linux-kernel - Re: [PATCH] drm/bridge/synopsys: dsi: Allow VPG to be enabled via debugfs

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Date:   Thu, 25 Apr 2019 12:42:48 +0000
From:   Matt Redfearn <matt.redfearn@...nci.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:     Archit Taneja <architt@...eaurora.org>,
        David Airlie <airlied@...ux.ie>,
        Philippe Cornu <philippe.cornu@...com>,
        Matthew Redfearn <matthew.redfearn@...nci.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Nickey Yang <nickey.yang@...k-chips.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] drm/bridge/synopsys: dsi: Allow VPG to be enabled via
 debugfs

Hi Laurent,

Thanks for the review!


On 25/04/2019 10:31, Laurent Pinchart wrote:
> On Wed, Apr 24, 2019 at 02:22:18PM +0000, Matt Redfearn wrote:
>> The Synopsys MIPI DSI IP contains a video test pattern generator which
>> is helpful in debugging video timing with connected displays.
>> Add a debugfs directory containing files which allow the VPG to be
>> enabled and disabled, and it's orientation to be changed.
> 
> s/it's/its/
>>
>> Signed-off-by: Matt Redfearn <matt.redfearn@...nci.com>
>>
>> ---
>>
>>   drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 55 +++++++++++++++++++
>>   1 file changed, 55 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> index 0ee440216b8..a1ee2306382 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> @@ -10,6 +10,7 @@
>>   
>>   #include <linux/clk.h>
>>   #include <linux/component.h>
>> +#include <linux/debugfs.h>
>>   #include <linux/iopoll.h>
>>   #include <linux/module.h>
>>   #include <linux/of_device.h>
>> @@ -86,6 +87,8 @@
>>   #define VID_MODE_TYPE_NON_BURST_SYNC_EVENTS	0x1
>>   #define VID_MODE_TYPE_BURST			0x2
>>   #define VID_MODE_TYPE_MASK			0x3
>> +#define VID_MODE_VPG_ENABLE		BIT(16)
>> +#define VID_MODE_VPG_HORIZONTAL		BIT(24)
>>   
>>   #define DSI_VID_PKT_SIZE		0x3c
>>   #define VID_PKT_SIZE(p)			((p) & 0x3fff)
>> @@ -234,6 +237,15 @@ struct dw_mipi_dsi {
>>   	u32 format;
>>   	unsigned long mode_flags;
>>   
>> +#ifdef CONFIG_DEBUG_FS
>> +	struct dentry *debugfs_root;
>> +	struct dentry *debugfs_vpg;
>> +	struct dentry *debugfs_vpg_horizontal;
>> +
>> +	bool vpg;
>> +	bool vpg_horizontal;
>> +#endif /* CONFIG_DEBUG_FS */
>> +
>>   	struct dw_mipi_dsi *master; /* dual-dsi master ptr */
>>   	struct dw_mipi_dsi *slave; /* dual-dsi slave ptr */
>>   
>> @@ -525,6 +537,11 @@ static void dw_mipi_dsi_video_mode_config(struct dw_mipi_dsi *dsi)
>>   	else
>>   		val |= VID_MODE_TYPE_NON_BURST_SYNC_EVENTS;
>>   
>> +	if (dsi->vpg) {
> 
> Won't this break if CONFIG_DDEBUG_FS is not defined ?

Ah yes - quite right.

> 
>> +		val |= VID_MODE_VPG_ENABLE;
>> +		val |= dsi->vpg_horizontal ? VID_MODE_VPG_HORIZONTAL : 0;
>> +	}
>> +
>>   	dsi_write(dsi, DSI_VID_MODE_CFG, val);
>>   }
>>   
>> @@ -935,6 +952,41 @@ static const struct drm_bridge_funcs dw_mipi_dsi_bridge_funcs = {
>>   	.attach	      = dw_mipi_dsi_bridge_attach,
>>   };
>>   
>> +#ifdef CONFIG_DEBUG_FS
>> +
>> +static void dw_mipi_dsi_debugfs_init(struct dw_mipi_dsi *dsi)
>> +{
>> +	struct dentry *d;
>> +
>> +	d = debugfs_create_dir(dev_name(dsi->dev), NULL);
>> +	if (IS_ERR(d)) {
>> +		dev_err(dsi->dev, "failed to create debugfs root\n");
>> +		return;
>> +	}
>> +	dsi->debugfs_root = d;
>> +
>> +	d = debugfs_create_bool("vpg", 0660, dsi->debugfs_root, &dsi->vpg);
>> +	dsi->debugfs_vpg = d;
> 
> If you don't handle failures here you don't need the intermediate d
> variable, you can just assign dsi->debugfs_vpg directly.

True - I will update it.

> 
>> +
>> +	d = debugfs_create_bool("vpg_horizontal", 0660, dsi->debugfs_root,
>> +				&dsi->vpg_horizontal);
>> +	dsi->debugfs_vpg_horizontal = d;
> 
> Same here.


And here - thanks!

Matt

> 
>> +}
>> +
>> +static void dw_mipi_dsi_debugfs_remove(struct dw_mipi_dsi *dsi)
>> +{
>> +	debugfs_remove(dsi->debugfs_vpg_horizontal);
>> +	debugfs_remove(dsi->debugfs_vpg);
>> +	debugfs_remove(dsi->debugfs_root);
>> +}
>> +
>> +#else
>> +
>> +static void dw_mipi_dsi_debugfs_init(struct dw_mipi_dsi *dsi) { }
>> +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)
>> @@ -1005,6 +1057,7 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>   		clk_disable_unprepare(dsi->pclk);
>>   	}
>>   
>> +	dw_mipi_dsi_debugfs_init(dsi);
>>   	pm_runtime_enable(dev);
>>   
>>   	dsi->dsi_host.ops = &dw_mipi_dsi_host_ops;
>> @@ -1012,6 +1065,7 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
>>   	ret = mipi_dsi_host_register(&dsi->dsi_host);
>>   	if (ret) {
>>   		dev_err(dev, "Failed to register MIPI host: %d\n", ret);
>> +		dw_mipi_dsi_debugfs_remove(dsi);
>>   		return ERR_PTR(ret);
>>   	}
>>   
>> @@ -1029,6 +1083,7 @@ static void __dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi)
>>   	mipi_dsi_host_unregister(&dsi->dsi_host);
>>   
>>   	pm_runtime_disable(dsi->dev);
>> +	dw_mipi_dsi_debugfs_remove(dsi);
>>   }
>>   
>>   void dw_mipi_dsi_set_slave(struct dw_mipi_dsi *dsi, struct dw_mipi_dsi *slave)
>