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Date:   Wed, 11 Mar 2020 15:55:35 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Phong LE <ple@baylibre.com>
Cc:     narmstrong@baylibre.com, airlied@linux.ie, daniel@ffwll.ch,
        robh+dt@kernel.org, mark.rutland@arm.com, a.hajda@samsung.com,
        Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se,
        jernej.skrabec@siol.net, sam@ravnborg.org, mripard@kernel.org,
        heiko.stuebner@theobroma-systems.com, linus.walleij@linaro.org,
        stephan@gerhold.net, icenowy@aosc.io, broonie@kernel.org,
        mchehab+samsung@kernel.org, davem@davemloft.net,
        gregkh@linuxfoundation.org, Jonathan.Cameron@huawei.com,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/4] drm: bridge: add it66121 driver
Message-ID: <20200311135535.GQ1922688@smile.fi.intel.com>
References: <20200311125135.30832-1-ple@baylibre.com>
 <20200311125135.30832-4-ple@baylibre.com>
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On Wed, Mar 11, 2020 at 01:51:34PM +0100, Phong LE wrote:
> This commit is a simple driver for bridge HMDI it66121.
> The input format is RBG and there is no color conversion.
> Audio, HDCP and CEC are not supported yet.

I guess you should have been told in your company how to use get_maintainer.pl
to avoid spamming people.

Hint:
	scripts/get_maintainer.pl --git --git-min-percent=67 ...

...

> + * Copyright (C) 2020 BayLibre, SAS
> + * Author: Phong LE <ple@baylibre.com>
> + * Copyright (C) 2018-2019, Artem Mygaiev
> + * Copyright (C) 2017, Fresco Logic, Incorporated.

This too compact to read, perhaps squeeze blank line after your (c) note
followed by description how the rest (c) appear in the file.

> + *

Redundant line.

> + */

...

> +#include <linux/of.h>

This can be replaced with property.h, see comments against ->probe().

> +#include <linux/of_device.h>
> +#include <linux/of_gpio.h>

I didn't find evidence of use of any of those.

...

> +#define IT66121_MASTER_SEL_REG			0x10

> +#define IT66121_AFE_DRV_REG			0x61

> +#define IT66121_INPUT_MODE_REG			0x70

> +#define IT66121_INPUT_CSC_REG			0x72

> +#define IT66121_AFE_XP_REG			0x62

> +#define IT66121_AFE_IP_REG			0x64

> +#define IT66121_AFE_XP_EC1_REG			0x68

> +#define IT66121_SW_RST_REG			0x04

> +#define IT66121_DDC_COMMAND_REG			0x15

> +#define IT66121_HDCP_REG			0x20

> +#define IT66121_INT_STATUS1_REG			0x06

> +#define IT66121_DDC_HEADER_REG			0x11

> +#define IT66121_DDC_OFFSET_REG			0x12
> +#define IT66121_DDC_BYTE_REG			0x13
> +#define IT66121_DDC_SEGMENT_REG			0x14
> +#define IT66121_DDC_RD_FIFO_REG			0x17

> +#define IT66121_CLK_BANK_REG			0x0F

> +#define IT66121_INT_REG				0x05

> +#define IT66121_INT_MASK1_REG			0x09

> +#define IT66121_INT_CLR1_REG			0x0C

> +#define IT66121_AV_MUTE_REG			0xC1

> +#define IT66121_PKT_GEN_CTRL_REG		0xC6

> +#define IT66121_AVIINFO_DB1_REG			0x158
> +#define IT66121_AVIINFO_DB2_REG			0x159
> +#define IT66121_AVIINFO_DB3_REG			0x15A
> +#define IT66121_AVIINFO_DB4_REG			0x15B
> +#define IT66121_AVIINFO_DB5_REG			0x15C
> +#define IT66121_AVIINFO_CSUM_REG		0x15D
> +#define IT66121_AVIINFO_DB6_REG			0x15E
> +#define IT66121_AVIINFO_DB7_REG			0x15F
> +#define IT66121_AVIINFO_DB8_REG			0x160
> +#define IT66121_AVIINFO_DB9_REG			0x161
> +#define IT66121_AVIINFO_DB10_REG		0x162
> +#define IT66121_AVIINFO_DB11_REG		0x163
> +#define IT66121_AVIINFO_DB12_REG		0x164
> +#define IT66121_AVIINFO_DB13_REG		0x165
> +
> +#define IT66121_AVI_INFO_PKT_REG		0xCD

> +#define IT66121_HDMI_MODE_REG			0xC0

> +#define IT66121_SYS_STATUS_REG			0x0E

> +#define IT66121_DDC_STATUS_REG			0x16

It's better to
a) keep register sorted by value (easy to be oriented);
b) have them in fixed width, e.g. 0x0CD.

...

> +#define IT66121_DEVICE_MASK			0x0F

GENMASK() ?

> +#define IT66121_EDID_SLEEP			20000
> +#define IT66121_EDID_TIMEOUT			200000

Care to add units?

> +#define IT66121_AFE_CLK_HIGH			80000

Also, what is the unit of this?

...

> +	return regmap_write(ctx->regmap, IT66121_MASTER_SEL_REG,
> +				IT66121_MASTER_SEL_HOST);

Indentation?
Same for other similar places.

...

> +static int it66121_configure_afe(struct it66121_ctx *ctx,
> +				 const struct drm_display_mode *mode)

...like this.

...

> +	if (val & (IT66121_DDC_STATUS_NOACK | IT66121_DDC_STATUS_WAIT_BUS |
> +	    IT66121_DDC_STATUS_ARBI_LOSE))
> +		return -EAGAIN;

Perhaps better to

	u32 busy = IT66121_DDC_STATUS_NOACK | IT66121_DDC_STATUS_WAIT_BUS |
		   IT66121_DDC_STATUS_ARBI_LOSE;


	if (val & busy)
		return -EAGAIN;

?

> +
> +	return 0;
> +}

...

> +static int it66121_abort_ddc_ops(struct it66121_ctx *ctx)
> +{
> +	int ret;
> +	unsigned int swreset, cpdesire;
> +
> +	ret = regmap_read(ctx->regmap, IT66121_SW_RST_REG, &swreset);
> +	if (ret)
> +		return ret;
> +

> +	ret = regmap_read(ctx->regmap, IT66121_HDCP_REG, &cpdesire);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(ctx->regmap, IT66121_HDCP_REG,
> +			   cpdesire & (~IT66121_HDCP_CPDESIRED & 0xFF));
> +	if (ret)
> +		return ret;

regmap_update_bits() ?

> +
> +	ret = regmap_write(ctx->regmap, IT66121_SW_RST_REG,
> +			   swreset | IT66121_SW_RST_HDCP);
> +	if (ret)
> +		return ret;

This should surround the inner update, correct? Otherwise, regmap_update_bits()
can be used as well.

> +}

...

> +static int it66121_get_edid_block(void *context, u8 *buf,
> +				  unsigned int block, size_t len)
> +{

> +		ret = regmap_write(ctx->regmap, IT66121_DDC_COMMAND_REG,
> +				   IT66121_DDC_COMMAND_EDID_READ);
> +		if (ret)
> +			return ret;
> +
> +		offset += cnt;
> +		remain -= cnt;

> +		msleep(20);

Should be explained.

> +
> +		ret = it66121_wait_ddc_ready(ctx);
> +		if (ret)
> +			return ret;
> +

> +		do {
> +			ret = regmap_read(ctx->regmap,
> +					  IT66121_DDC_RD_FIFO_REG, &val);
> +			if (ret)
> +				return ret;
> +			*(buf++) = val;
> +			cnt--;
> +		} while (cnt > 0);

I'm wondering if regmap API has a helper for above like cases.

> +	}
> +
> +	return 0;
> +}

...

> +static int it66121_connector_get_modes(struct drm_connector *connector)
> +{

> +	struct it66121_ctx *ctx = container_of(connector, struct it66121_ctx,
> +			connector);

Seems like it can be an inline helper and in all places you can use

	struct it66121_ctx *ctx = to_it66121_ctx(connector);


> +	ret = drm_connector_update_edid_property(connector,
> +						 ctx->edid);

It quite fits one line, perhaps configure your editor to see 80 limit sharp?
Applies to all similar cases as well.

> +	if (ret) {
> +		DRM_ERROR("Failed to update EDID property: %d\n", ret);
> +		goto unlock;
> +	}

> +}

...

> +	return (val & IT66121_SYS_STATUS_HPDETECT);

Too many parentheses.

...

> +	max_clock = ctx->dual_edge ? 74250 : 148500;

Magic numbers? Also, It seems one definition is enough.

...

> +	msleep(50);

Should be explained.

...

> +	val = mute ? IT66121_AV_MUTE_ON : (~IT66121_AV_MUTE_ON & 0xFF);

	val = mute ? IT66121_AV_MUTE_ON : 0;

> +	ret = regmap_write_bits(ctx->regmap, IT66121_AV_MUTE_REG,
> +				IT66121_AV_MUTE_ON, val);

...or even

	mask = IT66121_AV_MUTE_ON;
	val = mute ? mask : 0;

	ret = regmap_write_bits(ctx->regmap, IT66121_AV_MUTE_REG, mask, val);

> +	if (ret)
> +		return ret;

...

> +	regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
> +			  IT66121_CLK_BANK_PWROFF_TXCLK,
> +			  ~IT66121_CLK_BANK_PWROFF_TXCLK & 0xFF);

Same idea. What the point of all this operations in the value parameter?
Please, fix over the code.

...


> +	if (val & IT66121_SYS_STATUS_ACTIVE_IRQ) {

	if (!(val & IT66121_SYS_STATUS_ACTIVE_IRQ))
		goto unlock;

> +		ret = regmap_read(ctx->regmap, IT66121_INT_STATUS1_REG, &val);
> +		if (ret) {
> +			dev_err(dev, "Cannot read STATUS1_REG %d\n", ret);
> +		} else {
> +			if (val & IT66121_INT_STATUS1_DDC_FIFOERR)
> +				it66121_clear_ddc_fifo(ctx);

> +			if (val & (IT66121_INT_STATUS1_DDC_BUSHANG |
> +					IT66121_INT_STATUS1_DDC_NOACK))

Indentation.

> +				it66121_abort_ddc_ops(ctx);
> +			if (val & IT66121_INT_STATUS1_HPD_STATUS) {
> +				regmap_write_bits(ctx->regmap,
> +						  IT66121_INT_CLR1_REG,
> +						  IT66121_INT_CLR1_HPD,
> +						  IT66121_INT_CLR1_HPD);
> +
> +				if (!it66121_is_hpd_detect(ctx)) {
> +					kfree(ctx->edid);
> +					ctx->edid = NULL;
> +				}
> +				event = true;
> +			}
> +		}
> +
> +		regmap_write_bits(ctx->regmap, IT66121_SYS_STATUS_REG,
> +				  IT66121_SYS_STATUS_CLEAR_IRQ,
> +				  IT66121_SYS_STATUS_CLEAR_IRQ);
> +	}
> +
> +unlock:
> +	mutex_unlock(&ctx->lock);

...

> +static int it66121_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{

> +	u8 ids[4];

Magic, also see below.

> +	int i, ret;
> +	struct it66121_ctx *ctx;
> +	struct device *dev = &client->dev;

> +	ctx->conf = (struct it66121_conf *)of_device_get_match_data(dev);

device_get_match_data()

In any case why explicit casting?

> +	if (!ctx->conf)
> +		return -ENODEV;
> +

> +	ctx->dual_edge = of_property_read_bool(dev->of_node, "pclk-dual-edge");

device_property_read_bool()

> +	for (i = 0; i < 4; i++) {

Magic.

> +		regmap_read(ctx->regmap, i, &ret);
> +		ids[i] = ret;
> +	}

> +
> +	if (ids[0] != IT66121_VENDOR_ID0 ||
> +	    ids[1] != IT66121_VENDOR_ID1 ||
> +	    ids[2] != IT66121_DEVICE_ID0 ||
> +	    ((ids[3] & IT66121_DEVICE_MASK) != IT66121_DEVICE_ID1)) {
> +		ite66121_power_off(ctx);
> +		return -ENODEV;
> +	}
> +
> +	ctx->bridge.funcs = &it66121_bridge_funcs;
> +	ctx->bridge.of_node = dev->of_node;
> +
> +	ret = devm_request_threaded_irq(dev, client->irq, NULL,
> +					it66121_irq_threaded_handler,

> +					IRQF_SHARED | IRQF_TRIGGER_LOW |
> +					IRQF_ONESHOT,

Shouldn't flags come from appropriate resource provider (DT / ACPI / etc)?

> +					dev_name(dev),
> +					ctx);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to request irq %d:%d\n", client->irq, ret);
> +		ite66121_power_off(ctx);
> +		return ret;
> +	}
> +
> +	drm_bridge_add(&ctx->bridge);
> +
> +	return 0;
> +}

...

> +static const struct of_device_id it66121_dt_match[] = {
> +	{ .compatible = "ite,it66121",
> +	  .data = &it66121_conf_simple,
> +	},

> +	{ },

Terminator line doesn't need comma.

> +};

...

> +static const struct i2c_device_id it66121_id[] = {
> +	{ "it66121", 0 },

> +	{ },

Ditto.

> +};

-- 
With Best Regards,
Andy Shevchenko