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Date: Mon, 22 Jan 2024 13:14:09 +0100
From: Sascha Hauer <s.hauer@pengutronix.de>
To: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Cc: Vinod Koul <vkoul@kernel.org>,
	Kishon Vijay Abraham I <kishon@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Johan Jonker <jbx6244@gmail.com>,
	Sebastian Reichel <sebastian.reichel@collabora.com>,
	Andy Yan <andy.yan@rock-chips.com>,
	Algea Cao <algea.cao@rock-chips.com>, linux-phy@lists.infradead.org,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
	kernel@collabora.com
Subject: Re: [PATCH 3/3] phy: rockchip: Add Samsung HDMI/DP Combo PHY driver
Message-ID: <20240122121409.GW4700@pengutronix.de>
References: <20240119193806.1030214-1-cristian.ciocaltea@collabora.com>
 <20240119193806.1030214-4-cristian.ciocaltea@collabora.com>
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User-Agent: Mutt/1.10.1 (2018-07-13)

On Fri, Jan 19, 2024 at 09:38:03PM +0200, Cristian Ciocaltea wrote:
> Add driver for the Rockchip HDMI/eDP TX Combo PHY found on RK3588 SoC.
> 
> The PHY is based on a Samsung IP block and supports HDMI 2.1 TMDS, FRL
> and eDP links.  The maximum data rate is 12Gbps (HDMI 2.1 FRL), while
> the minimum is 250Mbps (HDMI 2.1 TMDS).
> 
> Co-developed-by: Algea Cao <algea.cao@rock-chips.com>
> Signed-off-by: Algea Cao <algea.cao@rock-chips.com>
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---
>  drivers/phy/rockchip/Kconfig                  |    8 +
>  drivers/phy/rockchip/Makefile                 |    1 +
>  .../phy/rockchip/phy-rockchip-samsung-hdptx.c | 2045 +++++++++++++++++
>  3 files changed, 2054 insertions(+)
>  create mode 100644 drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> 
> diff --git a/drivers/phy/rockchip/Kconfig b/drivers/phy/rockchip/Kconfig
> index 94360fc96a6f..95666ac6aa3b 100644
> --- a/drivers/phy/rockchip/Kconfig
> +++ b/drivers/phy/rockchip/Kconfig
> @@ -83,6 +83,14 @@ config PHY_ROCKCHIP_PCIE
>  	help
>  	  Enable this to support the Rockchip PCIe PHY.
>  
> +config PHY_ROCKCHIP_SAMSUNG_HDPTX
> +	tristate "Rockchip Samsung HDMI/DP Combo PHY driver"
> +	depends on (ARCH_ROCKCHIP || COMPILE_TEST) && OF
> +	select GENERIC_PHY
> +	help
> +	  Enable this to support the Rockchip HDMI/DP Combo PHY
> +	  with Samsung IP block.
> +
>  config PHY_ROCKCHIP_SNPS_PCIE3
>  	tristate "Rockchip Snps PCIe3 PHY Driver"
>  	depends on (ARCH_ROCKCHIP && OF) || COMPILE_TEST
> diff --git a/drivers/phy/rockchip/Makefile b/drivers/phy/rockchip/Makefile
> index 7eab129230d1..3d911304e654 100644
> --- a/drivers/phy/rockchip/Makefile
> +++ b/drivers/phy/rockchip/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_PHY_ROCKCHIP_INNO_HDMI)	+= phy-rockchip-inno-hdmi.o
>  obj-$(CONFIG_PHY_ROCKCHIP_INNO_USB2)	+= phy-rockchip-inno-usb2.o
>  obj-$(CONFIG_PHY_ROCKCHIP_NANENG_COMBO_PHY)	+= phy-rockchip-naneng-combphy.o
>  obj-$(CONFIG_PHY_ROCKCHIP_PCIE)		+= phy-rockchip-pcie.o
> +obj-$(CONFIG_PHY_ROCKCHIP_SAMSUNG_HDPTX)	+= phy-rockchip-samsung-hdptx.o
>  obj-$(CONFIG_PHY_ROCKCHIP_SNPS_PCIE3)	+= phy-rockchip-snps-pcie3.o
>  obj-$(CONFIG_PHY_ROCKCHIP_TYPEC)	+= phy-rockchip-typec.o
>  obj-$(CONFIG_PHY_ROCKCHIP_USB)		+= phy-rockchip-usb.o
> diff --git a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> new file mode 100644
> index 000000000000..d8171ea5ce2b
> --- /dev/null
> +++ b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> @@ -0,0 +1,2045 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2021-2022 Rockchip Electronics Co., Ltd.
> + * Copyright (c) 2024 Collabora Ltd.
> + *
> + * Author: Algea Cao <algea.cao@rock-chips.com>
> + * Author: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> + */
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/phy/phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/rational.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +
> +#define GRF_HDPTX_CON0			0x00
> +#define HDPTX_I_PLL_EN			BIT(7)
> +#define HDPTX_I_BIAS_EN			BIT(6)
> +#define HDPTX_I_BGR_EN			BIT(5)
> +#define GRF_HDPTX_STATUS		0x80
> +#define HDPTX_O_PLL_LOCK_DONE		BIT(3)
> +#define HDPTX_O_PHY_CLK_RDY		BIT(2)
> +#define HDPTX_O_PHY_RDY			BIT(1)
> +#define HDPTX_O_SB_RDY			BIT(0)
> +
> +#define CMN_REG0000			0x0000

These register names are not particularly helpful. Maybe use a

#define CMN_REG(x)			((x) * 4)

Instead?

> +
> +static int hdptx_lcpll_frl_mode_config(struct rockchip_hdptx_phy *hdptx,
> +				       u32 rate)
> +{
> +	u32 bit_rate = rate & DATA_RATE_MASK;
> +	u8 color_depth = (rate & COLOR_DEPTH_MASK) ? 1 : 0;
> +	const struct lcpll_config *cfg = lcpll_cfg;
> +
> +	for (; cfg->bit_rate != ~0; cfg++)
> +		if (bit_rate == cfg->bit_rate)
> +			break;

You could use ARRAY_SIZE() to iterate over the array and save the extra
entry at the end. Likewise for the other arrays used in the driver.

> +
> +	if (cfg->bit_rate == ~0)
> +		return -EINVAL;
> +

> +static int rockchip_hdptx_phy_power_on(struct phy *phy)
> +{
> +	struct rockchip_hdptx_phy *hdptx = phy_get_drvdata(phy);
> +	int bus_width = phy_get_bus_width(hdptx->phy);
> +	int bit_rate = bus_width & DATA_RATE_MASK;

What is going on here? bus_width is set to 8 in probe() using
phy_set_bus_width(), but the value you pull out of phy_get_bus_width()
is expected to contain the bit_rate and several other flags.

It looks like you are tunneling flags from some other driver using this
field. Isn't there a better way to accomplish this? If not, I think this
needs some explanation.

At least the variable should be renamed. it's called "bus_width" and it's
passed to functions like hdptx_lcpll_frl_mode_config() which has this
parameter named "rate" which is quite confusing.

Sascha

> +	int ret;
> +
> +	dev_dbg(hdptx->dev, "%s bus_width=%x rate=%d\n",
> +		__func__, bus_width, bit_rate);
> +
> +	ret = pm_runtime_resume_and_get(hdptx->dev);
> +	if (ret) {
> +		dev_err(hdptx->dev, "Failed to resume phy: %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (bus_width & HDMI_EARC_MASK)
> +		hdptx->earc_en = true;
> +	else
> +		hdptx->earc_en = false;
> +
> +	if (bus_width & HDMI_MODE_MASK) {
> +		if (bit_rate > 24000000)
> +			ret = hdptx_lcpll_frl_mode_config(hdptx, bus_width);
> +		else
> +			ret = hdptx_ropll_frl_mode_config(hdptx, bus_width);
> +	} else {
> +		ret = hdptx_ropll_tmds_mode_config(hdptx, bus_width);
> +	}
> +
> +	if (ret)
> +		pm_runtime_put(hdptx->dev);
> +
> +	return ret;
> +}
> +

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