linux-kernel - Re: [PATCH] drm: rockchip: Don't require MIPI DSI device when it's used for ISP

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Message-ID: <7044f324-5a45-4a4c-a15e-86614e53acf0@rock-chips.com>
Date: Mon, 19 Feb 2024 11:02:01 +0800
From: Andy Yan <andy.yan@...k-chips.com>
To: Ondřej Jirman <megi@....cz>,
 linux-kernel@...r.kernel.org, Sandy Huang <hjc@...k-chips.com>,
 Heiko Stübner <heiko@...ech.de>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 "open list:DRM DRIVERS FOR ROCKCHIP" <dri-devel@...ts.freedesktop.org>,
 "moderated list:ARM/Rockchip SoC support"
 <linux-arm-kernel@...ts.infradead.org>,
 "open list:ARM/Rockchip SoC support" <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH] drm: rockchip: Don't require MIPI DSI device when it's
 used for ISP

Hi Ondrej:

On 2/18/24 23:17, Ondřej Jirman wrote:
> Hi Andy,
> 
> On Sun, Feb 18, 2024 at 07:14:56PM +0800, Andy Yan wrote:
>> Hi,
>>
>> On 2/18/24 02:39, Ondřej Jirman wrote:
>>> From: Ondrej Jirman <megi@....cz>
>>>
>>> On RK3399 one MIPI DSI device can be alternatively used with the ISP1,
>>> to provide RX DPHY. When this is the case (ISP1 is enabled in device
>>> tree), probe success of DRM is tied to probe success of ISP1 connected
>>> camera sensor. This can fail if the user is able to killswitch the camera
>>> power, like on Pinephone Pro.
>>>
>>> Detect use of MIPI DSI controller by ISP, and don't include it in
>>> component match list in that case.
>>>
>>
>> Isn't this supposed to be taken care of within the dts?
>> Since DPHY1 should exclusively used by MIPI DSI1 and ISP1, then if
>> a device want to use ISP1, the DSI1 should be disabled in dts.
> 
> DSI1 can't be disabled, because it provides PHY device for ISP1 in this
> scenario.
> 
> The problem is that in this scenario DRM keeps waiting for DSI1 device,
> despite it just being used for PHY for ISP1 and not as a component for
> rockchip DRM driver.


Oh, get it.
With a quick look, seems that Heiko has already take this scenario into consideration
when add PHY function in the dsi drivers[0]
Does this mean the current drivers does not work as expected?

[0]https://patchwork.freedesktop.org/patch/420386/
> 
> See:
> 
>          isp1: isp1@...20000 {
>                  compatible = "rockchip,rk3399-cif-isp";
>                  reg = <0x0 0xff920000 0x0 0x4000>;
>                  interrupts = <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH 0>;
>                  clocks = <&cru SCLK_ISP1>,
>                           <&cru ACLK_ISP1_WRAPPER>,
>                           <&cru HCLK_ISP1_WRAPPER>;
>                  clock-names = "isp", "aclk", "hclk";
>                  iommus = <&isp1_mmu>;
>                  phys = <&mipi_dsi1>;  <---------
>                  phy-names = "dphy";
>                  power-domains = <&power RK3399_PD_ISP1>;
>                  status = "disabled";
> 
> If mipi_dsi1 is disabled, isp1 will never probe.
> 
> It's a consequence of this special dual use of mipi_dsi1.
> 
> kind regards,
> 	o.
> 
>>> Signed-off-by: Ondrej Jirman <megi@....cz>
>>> ---
>>>    drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 47 +++++++++++++++++++++
>>>    1 file changed, 47 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>>> index ab55d7132550..f47de94ad576 100644
>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>>> @@ -354,6 +354,43 @@ static void rockchip_drm_match_remove(struct device *dev)
>>>    		device_link_del(link);
>>>    }
>>> +/*
>>> + * Check if ISP block linked to a mipi-dsi device via phys phandle is
>>> + * enabled in device tree.
>>> + */
>>> +static bool rockchip_drm_is_mipi1_and_used_by_isp(struct device *dev)
>>> +{
>>> +	struct device_node *np = NULL, *phy_np;
>>> +
>>> +	if (!of_device_is_compatible(dev->of_node, "rockchip,rk3399-mipi-dsi"))
>>> +		return false;
>>> +
>>> +	while (true) {
>>> +		np = of_find_compatible_node(np, NULL, "rockchip,rk3399-cif-isp");
>>> +		if (!np)
>>> +			break;
>>> +
>>> +		if (!of_device_is_available(np)) {
>>> +			of_node_put(np);
>>> +			continue;
>>> +		}
>>> +
>>> +		phy_np = of_parse_phandle(np, "phys", 0);
>>> +		if (!phy_np) {
>>> +			of_node_put(np);
>>> +			continue;
>>> +		}
>>> +
>>> +		of_node_put(phy_np);
>>> +		of_node_put(np);
>>> +
>>> +		if (phy_np == dev->of_node)
>>> +			return true;
>>> +	}
>>> +
>>> +	return false;
>>> +}
>>> +
>>>    static struct component_match *rockchip_drm_match_add(struct device *dev)
>>>    {
>>>    	struct component_match *match = NULL;
>>> @@ -371,6 +408,16 @@ static struct component_match *rockchip_drm_match_add(struct device *dev)
>>>    			if (!d)
>>>    				break;
>>> +			/*
>>> +			 * If mipi1 is connected to ISP, we don't want to wait for mipi1 component,
>>> +			 * because it will not be used by DRM anyway, to not tie success of camera
>>> +			 * driver probe to display pipeline initialization.
>>> +			 */
>>> +			if (rockchip_drm_is_mipi1_and_used_by_isp(d)) {
>>> +				dev_info(d, "used by ISP1, skipping from DRM\n");
>>> +				continue;
>>> +			}
>>> +
>>>    			device_link_add(dev, d, DL_FLAG_STATELESS);
>>>    			component_match_add(dev, &match, component_compare_dev, d);
>>>    		} while (true);