Re: [PATCH v2 3/4] drm: bridge: add it66121 driver

Laurent Pinchart
2020-03-12T00:53:42Z

Hi Andy,

On Wed, Mar 11, 2020 at 03:55:35PM +0200, Andy Shevchenko wrote:
> 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 ...

I didn't even know about those options... I don't think we can't expect
contributors to know about this if it's not even documented in
Documentation/process/. And even in that case, if this is what every
contribution should use by default, then those options should become the
default for the get_maintainer.pl script.

> ...
>
> > + * 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.
>
> > +};

--
Regards,

Laurent Pinchart