Message-ID: <562a7ab4-2bd0-44e1-92b3-a16bb642ab11@linaro.org>
Date: Mon, 15 Jan 2024 13:52:27 +0100
From: neil.armstrong@...aro.org
To: Heiko Stübner <heiko@...ech.de>,
 Farouk Bouabid <farouk.bouabid@...obroma-systems.com>, victor.liu@....com,
 andrzej.hajda@...el.com, rfoss@...nel.org, jonas@...boo.se,
 jernej.skrabec@...il.com, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
 shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
 festevam@...il.com, linux-imx@....com, khilman@...libre.com,
 jbrunet@...libre.com, martin.blumenstingl@...glemail.com,
 hjc@...k-chips.com, yannick.fertre@...s.st.com,
 raphael.gallais-pou@...s.st.com, philippe.cornu@...s.st.com,
 mcoquelin.stm32@...il.com, alexandre.torgue@...s.st.com,
 dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-amlogic@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-stm32@...md-mailman.stormreply.com
Cc: quentin.schulz@...obroma-systems.com, bouabid.farouk97@...il.com
Subject: Re: [PATCH] drm/bridge: synopsys: dw-mipi-dsi: fix deferred dsi host
 probe breaks dsi device probe

On 15/01/2024 11:07, Heiko Stübner wrote:
> Am Montag, 15. Januar 2024, 09:45:10 CET schrieb neil.armstrong@...aro.org:
>> Hi,
>>
>> On 12/01/2024 19:07, Farouk Bouabid wrote:
>>> dw-mipi-dsi based drivers such as dw-mipi-dsi-rockchip or dw_mipi_dsi-stm
>>> depend on dw_mipi_dsi_probe() to initialize the dw_mipi_dsi driver
>>> structure (dmd pointer). This structure is only initialized once
>>> dw_mipi_dsi_probe() returns, creating the link between the locally created
>>> structure and the actual dmd pointer.
>>>
>>> Probing the dsi host can be deferred in case of dependency to a dsi
>>> phy-supply (eg. "rockchip,px30-dsi-dphy"). Meanwhile dsi-device drivers
>>> like panels (eg. "ltk050h3146w") can already be registered on the bus.
>>> In that case, when attempting, to register the dsi host from
>>> dw_mipi_dsi_probe() using mipi_dsi_host_register(), the panel probe is
>>> called with a dsi-host pointer that is still locally allocated in
>>> dw_mipi_dsi_probe().
>>>
>>> While probing, the panel driver tries to attach to a dsi host
>>> (mipi_dsi_attach()) which calls in return for the specific dsi host
>>> attach hook. (e.g. dw_mipi_dsi_rockchip_host_attach()).
>>> dw_mipi_dsi_rockchip uses the component framework.
>>> In the attach hook, the host component is registered which calls in return
>>> for drm_bridge_attach() while trying to bind the component
>>> (dw_mipi_dsi_bind())
>>
>> In meson_dw_mipi_dsi I simply fixed this by getting rid of components...
> 
> If I remember correctly, the component element is there on Rockchip to
> facilitate running dual-dsi displays (1 panel driven by 2 dsi controllers),
> because it allows to wait for both controllers to have probed individually
> before trying to drive the display.
> 
> Not sure if there is a better way to do that now.

Device links should limit probe deferal to a minimum, at least it works fine
on the systems I work on

Neil

> 
> 
> Heiko
> 
> 
>>> drm_bridge_attach() requires a valid drm bridge parameter. However, the
>>> drm bridge (&dmd->bridge) that will be passed, is not yet initialized since
>>> the dw_mipi_dsi_probe() has not yet returned. This call will fail with a
>>> fatal error (invalid bridge) causing the panel to not be probed again.
>>>
>>> To simplify the issue: drm_bridge_attach() depends on the result pointer
>>> of dw_mipi_dsi_probe().
>>> While, if the dsi probe is deferred, drm_bridge_attach() is called before
>>> dw_mipi_dsi_probe() returns.
>>>
>>> drm_bridge_attach+0x14/0x1ac
>>> dw_mipi_dsi_bind+0x24/0x30
>>> dw_mipi_dsi_rockchip_bind+0x258/0x378
>>> component_bind_all+0x118/0x248
>>> rockchip_drm_bind+0xb0/0x1f8
>>> try_to_bring_up_aggregate_device+0x168/0x1d4
>>> __component_add+0xa4/0x170
>>> component_add+0x14/0x20
>>> dw_mipi_dsi_rockchip_host_attach+0x54/0x144
>>> dw_mipi_dsi_host_attach+0x9c/0xcc
>>> mipi_dsi_attach+0x28/0x3c
>>> ltk050h3146w_probe+0x10c/0x1a4
>>> mipi_dsi_drv_probe+0x20/0x2c
>>> really_probe+0x148/0x2ac
>>> __driver_probe_device+0x78/0x12c
>>> driver_probe_device+0xdc/0x160
>>> __device_attach_driver+0xb8/0x134
>>> bus_for_each_drv+0x80/0xdc
>>> __device_attach+0xa8/0x1b0
>>> device_initial_probe+0x14/0x20
>>> bus_probe_device+0xa8/0xac
>>> device_add+0x5cc/0x778
>>> mipi_dsi_device_register_full+0xd8/0x198
>>> mipi_dsi_host_register+0x98/0x18c
>>> __dw_mipi_dsi_probe+0x290/0x35c
>>> dw_mipi_dsi_probe+0x10/0x6c
>>> dw_mipi_dsi_rockchip_probe+0x208/0x3e4
>>> platform_probe+0x68/0xdc
>>> really_probe+0x148/0x2ac
>>> __driver_probe_device+0x78/0x12c
>>> driver_probe_device+0xdc/0x160
>>> __device_attach_driver+0xb8/0x134
>>> bus_for_each_drv+0x80/0xdc
>>> __device_attach+0xa8/0x1b0
>>> device_initial_probe+0x14/0x20
>>> bus_probe_device+0xa8/0xac
>>> deferred_probe_work_func+0x88/0xc0
>>> process_one_work+0x138/0x260
>>> worker_thread+0x32c/0x438
>>> kthread+0x118/0x11c
>>> ret_from_fork+0x10/0x20
>>> ---[ end trace 0000000000000000 ]---
>>>
>>> Fix this by initializing directly the dmd pointer in dw_mipi_dsi_probe(),
>>> which requires also initializting the dmd->bridge attributes that are
>>> required in drm_bridge_attach() before calling mipi_dsi_host_register().
>>>
>>> Signed-off-by: Farouk Bouabid <farouk.bouabid@...obroma-systems.com>
>>> ---
>>>    drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c   |  4 +-
>>>    drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 42 ++++++++++---------
>>>    drivers/gpu/drm/meson/meson_dw_mipi_dsi.c     |  8 ++--
>>>    .../gpu/drm/rockchip/dw-mipi-dsi-rockchip.c   |  5 +--
>>>    drivers/gpu/drm/stm/dw_mipi_dsi-stm.c         |  5 +--
>>>    include/drm/bridge/dw_mipi_dsi.h              |  5 ++-
>>>    6 files changed, 35 insertions(+), 34 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c b/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
>>> index 3ff30ce80c5b..469976ad3b19 100644
>>> --- a/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
>>> +++ b/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
>>> @@ -881,8 +881,8 @@ static int imx93_dsi_probe(struct platform_device *pdev)
>>>    	dsi->pdata.priv_data = dsi;
>>>    	platform_set_drvdata(pdev, dsi);
>>>    
>>> -	dsi->dmd = dw_mipi_dsi_probe(pdev, &dsi->pdata);
>>> -	if (IS_ERR(dsi->dmd))
>>> +	ret = dw_mipi_dsi_probe(pdev, &dsi->pdata, &dsi->dmd);
>>> +	if (ret < 0)
>>>    		return dev_err_probe(dev, PTR_ERR(dsi->dmd),
>>>    				     "failed to probe dw_mipi_dsi\n");
>>>    
>>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>>> index 824fb3c65742..306cba366ba8 100644
>>> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>>> @@ -1184,18 +1184,19 @@ static void dw_mipi_dsi_debugfs_remove(struct dw_mipi_dsi *dsi) { }
>>>    
>>>    #endif /* CONFIG_DEBUG_FS */
>>>    
>>> -static struct dw_mipi_dsi *
>>> -__dw_mipi_dsi_probe(struct platform_device *pdev,
>>> -		    const struct dw_mipi_dsi_plat_data *plat_data)
>>> +int __dw_mipi_dsi_probe(struct platform_device *pdev,
>>> +		    const struct dw_mipi_dsi_plat_data *plat_data, struct dw_mipi_dsi **dsi_p)
>>>    {
>>>    	struct device *dev = &pdev->dev;
>>>    	struct reset_control *apb_rst;
>>>    	struct dw_mipi_dsi *dsi;
>>>    	int ret;
>>>    
>>> -	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
>>> -	if (!dsi)
>>> -		return ERR_PTR(-ENOMEM);
>>> +	*dsi_p = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
>>> +	if (!*dsi_p)
>>> +		return -ENOMEM;
>>> +
>>> +	dsi = *dsi_p;
>>>    
>>>    	dsi->dev = dev;
>>>    	dsi->plat_data = plat_data;
>>> @@ -1203,13 +1204,13 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>>    	if (!plat_data->phy_ops->init || !plat_data->phy_ops->get_lane_mbps ||
>>>    	    !plat_data->phy_ops->get_timing) {
>>>    		DRM_ERROR("Phy not properly configured\n");
>>> -		return ERR_PTR(-ENODEV);
>>> +		return -ENODEV;
>>>    	}
>>>    
>>>    	if (!plat_data->base) {
>>>    		dsi->base = devm_platform_ioremap_resource(pdev, 0);
>>>    		if (IS_ERR(dsi->base))
>>> -			return ERR_PTR(-ENODEV);
>>> +			return -ENODEV;
>>>    
>>>    	} else {
>>>    		dsi->base = plat_data->base;
>>> @@ -1219,7 +1220,7 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>>    	if (IS_ERR(dsi->pclk)) {
>>>    		ret = PTR_ERR(dsi->pclk);
>>>    		dev_err(dev, "Unable to get pclk: %d\n", ret);
>>> -		return ERR_PTR(ret);
>>> +		return ret;
>>>    	}
>>>    
>>>    	/*
>>> @@ -1233,14 +1234,14 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>>    		if (ret != -EPROBE_DEFER)
>>>    			dev_err(dev, "Unable to get reset control: %d\n", ret);
>>>    
>>> -		return ERR_PTR(ret);
>>> +		return ret;
>>>    	}
>>>    
>>>    	if (apb_rst) {
>>>    		ret = clk_prepare_enable(dsi->pclk);
>>>    		if (ret) {
>>>    			dev_err(dev, "%s: Failed to enable pclk\n", __func__);
>>> -			return ERR_PTR(ret);
>>> +			return ret;
>>>    		}
>>>    
>>>    		reset_control_assert(apb_rst);
>>> @@ -1255,19 +1256,20 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>>    
>>>    	dsi->dsi_host.ops = &dw_mipi_dsi_host_ops;
>>>    	dsi->dsi_host.dev = dev;
>>> +	dsi->bridge.driver_private = dsi;
>>> +	dsi->bridge.funcs = &dw_mipi_dsi_bridge_funcs;
>>> +	dsi->bridge.of_node = pdev->dev.of_node;
>>> +
>>>    	ret = mipi_dsi_host_register(&dsi->dsi_host);
>>>    	if (ret) {
>>>    		dev_err(dev, "Failed to register MIPI host: %d\n", ret);
>>>    		pm_runtime_disable(dev);
>>>    		dw_mipi_dsi_debugfs_remove(dsi);
>>> -		return ERR_PTR(ret);
>>> +		return ret;
>>>    	}
>>>    
>>> -	dsi->bridge.driver_private = dsi;
>>> -	dsi->bridge.funcs = &dw_mipi_dsi_bridge_funcs;
>>> -	dsi->bridge.of_node = pdev->dev.of_node;
>>>    
>>> -	return dsi;
>>> +	return 0;
>>>    }
>>>    
>>>    static void __dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi)
>>> @@ -1301,11 +1303,11 @@ EXPORT_SYMBOL_GPL(dw_mipi_dsi_get_bridge);
>>>    /*
>>>     * Probe/remove API, used from platforms based on the DRM bridge API.
>>>     */
>>> -struct dw_mipi_dsi *
>>> -dw_mipi_dsi_probe(struct platform_device *pdev,
>>> -		  const struct dw_mipi_dsi_plat_data *plat_data)
>>> +int dw_mipi_dsi_probe(struct platform_device *pdev,
>>> +		  const struct dw_mipi_dsi_plat_data *plat_data,
>>> +		  struct dw_mipi_dsi **dsi_p)
>>>    {
>>> -	return __dw_mipi_dsi_probe(pdev, plat_data);
>>> +	return __dw_mipi_dsi_probe(pdev, plat_data, dsi_p);
>>>    }
>>>    EXPORT_SYMBOL_GPL(dw_mipi_dsi_probe);
>>>    
>>> diff --git a/drivers/gpu/drm/meson/meson_dw_mipi_dsi.c b/drivers/gpu/drm/meson/meson_dw_mipi_dsi.c
>>> index e5fe4e994f43..b103f3e31f2a 100644
>>> --- a/drivers/gpu/drm/meson/meson_dw_mipi_dsi.c
>>> +++ b/drivers/gpu/drm/meson/meson_dw_mipi_dsi.c
>>> @@ -262,6 +262,7 @@ static int meson_dw_mipi_dsi_probe(struct platform_device *pdev)
>>>    {
>>>    	struct meson_dw_mipi_dsi *mipi_dsi;
>>>    	struct device *dev = &pdev->dev;
>>> +	int ret;
>>>    
>>>    	mipi_dsi = devm_kzalloc(dev, sizeof(*mipi_dsi), GFP_KERNEL);
>>>    	if (!mipi_dsi)
>>> @@ -315,10 +316,9 @@ static int meson_dw_mipi_dsi_probe(struct platform_device *pdev)
>>>    	mipi_dsi->pdata.priv_data = mipi_dsi;
>>>    	platform_set_drvdata(pdev, mipi_dsi);
>>>    
>>> -	mipi_dsi->dmd = dw_mipi_dsi_probe(pdev, &mipi_dsi->pdata);
>>> -	if (IS_ERR(mipi_dsi->dmd))
>>> -		return dev_err_probe(dev, PTR_ERR(mipi_dsi->dmd),
>>> -				     "Failed to probe dw_mipi_dsi\n");
>>> +	ret = dw_mipi_dsi_probe(pdev, &mipi_dsi->pdata, &mipi_dsi->dmd);
>>> +	if (ret < 0)
>>> +		return dev_err_probe(dev, ret, "Failed to probe dw_mipi_dsi\n");
>>>    
>>>    	return 0;
>>>    }
>>> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
>>> index 6396f9324dab..4df32747476c 100644
>>> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
>>> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
>>> @@ -1457,9 +1457,8 @@ static int dw_mipi_dsi_rockchip_probe(struct platform_device *pdev)
>>>    	if (IS_ERR(phy_provider))
>>>    		return PTR_ERR(phy_provider);
>>>    
>>> -	dsi->dmd = dw_mipi_dsi_probe(pdev, &dsi->pdata);
>>> -	if (IS_ERR(dsi->dmd)) {
>>> -		ret = PTR_ERR(dsi->dmd);
>>> +	ret = dw_mipi_dsi_probe(pdev, &dsi->pdata, &dsi->dmd);
>>> +	if (ret < 0) {
>>>    		if (ret != -EPROBE_DEFER)
>>>    			DRM_DEV_ERROR(dev,
>>>    				      "Failed to probe dw_mipi_dsi: %d\n", ret);
>>> diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>>> index d5f8c923d7bc..44dbbfc277d8 100644
>>> --- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>>> +++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>>> @@ -518,9 +518,8 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
>>>    
>>>    	platform_set_drvdata(pdev, dsi);
>>>    
>>> -	dsi->dsi = dw_mipi_dsi_probe(pdev, &dw_mipi_dsi_stm_plat_data);
>>> -	if (IS_ERR(dsi->dsi)) {
>>> -		ret = PTR_ERR(dsi->dsi);
>>> +	ret = dw_mipi_dsi_probe(pdev, &dw_mipi_dsi_stm_plat_data, &dsi->dsi);
>>> +	if (ret < 0) {
>>>    		dev_err_probe(dev, ret, "Failed to initialize mipi dsi host\n");
>>>    		goto err_dsi_probe;
>>>    	}
>>> diff --git a/include/drm/bridge/dw_mipi_dsi.h b/include/drm/bridge/dw_mipi_dsi.h
>>> index 65d5e68065e3..f073e819251e 100644
>>> --- a/include/drm/bridge/dw_mipi_dsi.h
>>> +++ b/include/drm/bridge/dw_mipi_dsi.h
>>> @@ -76,9 +76,10 @@ struct dw_mipi_dsi_plat_data {
>>>    	void *priv_data;
>>>    };
>>>    
>>> -struct dw_mipi_dsi *dw_mipi_dsi_probe(struct platform_device *pdev,
>>> +int dw_mipi_dsi_probe(struct platform_device *pdev,
>>>    				      const struct dw_mipi_dsi_plat_data
>>> -				      *plat_data);
>>> +				      *plat_data,
>>> +					  struct dw_mipi_dsi **dsi_p);
>>>    void dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi);
>>>    int dw_mipi_dsi_bind(struct dw_mipi_dsi *dsi, struct drm_encoder *encoder);
>>>    void dw_mipi_dsi_unbind(struct dw_mipi_dsi *dsi);
>>
>>
> 
> 
> 
> 

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