Re: [PATCH v3 1/3] Kconfig : Remove HAS_IOMEM dependency for Graphics support

From: Thomas Huth <thuth@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>
Cc: Farhan Ali <alifm@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
	linux-fbdev@vger.kernel.org, geert@linux-m68k.org,
	tomi.valkeinen@ti.com, b.zolnierkie@samsung.com
Subject: Re: [PATCH v3 1/3] Kconfig : Remove HAS_IOMEM dependency for Graphics support
Date: Wed, 21 Feb 2018 12:29:19 +0100	[thread overview]
Message-ID: <5dfa9213-0e63-54d0-8700-1ced4efd4c28@redhat.com> (raw)
In-Reply-To: <1f8907d4-c4a3-d41b-8834-679dcc85de4a@de.ibm.com>

On 21.02.2018 12:22, Christian Borntraeger wrote:
> 
> 
> On 02/21/2018 12:14 PM, Thomas Huth wrote:
>> On 21.02.2018 12:09, Christian Borntraeger wrote:
>>>
>>>
>>> On 02/21/2018 11:32 AM, Cornelia Huck wrote:
>>>> On Wed, 21 Feb 2018 11:22:38 +0100
>>>> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
>>>>
>>>>> On 02/21/2018 11:05 AM, Christian Borntraeger wrote:
>>>>>>
>>>>>>
>>>>>> On 02/19/2018 05:38 PM, Farhan Ali wrote:  
>>>>>>>
>>>>>>>
>>>>>>> On 02/19/2018 11:25 AM, Thomas Huth wrote:  
>>>>>>>> On 19.02.2018 16:47, Farhan Ali wrote:  
>>>>>>>>> The 'commit e25df1205f37 ("[S390] Kconfig: menus with depends on HAS_IOMEM.")'
>>>>>>>>> added the HAS_IOMEM dependecy for "Graphics support". This disabled the
>>>>>>>>> "Graphics support" menu for S390. But if we enable VT layer for S390,
>>>>>>>>> we would also need to enable the dummy console. So let's remove the
>>>>>>>>> HAS_IOMEM dependency.
>>>>>>>>>
>>>>>>>>> Move this dependency to sub menu items and console drivers that use
>>>>>>>>> io memory.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Farhan Ali <alifm@linux.vnet.ibm.com>
>>>>>>>>> ---
>>>>>>>>>   drivers/video/Kconfig         | 21 +++++++++++----------
>>>>>>>>>   drivers/video/console/Kconfig |  4 ++--
>>>>>>>>>   2 files changed, 13 insertions(+), 12 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>>>>>>>>> index 3c20af9..8f10915 100644
>>>>>>>>> --- a/drivers/video/Kconfig
>>>>>>>>> +++ b/drivers/video/Kconfig
>>>>>>>>> @@ -3,7 +3,6 @@
>>>>>>>>>   #
>>>>>>>>>     menu "Graphics support"
>>>>>>>>> -    depends on HAS_IOMEM
>>>>>>>>>     config HAVE_FB_ATMEL
>>>>>>>>>       bool
>>>>>>>>> @@ -11,20 +10,22 @@ config HAVE_FB_ATMEL
>>>>>>>>>   config SH_LCD_MIPI_DSI
>>>>>>>>>       bool
>>>>>>>>>   -source "drivers/char/agp/Kconfig"
>>>>>>>>> +if HAS_IOMEM
>>>>>>>>> +    source "drivers/char/agp/Kconfig"
>>>>>>>>>   -source "drivers/gpu/vga/Kconfig"
>>>>>>>>> +    source "drivers/gpu/vga/Kconfig"
>>>>>>>>>   -source "drivers/gpu/host1x/Kconfig"
>>>>>>>>> -source "drivers/gpu/ipu-v3/Kconfig"
>>>>>>>>> +    source "drivers/gpu/host1x/Kconfig"
>>>>>>>>> +    source "drivers/gpu/ipu-v3/Kconfig"
>>>>>>>>>   -source "drivers/gpu/drm/Kconfig"
>>>>>>>>> +    source "drivers/gpu/drm/Kconfig"  
>>>>>>
>>>>>>
>>>>>> Hmmm, looks like that this makes it impossible to select VIRTIO_GPU - need still more
>>>>>> work.
>>>>>>   
>>>>> Sorry my fault. I had CONFIG_PCI disabled.
>>>>
>>>> That smells like the s390 HAS_IOMEM stuff needs more work -- I guess
>>>> that you want to enable a ccw virtio-gpu device, not a pci one, right?
>>>
>>> It is a ccw virtio-gpu. But s390 has no IOMEM without CONFIG_PCI, so you cannot
>>> select VIRTIO_GPU, which needs DRM, which need IOMEM.
>>
>> So the 'source "drivers/gpu/drm/Kconfig"' should maybe rather reside
>> outside of the "if HAS_IOMEM" path? Or does it not compile anymore that way?
> 
> virtio-gpu depends on drm. So in essence it boils down to if you want virtio-gpu
> you also need to enable PCI, even if the actual channel is ccw.

But if you need to enable PCI to get IOMEM, I wonder why this patch here
is needed at all? The Graphics menu / VT dummy console should be
available in the config if IOMEM is enabled anyway?

 Thomas