linux-kernel - Re: [PATCH v9 0/5] staging: vc04_services: vchiq: Register devices with a custom bus

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Message-ID: <43b2929d-f6be-d382-2802-412b0928dad0@ideasonboard.com>
Date:   Thu, 20 Jul 2023 17:38:26 +0530
From:   Umang Jain <umang.jain@...asonboard.com>
To:     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
Cc:     gregkh@...uxfoundation.org, f.fainelli@...il.com,
        athierry@...hat.com, error27@...il.com,
        dave.stevenson@...pberrypi.com, kieran.bingham@...asonboard.com,
        laurent.pinchart@...asonboard.com
Subject: Re: [PATCH v9 0/5] staging: vc04_services: vchiq: Register devices
 with a custom bus_type

Hi Stefan ,


On 7/19/23 11:05 PM, Stefan Wahren wrote:
> Hi Umang,
>
> Am 19.07.23 um 18:54 schrieb Umang Jain:
>> Hi,
>>
>> One comment,
>>
>> On 7/19/23 10:14 PM, Umang Jain wrote:
>>> The patch series added a new bus type vchiq_bus_type and registers
>>> child devices in order to move them away from using platform
>>> device/driver.
>>>
>>> Patch 1/5 and 2/5 adds a new bus_type and registers them to vchiq
>>> interface
>>>
>>> Patch 3/5 and 4/5 moves the bcm2835-camera and bcm2835-audio
>>> to the new bus respectively
>>>
>>> Patch 5/5 removes a platform registeration helper which is no
>>> longer required.
>>>
>>> Changes in v9:
>>> - Fix module autoloading
>>
>> While the autoloading of bcm2835-audio, bcm2835-camera is fixed as 
>> part of this series, there is one WARN coming in when bcm2835-audio 
>> is loaded regarding dma_alloc_attr
>>
>> dmesg output: https://paste.debian.net/plain/1286359
>
> is it possible that after your patch series no DMA mask like 
> DMA_BIT_MASK(32) is provided?

I am trying to set DMA_BIT_MASK(32) via  dma_set_mask_and_coherent() but 
it fails with -EIO
>
>>
>> I am investigating further...
>>> - Implement bus_type's probe() callback to load drivers
>>> - Implement bus_type's uevent() to make sure appropriate drivers are
>>>    loaded when device are registed from vchiq.
>>>
>>> Changes in v8:
>>> - Drop dual licensing. Instead use GPL-2.0 only for patch 1/5
>>>
>>> Changes in v7:
>>> (5 out of 6 patches from v6 merged)
>>> - Split the main patch (6/6) as requested.
>>> - Use struct vchiq_device * instead of struct device * in
>>>    all bus functions.
>>> - Drop additional name attribute displayed in sysfs (redundant info)
>>> - Document vchiq_interface doesn't enumerate device discovery
>>> - remove EXPORT_SYMBOL_GPL(vchiq_bus_type)
>>>
>>> Changes in v6:
>>> - Split struct device and struct driver wrappers in vchiq_device.[ch]
>>> - Move vchiq_bus_type definition to vchiq_device.[ch] as well
>>> - return error on bus_register() failure
>>> - drop dma_set_mask_and_coherent
>>> - trivial variable name change
>>>
>>> Changes in v5:
>>> - Fixup missing "staging: " in commits' subject line
>>> - No code changes from v4
>>>
>>> Changes in v4:
>>> - Introduce patches to drop include directives from Makefile
>>>
>>> Changes in v3:
>>> - Rework entirely to replace platform devices/driver model
>>>
>>> -v2:
>>> https://lore.kernel.org/all/20221222191500.515795-1-umang.jain@ideasonboard.com/ 
>>>
>>>
>>> -v1:
>>> https://lore.kernel.org/all/20221220084404.19280-1-umang.jain@ideasonboard.com/ 
>>>
>>>
>>> Umang Jain (5):
>>>    staging: vc04_services: vchiq_arm: Add new bus type and device type
>>>    staging: vc04_services: vchiq_arm: Register vchiq_bus_type
>>>    staging: bcm2835-camera: Register bcm2835-camera with vchiq_bus_type
>>>    staging: bcm2835-audio: Register bcm2835-audio with vchiq_bus_type
>>>    staging: vc04_services: vchiq_arm: Remove vchiq_register_child()
>>>
>>>   drivers/staging/vc04_services/Makefile        |   1 +
>>>   .../vc04_services/bcm2835-audio/bcm2835.c     |  20 ++--
>>>   .../bcm2835-camera/bcm2835-camera.c           |  17 +--
>>>   .../interface/vchiq_arm/vchiq_arm.c           |  48 ++++-----
>>>   .../interface/vchiq_arm/vchiq_device.c        | 102 
>>> ++++++++++++++++++
>>>   .../interface/vchiq_arm/vchiq_device.h        |  54 ++++++++++
>>>   6 files changed, 196 insertions(+), 46 deletions(-)
>>>   create mode 100644 
>>> drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
>>>   create mode 100644 
>>> drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.h
>>>
>>