linux-kernel - Re: [PATCH v5 2/5] phy: Add LVDS configuration options

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Date:   Wed, 31 Mar 2021 19:02:29 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Liu Ying <victor.liu@....com>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <vkoul@...nel.org>, <robh+dt@...nel.org>, <a.hajda@...sung.com>,
        <narmstrong@...libre.com>, <Laurent.pinchart@...asonboard.com>,
        <jonas@...boo.se>, <jernej.skrabec@...l.net>, <airlied@...ux.ie>,
        <daniel@...ll.ch>, <shawnguo@...nel.org>, <s.hauer@...gutronix.de>,
        <kernel@...gutronix.de>, <festevam@...il.com>, <linux-imx@....com>,
        <agx@...xcpu.org>, <robert.chiras@....com>,
        <martin.kepplinger@...i.sm>, <robert.foss@...aro.org>
Subject: Re: [PATCH v5 2/5] phy: Add LVDS configuration options

Hi,

On 25/03/21 2:30 pm, Liu Ying wrote:
> This patch allows LVDS PHYs to be configured through
> the generic functions and through a custom structure
> added to the generic union.
> 
> The parameters added here are based on common LVDS PHY
> implementation practices.  The set of parameters
> should cover all potential users.
> 
> Cc: Kishon Vijay Abraham I <kishon@...com>
> Cc: Vinod Koul <vkoul@...nel.org>
> Cc: NXP Linux Team <linux-imx@....com>
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
> v4->v5:
> * Align kernel-doc style to include/linux/phy/phy.h. (Vinod)
> * Trivial tweaks.
> * Drop Robert's R-b tag.
> 
> v3->v4:
> * Add Robert's R-b tag.
> 
> v2->v3:
> * No change.
> 
> v1->v2:
> * No change.
> 
>  include/linux/phy/phy-lvds.h | 32 ++++++++++++++++++++++++++++++++
>  include/linux/phy/phy.h      |  4 ++++
>  2 files changed, 36 insertions(+)
>  create mode 100644 include/linux/phy/phy-lvds.h
> 
> diff --git a/include/linux/phy/phy-lvds.h b/include/linux/phy/phy-lvds.h
> new file mode 100644
> index 00000000..7a2f474
> --- /dev/null
> +++ b/include/linux/phy/phy-lvds.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright 2020 NXP
> + */
> +
> +#ifndef __PHY_LVDS_H_
> +#define __PHY_LVDS_H_
> +
> +/**
> + * struct phy_configure_opts_lvds - LVDS configuration set
> + * @bits_per_lane_and_dclk_cycle:	Number of bits per data lane and
> + *					differential clock cycle.

phy_set_bus_width() instead?
> + * @differential_clk_rate:		Clock rate, in Hertz, of the LVDS
> + *					differential clock.

Please use clk API's to get rate.
> + * @lanes:				Number of active, consecutive,
> + *					data lanes, starting from lane 0,
> + *					used for the transmissions.
> + * @is_slave:				Boolean, true if the phy is a slave
> + *					which works together with a master
> + *					phy to support dual link transmission,
> + *					otherwise a regular phy or a master phy.

For parameters that are known at design time, it doesn't have to be
passed from consumer driver. So all these parameters do they really have
to be passed at runtime?

Thanks
Kishon
> + *
> + * This structure is used to represent the configuration state of a LVDS phy.
> + */
> +struct phy_configure_opts_lvds {
> +	unsigned int	bits_per_lane_and_dclk_cycle;
> +	unsigned long	differential_clk_rate;
> +	unsigned int	lanes;
> +	bool		is_slave;
> +};
> +
> +#endif /* __PHY_LVDS_H_ */
> diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> index e435bdb..d450b44 100644
> --- a/include/linux/phy/phy.h
> +++ b/include/linux/phy/phy.h
> @@ -17,6 +17,7 @@
>  #include <linux/regulator/consumer.h>
>  
>  #include <linux/phy/phy-dp.h>
> +#include <linux/phy/phy-lvds.h>
>  #include <linux/phy/phy-mipi-dphy.h>
>  
>  struct phy;
> @@ -51,10 +52,13 @@ enum phy_mode {
>   *		the MIPI_DPHY phy mode.
>   * @dp:		Configuration set applicable for phys supporting
>   *		the DisplayPort protocol.
> + * @lvds:	Configuration set applicable for phys supporting
> + *		the LVDS phy mode.
>   */
>  union phy_configure_opts {
>  	struct phy_configure_opts_mipi_dphy	mipi_dphy;
>  	struct phy_configure_opts_dp		dp;
> +	struct phy_configure_opts_lvds		lvds;
>  };
>  
>  /**
>