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Date:   Fri, 18 Aug 2023 14:39:08 +0900
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Subject: Re: [PATCH v2 6/6] drm/vkms: Add a module param to enable/disable the
 default device
Content-Language: en-US
To:     Maira Canal <mairacanal@riseup.net>,
        Jim Shargo <jshargo@chromium.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@gmail.com>,
        Haneen Mohammed <hamohammed.sa@gmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Melissa Wen <melissa.srw@gmail.com>,
        Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
        Thomas Zimmermann <tzimmermann@suse.de>
Cc:     dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230623222353.97283-1-jshargo@chromium.org>
 <20230623222353.97283-7-jshargo@chromium.org>
 <64c40359-d0ee-5070-2a52-033c7e655e0a@riseup.net>
From:   Brandon Ross Pollack <brpol@chromium.org>
In-Reply-To: <64c40359-d0ee-5070-2a52-033c7e655e0a@riseup.net>
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On 6/26/23 03:04, Maira Canal wrote:
> Hi Jim,
>
> On 6/23/23 19:23, Jim Shargo wrote:
>> In many testing circumstances, we will want to just create a new device
>> and test against that. If we create a default device, it can be annoying
>> to have to manually select the new device instead of choosing the only
>> one that exists.
>>
>> The param, enable_default, is defaulted to true to maintain backwards
>> compatibility.
>>
>> Signed-off-by: Jim Shargo <jshargo@chromium.org>
>> ---
>>   drivers/gpu/drm/vkms/vkms_drv.c | 44 ++++++++++++++++++++++-----------
>>   1 file changed, 29 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c 
>> b/drivers/gpu/drm/vkms/vkms_drv.c
>> index 314a04659c5f..1cb56c090a65 100644
>> --- a/drivers/gpu/drm/vkms/vkms_drv.c
>> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
>> @@ -42,17 +42,26 @@
>>   #define DRIVER_MAJOR    1
>>   #define DRIVER_MINOR    0
>>   +static bool enable_default_device = true;
>> +module_param_named(enable_default_device, enable_default_device, 
>> bool, 0444);
>> +MODULE_PARM_DESC(enable_default_device,
>> +         "Enable/Disable creating the default device");
>
> Wouldn't be better to just call it "enable_default"?

At the risk of being annoyingly pedantic, I actually like the original 
name better because it makes it clear it is an entire device and setup,

including the planes/encoders/connectors/crtcs needed and connecting 
them as necessary etc.  I just feel "device" here makes it clearer what 
is the default thing.

>
> Also, could you add this parameter to vkms_config debugfs file?

But of course! This is the last comment before I send out the new series.


Thank you so much for your time, looking forward to the next round of 
comments.


>
> Best Regards,
> - Maíra
>
>> +
>>   static bool enable_cursor = true;
>>   module_param_named(enable_cursor, enable_cursor, bool, 0444);
>> -MODULE_PARM_DESC(enable_cursor, "Enable/Disable cursor support");
>> +MODULE_PARM_DESC(enable_cursor,
>> +         "Enable/Disable cursor support for the default device");
>>     static bool enable_writeback = true;
>>   module_param_named(enable_writeback, enable_writeback, bool, 0444);
>> -MODULE_PARM_DESC(enable_writeback, "Enable/Disable writeback 
>> connector support");
>> +MODULE_PARM_DESC(
>> +    enable_writeback,
>> +    "Enable/Disable writeback connector support for the default 
>> device");
>>     static bool enable_overlay;
>>   module_param_named(enable_overlay, enable_overlay, bool, 0444);
>> -MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");
>> +MODULE_PARM_DESC(enable_overlay,
>> +         "Enable/Disable overlay support for the default device");
>>     DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
>>   @@ -278,10 +287,7 @@ void vkms_remove_device(struct vkms_device 
>> *vkms_device)
>>   static int __init vkms_init(void)
>>   {
>>       int ret;
>> -    struct platform_device *pdev;
>> -    struct vkms_device_setup vkms_device_setup = {
>> -        .configfs = NULL,
>> -    };
>> +    struct platform_device *default_pdev = NULL;
>>         ret = platform_driver_register(&vkms_platform_driver);
>>       if (ret) {
>> @@ -289,19 +295,27 @@ static int __init vkms_init(void)
>>           return ret;
>>       }
>>   -    pdev = platform_device_register_data(NULL, DRIVER_NAME, 0,
>> -                         &vkms_device_setup,
>> -                         sizeof(vkms_device_setup));
>> -    if (IS_ERR(pdev)) {
>> -        DRM_ERROR("Unable to register default vkms device\n");
>> -        platform_driver_unregister(&vkms_platform_driver);
>> -        return PTR_ERR(pdev);
>> +    if (enable_default_device) {
>> +        struct vkms_device_setup vkms_device_setup = {
>> +            .configfs = NULL,
>> +        };
>> +
>> +        default_pdev = platform_device_register_data(
>> +            NULL, DRIVER_NAME, 0, &vkms_device_setup,
>> +            sizeof(vkms_device_setup));
>> +        if (IS_ERR(default_pdev)) {
>> +            DRM_ERROR("Unable to register default vkms device\n");
>> + platform_driver_unregister(&vkms_platform_driver);
>> +            return PTR_ERR(default_pdev);
>> +        }
>>       }
>>         ret = vkms_init_configfs();
>>       if (ret) {
>>           DRM_ERROR("Unable to initialize configfs\n");
>> -        platform_device_unregister(pdev);
>> +        if (default_pdev)
>> +            platform_device_unregister(default_pdev);
>> +
>>           platform_driver_unregister(&vkms_platform_driver);
>>       }
>
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> Date: Sun, 25 Jun 2023 15:04:05 -0300
> MIME-Version: 1.0
> Subject: Re: [PATCH v2 6/6] drm/vkms: Add a module param to 
> enable/disable the
> default device
> Content-Language: en-US
> To: Jim Shargo <jshargo@chromium.org>, Daniel Vetter <daniel@ffwll.ch>,
> David Airlie <airlied@gmail.com>, Haneen Mohammed 
> <hamohammed.sa@gmail.com>,
> Jonathan Corbet <corbet@lwn.net>,
> Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
> Maxime Ripard <mripard@kernel.org>, Melissa Wen <melissa.srw@gmail.com>,
> Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
> Thomas Zimmermann <tzimmermann@suse.de>
> References: <20230623222353.97283-1-jshargo@chromium.org>
> <20230623222353.97283-7-jshargo@chromium.org>
> From: Maira Canal <mairacanal@riseup.net>
> In-Reply-To: <20230623222353.97283-7-jshargo@chromium.org>
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>
> Hi Jim,
>
> On 6/23/23 19:23, Jim Shargo wrote:
>> In many testing circumstances, we will want to just create a new device
>> and test against that. If we create a default device, it can be annoying
>> to have to manually select the new device instead of choosing the only
>> one that exists.
>>
>> The param, enable_default, is defaulted to true to maintain backwards
>> compatibility.
>>
>> Signed-off-by: Jim Shargo <jshargo@chromium.org>
>> ---
>>   drivers/gpu/drm/vkms/vkms_drv.c | 44 ++++++++++++++++++++++-----------
>>   1 file changed, 29 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c 
>> b/drivers/gpu/drm/vkms/vkms_drv.c
>> index 314a04659c5f..1cb56c090a65 100644
>> --- a/drivers/gpu/drm/vkms/vkms_drv.c
>> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
>> @@ -42,17 +42,26 @@
>>   #define DRIVER_MAJOR    1
>>   #define DRIVER_MINOR    0
>>   +static bool enable_default_device = true;
>> +module_param_named(enable_default_device, enable_default_device, 
>> bool, 0444);
>> +MODULE_PARM_DESC(enable_default_device,
>> +         "Enable/Disable creating the default device");
>
> Wouldn't be better to just call it "enable_default"?
>
> Also, could you add this parameter to vkms_config debugfs file?
>
> Best Regards,
> - Maíra
>
>> +
>>   static bool enable_cursor = true;
>>   module_param_named(enable_cursor, enable_cursor, bool, 0444);
>> -MODULE_PARM_DESC(enable_cursor, "Enable/Disable cursor support");
>> +MODULE_PARM_DESC(enable_cursor,
>> +         "Enable/Disable cursor support for the default device");
>>     static bool enable_writeback = true;
>>   module_param_named(enable_writeback, enable_writeback, bool, 0444);
>> -MODULE_PARM_DESC(enable_writeback, "Enable/Disable writeback 
>> connector support");
>> +MODULE_PARM_DESC(
>> +    enable_writeback,
>> +    "Enable/Disable writeback connector support for the default 
>> device");
>>     static bool enable_overlay;
>>   module_param_named(enable_overlay, enable_overlay, bool, 0444);
>> -MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");
>> +MODULE_PARM_DESC(enable_overlay,
>> +         "Enable/Disable overlay support for the default device");
>>     DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
>>   @@ -278,10 +287,7 @@ void vkms_remove_device(struct vkms_device 
>> *vkms_device)
>>   static int __init vkms_init(void)
>>   {
>>       int ret;
>> -    struct platform_device *pdev;
>> -    struct vkms_device_setup vkms_device_setup = {
>> -        .configfs = NULL,
>> -    };
>> +    struct platform_device *default_pdev = NULL;
>>         ret = platform_driver_register(&vkms_platform_driver);
>>       if (ret) {
>> @@ -289,19 +295,27 @@ static int __init vkms_init(void)
>>           return ret;
>>       }
>>   -    pdev = platform_device_register_data(NULL, DRIVER_NAME, 0,
>> -                         &vkms_device_setup,
>> -                         sizeof(vkms_device_setup));
>> -    if (IS_ERR(pdev)) {
>> -        DRM_ERROR("Unable to register default vkms device\n");
>> -        platform_driver_unregister(&vkms_platform_driver);
>> -        return PTR_ERR(pdev);
>> +    if (enable_default_device) {
>> +        struct vkms_device_setup vkms_device_setup = {
>> +            .configfs = NULL,
>> +        };
>> +
>> +        default_pdev = platform_device_register_data(
>> +            NULL, DRIVER_NAME, 0, &vkms_device_setup,
>> +            sizeof(vkms_device_setup));
>> +        if (IS_ERR(default_pdev)) {
>> +            DRM_ERROR("Unable to register default vkms device\n");
>> + platform_driver_unregister(&vkms_platform_driver);
>> +            return PTR_ERR(default_pdev);
>> +        }
>>       }
>>         ret = vkms_init_configfs();
>>       if (ret) {
>>           DRM_ERROR("Unable to initialize configfs\n");
>> -        platform_device_unregister(pdev);
>> +        if (default_pdev)
>> +            platform_device_unregister(default_pdev);
>> +
>>           platform_driver_unregister(&vkms_platform_driver);
>>       }
>