linux-kernel - Re: [PATCH] drivers: phy: cadence: cdns-dphy: Enabling lower resolutions in dphy

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Message-ID: <1ebb82ea-4b6c-4496-b7c0-17d4168d8ddf@ti.com>
Date: Wed, 6 Aug 2025 09:43:48 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: Harikrishna Shenoy <h-shenoy@...com>, <vkoul@...nel.org>,
        <kishon@...nel.org>, <u.kleine-koenig@...libre.com>,
        <linux-phy@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <devarsht@...com>, <s-jain1@...com>, <u-kumar1@...com>
Subject: Re: [PATCH] drivers: phy: cadence: cdns-dphy: Enabling lower
 resolutions in dphy

Thanks Hari for this patch

On 8/1/2025 5:23 PM, Harikrishna Shenoy wrote:
> The patch enables cdns dphy for hs_clk_rate in range between

No need of 'The patch' word

> 80 Mbps to 160 Mbps as mentioned in TRM [0] by setting the
> pll_opdiv field to 16.This change enables lower resolutions
> like 640x480 at 60Hz.

If you like to reword commit message, please feel free to use below

Enable support for hs_clk_rate between 80-160 Mbps cdns dphy
as mentioned in TRM [0] .....
With update in commit message, Please use
Reviewed-by: Udit Kumar <u-kumar1@...com>
> [0]: https://www.ti.com/lit/zip/spruil1
> (Table 12-552. DPHY_TX_PLL_CTRL Register Field Descriptions)
>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@...com>
> ---
> Test log: https://gist.github.com/h-shenoy/3975156baf403a0ff8dbcce5b49b2b89
>
>   drivers/phy/cadence/cdns-dphy.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
> index ed87a3970f83..9abed2ece9b0 100644
> --- a/drivers/phy/cadence/cdns-dphy.c
> +++ b/drivers/phy/cadence/cdns-dphy.c
> @@ -139,7 +139,7 @@ static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
>   
>   	dlane_bps = opts->hs_clk_rate;
>   
> -	if (dlane_bps > 2500000000UL || dlane_bps < 160000000UL)
> +	if (dlane_bps > 2500000000UL || dlane_bps < 80000000UL)
>   		return -EINVAL;
>   	else if (dlane_bps >= 1250000000)
>   		cfg->pll_opdiv = 1;
> @@ -149,6 +149,8 @@ static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
>   		cfg->pll_opdiv = 4;
>   	else if (dlane_bps >= 160000000)
>   		cfg->pll_opdiv = 8;
> +	else if (dlane_bps >= 80000000)
> +		cfg->pll_opdiv = 16;
>   
>   	cfg->pll_fbdiv = DIV_ROUND_UP_ULL(dlane_bps * 2 * cfg->pll_opdiv *
>   					  cfg->pll_ipdiv,