linux-kernel - Re: [PATCH v6 0/6] staging: vc04_services: vchiq: Register devices with a custom bus

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Message-ID: <Y85MOdAVh/fv5HRt@pendragon.ideasonboard.com>
Date:   Mon, 23 Jan 2023 10:58:33 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Umang Jain <umang.jain@...asonboard.com>
Cc:     Stefan Wahren <stefan.wahren@...e.com>,
        linux-staging@...ts.linux.dev,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        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>,
        Paul Elder <paul.elder@...asonboard.com>
Subject: Re: [PATCH v6 0/6] staging: vc04_services: vchiq: Register devices
 with a custom bus_type

On Mon, Jan 23, 2023 at 01:18:30PM +0530, Umang Jain wrote:
> Hi Stefan,
> 
> Thank for the testing.
> 
> On 1/23/23 5:04 AM, Stefan Wahren wrote:
> > Hi Umang,
> >
> > Am 20.01.23 um 21:10 schrieb Umang Jain:
> >> This series just introduces five extra patches for dropping include
> >> directives from Makefiles (suggested by Greg KH) and rebased.
> >>
> >> The main patch (6/6) removes platform device/driver abuse and moves
> >> things to standard device/driver model using a custom_bus. Specific
> >> details are elaborated in the commit message.
> >>
> >> The patch series is based on top of d514392f17fd (tag: next-20230120)
> >> of linux-next.
> >
> > applied this series on top of linux-next and build it with 
> > arm/multi_v7_defconfig plus the following:
> >
> > CONFIG_BCM_VIDEOCORE=y
> > CONFIG_BCM2835_VCHIQ=m
> > CONFIG_VCHIQ_CDEV=y
> > CONFIG_SND_BCM2835=m
> > CONFIG_VIDEO_BCM2835=m
> > CONFIG_BCM2835_VCHIQ_MMAL=m
> >
> > and the devices doesn't register on Raspberry Pi 3 B Plus:
> >
> > [   25.523337] vchiq: module is from the staging directory, the quality is unknown, you have been warned.
> > [   25.541647] bcm2835_vchiq 3f00b840.mailbox: Failed to register bcm2835_audio vchiq device
> > [   25.553692] bcm2835_vchiq 3f00b840.mailbox: Failed to register bcm2835-camera vchiq device
> 
> I was able to reproduce and it seems the issue here is the change 
> mentioned in the cover
> 
> - drop dma_set_mask_and_coherent
> 
> in V6.
> 
> (I usually test patches on RPi 4B with vcsm-cma and bcm2835-isp applied 
> so my branch has the DMA hunk included while I was testing V6)
> 
> Below is the hunk which should resolve the issue.
> 
> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> @@ -6,6 +6,7 @@
>    */
> 
>   #include <linux/device/bus.h>
> +#include <linux/dma-mapping.h>
>   #include <linux/slab.h>
>   #include <linux/string.h>
> 
> @@ -72,6 +73,12 @@ int vchiq_device_register(struct device *parent, 
> const char *name)
>          device->dev.type = &vchiq_device_type;
>          device->dev.release = vchiq_device_release;
> 
> +       ret = dma_set_mask_and_coherent(&device->dev, DMA_BIT_MASK(32));
> +       if (ret < 0) {
> +               vchiq_device_release(&device->dev);
> +               return ret;
> +       }
> +
>          ret = device_register(&device->dev);
>          if (ret) {
>                  put_device(&device->dev);
> 
> It seems we need to include the dma_set_mask_and_coherent() even if 
> bcm2835-audio, bcm2835-camera device doesn't do DMA? I need to look into 
> why is that/
> 
>   Laurent, any thoughts on this please?

Nothing that immediately springs to my mind. Can you investigate ?

-- 
Regards,

Laurent Pinchart