Re: [PATCH 3/4] arm64: dts: rockchip: Add HDMI1 PHY PLL clock source to VOP2 on RK3588

From: "Heiko Stübner" <heiko@sntech.de>
To: Jianfeng Liu <liujianfeng1994@gmail.com>,
	Sebastian Reichel <sebastian.reichel@collabora.com>
Cc: airlied@gmail.com, andy.yan@rock-chips.com, conor+dt@kernel.org,
	cristian.ciocaltea@collabora.com, devicetree@vger.kernel.org,
	dri-devel@lists.freedesktop.org, hjc@rock-chips.com,
	kernel@collabora.com, krzk+dt@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	robh@kernel.org, simona@ffwll.ch, tzimmermann@suse.de
Subject: Re: [PATCH 3/4] arm64: dts: rockchip: Add HDMI1 PHY PLL clock source to VOP2 on RK3588
Date: Tue, 18 Feb 2025 15:53:06 +0100	[thread overview]
Message-ID: <2425191.NG923GbCHz@diego> (raw)
In-Reply-To: <lnuceofdwm6lgibworaghcujp6rrncvn4e2xc2vzltimjw3rqu@jur7x5cxt5ue>

Am Dienstag, 18. Februar 2025, 15:13:07 MEZ schrieb Sebastian Reichel:
> Hi,
> 
> On Tue, Feb 18, 2025 at 08:17:46PM +0800, Jianfeng Liu wrote:
> > On Tue, 18 Feb 2025 11:00:57 +0100, Heiko Stübnerwrote:
> > >So I guess step1, check what error is actually returned.
> > 
> > I have checked that the return value is -517:
> > 
> > rockchip-drm display-subsystem: [drm] *ERROR* failed to get pll_hdmiphy1 with -517
> > 
> > >Step2 check if clk_get_optional need to be adapted or alternatively
> > >catch the error in the vop2 and set the clock to NULL ourself in that case.
> > 
> > I tried the following patch to set the clock to NULL when clk_get_optional
> > failed with value -517, and hdmi0 is working now. There are also some
> > boards like rock 5 itx which only use hdmi1, I think we should also add
> > this logic to vop2->pll_hdmiphy0.
> > 
> > @@ -3733,6 +3751,15 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
> >  		return PTR_ERR(vop2->pll_hdmiphy0);
> >  	}
> >  
> > +	vop2->pll_hdmiphy1 = devm_clk_get_optional(vop2->dev, "pll_hdmiphy1");
> > +	if (IS_ERR(vop2->pll_hdmiphy1)) {
> > +		drm_err(vop2->drm, "failed to get pll_hdmiphy1 with %d\n", vop2->pll_hdmiphy1);
> > +		if (vop2->pll_hdmiphy1 == -EPROBE_DEFER)
> > +			vop2->pll_hdmiphy1 = NULL;
> > +		else
> > +			return PTR_ERR(vop2->pll_hdmiphy1);
> > +	}
> > +
> 
> This first of all shows, that we should replace drm_err in this
> place with dev_err_probe(), which hides -EPROBE_DEFER errors by
> default and instead captures the reason for /sys/kernel/debug/devices_deferred.
> 
> Second what you are doing in the above suggestion will break kernel
> configurations where VOP is built-in and the HDMI PHY is build as a
> module.
> 
> But I also think it would be better to have the clocks defined in the
> SoC level DT. I suppose that means vop2_bind would have to check if
> the HDMI controller <ID> is enabled and only requests pll_hdmiphy<ID>
> based on that. Considering there is the OF graph pointing from VOP
> to the enabled HDMI controllers, it should be able to do that.


I was more thinking about fixing the correct thing, with something like:

----------- 8< ----------

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index cf7720b9172f..50faafbf5dda 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -5258,6 +5258,10 @@ of_clk_get_hw_from_clkspec(struct of_phandle_args *clkspec)
        if (!clkspec)
                return ERR_PTR(-EINVAL);

+       /* Check if node in clkspec is in disabled/fail state */
+       if (!of_device_is_available(clkspec->np))
+               return ERR_PTR(-ENOENT);
+
        mutex_lock(&of_clk_mutex);
        list_for_each_entry(provider, &of_clk_providers, link) {
                if (provider->node == clkspec->np) {
----------- 8< ----------

Because right now the clk framework does not handle nodes in
failed/disabled state and would defer indefinitly.




