Re: [PATCH v4 03/11] drm/bridge: cdns-dsi: Fix Phy _init() and _exit()

[Tomi Valkeinen]

Hi,

On 22/06/2024 14:09, Aradhya Bhatia wrote:
> Initialize the Phy during the cdns-dsi _resume(), and de-initialize it
> during the _suspend().
>
> Also power-off the Phy from bridge_disable.
>
> Fixes: fced5a364dee ("drm/bridge: cdns: Convert to phy framework")
> Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
> ---
>   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);
>   	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;
>   }
>   

So with this patch, phy_init/exit will be called in the resume/suspend 
functions. That looks fine.

But the phy_power_on/phy_power_off looks odd to me. Here you add 
phy_power_off() to cdns_dsi_bridge_disable(), which sounds fine. But 
phy_power_on() is called in cdns_dsi_hs_init(), and that is called in 
cdns_dsi_bridge_enable() (which sounds fine), but also in 
cdns_dsi_bridge_pre_enable().

So doesn't that mean cdns_dsi_hs_init() call in cdns_dsi_bridge_enable() 
is extra, as it effectively does nothing (it exists right away if 
dsi->phy_initialized == true)?

 Tomi