->htotal >> 8) << 3 |
> +					 (mode->hdisplay >> 8));
> +	regmap_write(priv->regmap, 0x0c, mode->hdisplay);
> +	regmap_write(priv->regmap, 0x0d, mode->htotal);
> +	regmap_write(priv->regmap, 0x0e, (hsynclen >> 8) << 3 |
> +					 (hbporch >> 8));
> +	regmap_write(priv->regmap, 0x0f, hbporch);
> +	regmap_write(priv->regmap, 0x10, hsynclen);
> +
> +	/* Vertical input timing. */
> +	regmap_write(priv->regmap, 0x11, (mode->vtotal >> 8) << 3 |
> +					 (mode->vdisplay >> 8));
> +	regmap_write(priv->regmap, 0x12, mode->vdisplay);
> +	regmap_write(priv->regmap, 0x13, mode->vtotal);
> +	regmap_write(priv->regmap, 0x14, ((vsynclen >> 8) << 3) |
> +					 (vbporch >> 8));
> +	regmap_write(priv->regmap, 0x15, vbporch);
> +	regmap_write(priv->regmap, 0x16, vsynclen);
> +
> +	/* Input color swap. */
> +	regmap_update_bits(priv->regmap, 0x18, SWAP, BYTE_SWAP_BGR);
> +
> +	/* Input clock and sync polarity. */
> +	regmap_update_bits(priv->regmap, 0x19, 0x1, mode->clock >> 16);
> +	regmap_update_bits(priv->regmap, 0x19, HPO_I | VPO_I | GCLKFREQ,
> +			   (mode->flags & DRM_MODE_FLAG_PHSYNC) ? HPO_I : 0 |
> +			   (mode->flags & DRM_MODE_FLAG_PVSYNC) ? VPO_I : 0 |
> +			   mode->clock >> 16);
> +	regmap_write(priv->regmap, 0x1a, mode->clock >> 8);
> +	regmap_write(priv->regmap, 0x1b, mode->clock);
> +
> +	/* Horizontal output timing. */
> +	regmap_write(priv->regmap, 0x1f, (mode->htotal >> 8) << 3 |
> +					 (mode->hdisplay >> 8));
> +	regmap_write(priv->regmap, 0x20, mode->hdisplay);
> +	regmap_write(priv->regmap, 0x21, mode->htotal);
> +
> +	/* Vertical output timing. */
> +	regmap_write(priv->regmap, 0x25, (mode->vtotal >> 8) << 3 |
> +					 (mode->vdisplay >> 8));
> +	regmap_write(priv->regmap, 0x26, mode->vdisplay);
> +	regmap_write(priv->regmap, 0x27, mode->vtotal);
> +
> +	/* VGA channel bypass */
> +	regmap_update_bits(priv->regmap, 0x2b, VFMT, 9);
> +
> +	/* Output sync polarity. */
> +	regmap_update_bits(priv->regmap, 0x2e, HPO_O | VPO_O,
> +			   (mode->flags & DRM_MODE_FLAG_PHSYNC) ? HPO_O : 0 |
> +			   (mode->flags & DRM_MODE_FLAG_PVSYNC) ? VPO_O : 0);
> +
> +	/* HDMI horizontal output timing. */
> +	regmap_update_bits(priv->regmap, 0x54, HWO_HDMI_HI | HOO_HDMI_HI,
> +					       (hsynclen >> 8) << 3 |
> +					       (hbporch >> 8));
> +	regmap_write(priv->regmap, 0x55, hbporch);
> +	regmap_write(priv->regmap, 0x56, hsynclen);
> +
> +	/* HDMI vertical output timing. */
> +	regmap_update_bits(priv->regmap, 0x57, VWO_HDMI_HI | VOO_HDMI_HI,
> +					       (vsynclen >> 8) << 3 |
> +					       (vbporch >> 8));
> +	regmap_write(priv->regmap, 0x58, vbporch);
> +	regmap_write(priv->regmap, 0x59, vsynclen);
> +
> +	/* Pick HDMI, not LVDS. */
> +	regmap_update_bits(priv->regmap, 0x7e, HDMI_LVDS_SEL, HDMI_LVDS_SEL);
> +
> +	/*
> +	 * Page 1
> +	 */
> +	regmap_write(priv->regmap, 0x03, 0x01);
> +
> +	/* No idea what these do, but VGA is wobbly and blinky without them. */
> +	regmap_update_bits(priv->regmap, 0x07, CKINV, CKINV);
> +	regmap_update_bits(priv->regmap, 0x08, DISPON, DISPON);
> +
> +	/* DRI PLL */
> +	regmap_update_bits(priv->regmap, 0x0c, DRI_PLL_DIVSEL, DRI_PLL_DIVSEL);
> +	if (mode->clock <= 40000) {
> +		regmap_update_bits(priv->regmap, 0x0c, DRI_PLL_N1_1 |
> +						       DRI_PLL_N1_0 |
> +						       DRI_PLL_N3_1 |
> +						       DRI_PLL_N3_0,
> +						       0);
> +	} else if (mode->clock < 80000) {
> +		regmap_update_bits(priv->regmap, 0x0c, DRI_PLL_N1_1 |
> +						       DRI_PLL_N1_0 |
> +						       DRI_PLL_N3_1 |
> +						       DRI_PLL_N3_0,
> +						       DRI_PLL_N3_0 |
> +						       DRI_PLL_N1_0);
> +	} else {
> +		regmap_update_bits(priv->regmap, 0x0c, DRI_PLL_N1_1 |
> +						       DRI_PLL_N1_0 |
> +						       DRI_PLL_N3_1 |
> +						       DRI_PLL_N3_0,
> +						       DRI_PLL_N3_1 |
> +						       DRI_PLL_N1_1);
> +	}
> +
> +	/* This seems to be color calibration for VGA. */
> +	regmap_write(priv->regmap, 0x64, 0x29); /* LSB Blue */
> +	regmap_write(priv->regmap, 0x65, 0x29); /* LSB Green */
> +	regmap_write(priv->regmap, 0x66, 0x29); /* LSB Red */
> +	regmap_write(priv->regmap, 0x67, 0x00); /* MSB Blue */
> +	regmap_write(priv->regmap, 0x68, 0x00); /* MSB Green */
> +	regmap_write(priv->regmap, 0x69, 0x00); /* MSB Red */
> +
> +	regmap_update_bits(priv->regmap, 0x6b, DRI_PD_SER, 0x00);
> +	regmap_update_bits(priv->regmap, 0x6c, DRI_PLL_PD, 0x00);
> +
> +	/*
> +	 * Page 3
> +	 */
> +	regmap_write(priv->regmap, 0x03, 0x03);
> +
> +	/* More bypasses and apparently another HDMI/LVDS selector. */
> +	regmap_update_bits(priv->regmap, 0x28, VGACLK_BP | HM_LV_SEL,
> +					       VGACLK_BP | HM_LV_SEL);
> +	regmap_update_bits(priv->regmap, 0x2a, HDMICLK_BP | HDMI_BP,
> +					       HDMICLK_BP | HDMI_BP);
> +
> +	/*
> +	 * Page 4
> +	 */
> +	regmap_write(priv->regmap, 0x03, 0x04);
> +
> +	/* Output clock. */
> +	regmap_write(priv->regmap, 0x10, mode->clock >> 16);
> +	regmap_write(priv->regmap, 0x11, mode->clock >> 8);
> +	regmap_write(priv->regmap, 0x12, mode->clock);
> +}
> +
> +static const struct drm_bridge_funcs ch7033_bridge_funcs = {
> +	.attach = ch7033_bridge_attach,
> +	.detach = ch7033_bridge_detach,
> +	.mode_valid = ch7033_bridge_mode_valid,
> +	.disable = ch7033_bridge_disable,
> +	.enable = ch7033_bridge_enable,
> +	.mode_set = ch7033_bridge_mode_set,
> +};
> +
> +static const struct regmap_config ch7033_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = 0x7f,
> +};
> +
> +static int ch7033_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct ch7033_priv *priv;
> +	unsigned int val;
> +	int ret;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	dev_set_drvdata(dev, priv);
> +
> +	ret = drm_of_find_panel_or_bridge(dev->of_node, 1, -1, NULL,
> +					  &priv->next_bridge);
> +	if (ret)
> +		return ret;
> +
> +	priv->regmap = devm_regmap_init_i2c(client, &ch7033_regmap_config);
> +	if (IS_ERR(priv->regmap)) {
> +		dev_err(&client->dev, "regmap init failed\n");
> +		return PTR_ERR(priv->regmap);
> +	}
> +
> +	ret = regmap_read(priv->regmap, 0x00, &val);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "error reading the model id: %d\n", ret);
> +		return ret;
> +	}
> +	if ((val & 0xf7) != 0x56) {
> +		dev_err(&client->dev, "the device is not a ch7033\n");
> +		return -ENODEV;
> +	}
> +
> +	regmap_write(priv->regmap, 0x03, 0x04);
> +	ret = regmap_read(priv->regmap, 0x51, &val);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "error reading the model id: %d\n", ret);
> +		return ret;
> +	}
> +	if ((val & 0x0f) != 3) {
> +		dev_err(&client->dev, "unknown revision %u\n", val);
> +		return -ENODEV;
> +	}
> +
> +	INIT_LIST_HEAD(&priv->bridge.list);
> +	priv->bridge.funcs = &ch7033_bridge_funcs;
> +	priv->bridge.of_node = dev->of_node;
> +	drm_bridge_add(&priv->bridge);
> +
> +	dev_info(dev, "Chrontel CH7033 Video Encoder\n");
> +	return 0;
> +}
> +
> +static int ch7033_remove(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct ch7033_priv *priv = dev_get_drvdata(dev);
> +
> +	drm_bridge_remove(&priv->bridge);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ch7033_dt_ids[] = {
> +	{ .compatible = "chrontel,ch7033", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ch7033_dt_ids);
> +
> +static const struct i2c_device_id ch7033_ids[] = {
> +	{ "ch7033", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, ch7033_ids);
> +
> +static struct i2c_driver ch7033_driver = {
> +	.probe = ch7033_probe,
> +	.remove = ch7033_remove,
> +	.driver = {
> +		.name = "ch7033",
> +		.of_match_table = of_match_ptr(ch7033_dt_ids),
> +	},
> +	.id_table = ch7033_ids,
> +};
> +
> +module_i2c_driver(ch7033_driver);
> +
> +MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
> +MODULE_DESCRIPTION("Chrontel CH7033 Video Encoder Driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.26.0
> 
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