linux-kernel - Re: [PATCH v5 03/13] drm/bridge: cdns-dsi: Fix Phy _init() and

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Message-ID: <i5o65ui4psc7b4hsqq5hl7t2hvf43xc7pmvlrcstjhqp2okwx3@izezpdd7tmk2>
Date: Sun, 20 Oct 2024 14:34:30 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
Cc: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Dominik Haller <d.haller@...tec.de>, Sam Ravnborg <sam@...nborg.org>, 
	Kieran Bingham <kieran.bingham+renesas@...asonboard.com>, Nishanth Menon <nm@...com>, 
	Vignesh Raghavendra <vigneshr@...com>, Devarsh Thakkar <devarsht@...com>, 
	Praneeth Bajjuri <praneeth@...com>, Udit Kumar <u-kumar1@...com>, 
	Jayesh Choudhary <j-choudhary@...com>, DRI Development List <dri-devel@...ts.freedesktop.org>, 
	Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 03/13] drm/bridge: cdns-dsi: Fix Phy _init() and
 _exit()

On Sun, Oct 20, 2024 at 01:24:01AM +0530, Aradhya Bhatia wrote:
> From: Aradhya Bhatia <a-bhatia1@...com>
> 
> Initialize the Phy during the cdns-dsi _resume(), and de-initialize it
> during the _suspend().
> 
> Also power-off the Phy from bridge_disable.

Please describe why, not what. Especially, if it is considered a fix.

> 
> Fixes: fced5a364dee ("drm/bridge: cdns: Convert to phy framework")
> Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
> Signed-off-by: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
> ---
>  drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> index 5159c3f0853e..d89c32bae2b9 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> @@ -672,6 +672,10 @@ static void cdns_dsi_bridge_disable(struct drm_bridge *bridge)
>  	if (dsi->platform_ops && dsi->platform_ops->disable)
>  		dsi->platform_ops->disable(dsi);
>  
> +	phy_power_off(dsi->dphy);
> +	dsi->link_initialized = false;
> +	dsi->phy_initialized = false;
> +
>  	pm_runtime_put(dsi->base.dev);
>  }
>  
> @@ -698,7 +702,6 @@ static void cdns_dsi_hs_init(struct cdns_dsi *dsi)
>  	       DPHY_CMN_PDN | DPHY_PLL_PDN,
>  	       dsi->regs + MCTL_DPHY_CFG0);
>  
> -	phy_init(dsi->dphy);

This moves the call order, moving phy_init() before
platform_ops->enable(). It should be documented with the clear pointer
that it considered to be safe.

>  	phy_set_mode(dsi->dphy, PHY_MODE_MIPI_DPHY);
>  	phy_configure(dsi->dphy, &output->phy_opts);
>  	phy_power_on(dsi->dphy);
> @@ -1120,6 +1123,8 @@ static int __maybe_unused cdns_dsi_resume(struct device *dev)
>  	clk_prepare_enable(dsi->dsi_p_clk);
>  	clk_prepare_enable(dsi->dsi_sys_clk);
>  
> +	phy_init(dsi->dphy);
> +
>  	return 0;
>  }
>  
> @@ -1127,10 +1132,11 @@ static int __maybe_unused cdns_dsi_suspend(struct device *dev)
>  {
>  	struct cdns_dsi *dsi = dev_get_drvdata(dev);
>  
> +	phy_exit(dsi->dphy);
> +
>  	clk_disable_unprepare(dsi->dsi_sys_clk);
>  	clk_disable_unprepare(dsi->dsi_p_clk);
>  	reset_control_assert(dsi->dsi_p_rst);
> -	dsi->link_initialized = false;
>  	return 0;
>  }
>  
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry