linux-kernel - Re: [PATCH v2 01/14] phy: hdmi: Add HDMI 2.1 FRL configuration options

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Message-ID: <3d796f6c-d1d0-4499-8e63-bd37bfcc7c3a@oss.qualcomm.com>
Date: Sat, 16 Aug 2025 01:23:00 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
        Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Heiko Stuebner <heiko@...ech.de>, Algea Cao <algea.cao@...k-chips.com>,
        Dmitry Baryshkov <lumag@...nel.org>
Cc: kernel@...labora.com, linux-phy@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v2 01/14] phy: hdmi: Add HDMI 2.1 FRL configuration
 options

On 05/08/2025 14:56, Cristian Ciocaltea wrote:
> Add support for configuring the Fixed Rate Link (FRL) mode for HDMI
> PHYs.
> 
> For improved clarity, also rename existing HDMI mode to HDMI_TMDS.
> Since this mode is currently not being used explicitly, no further
> changes are needed.


I'd say, this need some explanation, especially for those who don't have 
access to the HDMI standard. Please mention that FRL is an alternative 
to the traditional TMDS mode, etc.

> 
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
> ---
>   include/linux/phy/phy-hdmi.h | 14 ++++++++++++--
>   include/linux/phy/phy.h      |  3 ++-
>   2 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/phy/phy-hdmi.h b/include/linux/phy/phy-hdmi.h
> index f0ec963c6e84f1b7728acafc824dff191c6b873d..0b26472d8defcc9ded142d4283e29861dc2b3746 100644
> --- a/include/linux/phy/phy-hdmi.h
> +++ b/include/linux/phy/phy-hdmi.h
> @@ -6,16 +6,26 @@
>   #ifndef __PHY_HDMI_H_
>   #define __PHY_HDMI_H_
>   
> +#include <linux/types.h>
> +
>   /**
>    * struct phy_configure_opts_hdmi - HDMI configuration set
> - * @tmds_char_rate: HDMI TMDS Character Rate in Hertz.
>    * @bpc: Bits per color channel.
> + * @tmds_char_rate: HDMI TMDS Character Rate in Hertz.
> + * @frl.rate_per_lane: HDMI FRL Rate per Lane in Gbps.
> + * @frl.lanes: HDMI FRL lanes count.
>    *
>    * This structure is used to represent the configuration state of a HDMI phy.
>    */
>   struct phy_configure_opts_hdmi {
> -	unsigned long long tmds_char_rate;
>   	unsigned int bpc;
> +	union {
> +		unsigned long long tmds_char_rate;
> +		struct {
> +			u8 rate_per_lane;
> +			u8 lanes;
> +		} frl;
> +	};
>   };
>   
>   #endif /* __PHY_HDMI_H_ */
> diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> index 13add0c2c40721fe9ca3f0350d13c035cd25af45..04c84c1dbd6dac55fd04c54203cff4f9d939d970 100644
> --- a/include/linux/phy/phy.h
> +++ b/include/linux/phy/phy.h
> @@ -44,7 +44,8 @@ enum phy_mode {
>   	PHY_MODE_SATA,
>   	PHY_MODE_LVDS,
>   	PHY_MODE_DP,
> -	PHY_MODE_HDMI,
> +	PHY_MODE_HDMI_TMDS,
> +	PHY_MODE_HDMI_FRL,

I'd maybe suggest keeping PHY_MODE_HDMI and having two submodes: one for 
TMDS (default), one for FRL.

>   };
>   
>   enum phy_media {
> 


-- 
With best wishes
Dmitry