linux-kernel - Re: [PATCH v12 5/6] staging: bcm2835-camera: Register bcm2835-camera with vchiq_bus

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Message-ID: <ca3ec33e-4e42-9bce-eb24-99df0e39473e@ideasonboard.com>
Date:   Mon, 9 Oct 2023 09:50:29 +0530
From:   Umang Jain <umang.jain@...asonboard.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-staging@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org,
        linux-rpi-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Stefan Wahren <stefan.wahren@...e.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Adrien Thierry <athierry@...hat.com>,
        Dan Carpenter <error27@...il.com>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Kieran Bingham <kieran.bingham@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH v12 5/6] staging: bcm2835-camera: Register bcm2835-camera
 with vchiq_bus_type

Hi Greg,

Sorry for late reply, as I was traveling and then was on vacation for 
rest of the week.

On 10/5/23 1:34 PM, Greg Kroah-Hartman wrote:
> On Sat, Sep 23, 2023 at 08:01:59PM +0530, Umang Jain wrote:
>> Register the bcm2835-camera with the vchiq_bus_type instead of using
>> platform driver/device.
>>
>> Since we moved away bcm2835-camera from platform driver/device,
>> we have to set the DMA mask explicitly. Set the DMA mask at probe
>> time.
>>
>> Also the VCHIQ firmware doesn't support device enumeration, hence
>> one has to maintain a list of devices to be registered in the interface.
>>
>> Signed-off-by: Umang Jain <umang.jain@...asonboard.com>
>> ---
>>   .../bcm2835-camera/bcm2835-camera.c           | 21 ++++++++++---------
>>   .../interface/vchiq_arm/vchiq_arm.c           | 11 +++++++---
>>   2 files changed, 19 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
>> index fcad5118f3e8..c873eace1437 100644
>> --- a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
>> +++ b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
>> @@ -11,6 +11,7 @@
>>    *          Luke Diamand @ Broadcom
>>    */
>>   
>> +#include <linux/dma-mapping.h>
>>   #include <linux/errno.h>
>>   #include <linux/kernel.h>
>>   #include <linux/module.h>
>> @@ -24,8 +25,8 @@
>>   #include <media/v4l2-event.h>
>>   #include <media/v4l2-common.h>
>>   #include <linux/delay.h>
>> -#include <linux/platform_device.h>
>>   
>> +#include "../interface/vchiq_arm/vchiq_bus.h"
>>   #include "../vchiq-mmal/mmal-common.h"
>>   #include "../vchiq-mmal/mmal-encodings.h"
>>   #include "../vchiq-mmal/mmal-vchiq.h"
>> @@ -1841,7 +1842,7 @@ static struct v4l2_format default_v4l2_format = {
>>   	.fmt.pix.sizeimage = 1024 * 768,
>>   };
>>   
>> -static int bcm2835_mmal_probe(struct platform_device *pdev)
>> +static int bcm2835_mmal_probe(struct vchiq_device *device)
>>   {
>>   	int ret;
>>   	struct bcm2835_mmal_dev *dev;
>> @@ -1852,9 +1853,9 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
>>   	unsigned int resolutions[MAX_BCM2835_CAMERAS][2];
>>   	int i;
>>   
>> -	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
>> +	ret = dma_set_mask_and_coherent(&device->dev, DMA_BIT_MASK(32));
>>   	if (ret) {
>> -		dev_err(&pdev->dev, "dma_set_mask_and_coherent failed: %d\n", ret);
>> +		dev_err(&device->dev, "dma_set_mask_and_coherent failed: %d\n", ret);
>>   		return ret;
>>   	}
>>   
>> @@ -1902,7 +1903,7 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
>>   						       &camera_instance);
>>   		ret = v4l2_device_register(NULL, &dev->v4l2_dev);
>>   		if (ret) {
>> -			dev_err(&pdev->dev, "%s: could not register V4L2 device: %d\n",
>> +			dev_err(&device->dev, "%s: could not register V4L2 device: %d\n",
>>   				__func__, ret);
>>   			goto free_dev;
>>   		}
>> @@ -1982,7 +1983,7 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
>>   	return ret;
>>   }
>>   
>> -static void bcm2835_mmal_remove(struct platform_device *pdev)
>> +static void bcm2835_mmal_remove(struct vchiq_device *device)
>>   {
>>   	int camera;
>>   	struct vchiq_mmal_instance *instance = gdev[0]->instance;
>> @@ -1994,17 +1995,17 @@ static void bcm2835_mmal_remove(struct platform_device *pdev)
>>   	vchiq_mmal_finalise(instance);
>>   }
>>   
>> -static struct platform_driver bcm2835_camera_driver = {
>> +static struct vchiq_driver bcm2835_camera_driver = {
>>   	.probe		= bcm2835_mmal_probe,
>> -	.remove_new	= bcm2835_mmal_remove,
>> +	.remove		= bcm2835_mmal_remove,
>>   	.driver		= {
>>   		.name	= "bcm2835-camera",
>>   	},
>>   };
>>   
>> -module_platform_driver(bcm2835_camera_driver)
>> +module_vchiq_driver(bcm2835_camera_driver)
>>   
>>   MODULE_DESCRIPTION("Broadcom 2835 MMAL video capture");
>>   MODULE_AUTHOR("Vincent Sanders");
>>   MODULE_LICENSE("GPL");
>> -MODULE_ALIAS("platform:bcm2835-camera");
>> +MODULE_ALIAS("bcm2835-camera");
> Now that you are on your own bus, why do you need the MODULE_ALIAS()
> line at all?

Because it breaks the module auto-loading support...

If you look at the vchiq_bus patch (3/6) in this series, there is 
vchiq_bus_uevent() which sends a event that includes the MODALIAS.
>
> thanks,
>
> greg k-h