[PATCH] drm: mediatek: remove IOMMU_DMA select

[PATCH] drm: mediatek: remove IOMMU_DMA select

[Arnd Bergmann]

We get a harmless build warning when trying to use the mediatek
DRM driver with IOMMU support disabled:

warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT)

However, the IOMMU_DMA symbol is not meant to be used by drivers
at all, and this driver doesn't seem to have a strict dependency
on it other than using the mediatek IOMMU driver that does.

Since we also want to be able to do compile tests with the
driver on other platforms, the IOMMU_DMA symbol should not
be selected here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
If someone has a better explanation about why the 'select' is here,
let me know, it certainly seems out of place.

 drivers/gpu/drm/mediatek/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig
index 0c06a69d7f04..545973f6b743 100644
--- a/drivers/gpu/drm/mediatek/Kconfig
+++ b/drivers/gpu/drm/mediatek/Kconfig
@@ -7,7 +7,6 @@ config DRM_MEDIATEK
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL
-	select IOMMU_DMA
 	select MEMORY
 	select MTK_SMI
 	help
-- 
2.7.0

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Re: [PATCH] drm: mediatek: remove IOMMU_DMA select

[Arnd Bergmann]

On Wednesday 11 May 2016 22:11:07 Arnd Bergmann wrote:
> We get a harmless build warning when trying to use the mediatek
> DRM driver with IOMMU support disabled:
> 
> warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT)
> 
> However, the IOMMU_DMA symbol is not meant to be used by drivers
> at all, and this driver doesn't seem to have a strict dependency
> on it other than using the mediatek IOMMU driver that does.
> 
> Since we also want to be able to do compile tests with the
> driver on other platforms, the IOMMU_DMA symbol should not
> be selected here.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> If someone has a better explanation about why the 'select' is here,
> let me know, it certainly seems out of place.

Sorry, I didn't mean to send this as a reply to "More build fixes for
omapdrm in current -next", I copied the wrong command line.

I'll resend it if necessary.

	Arnd

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Re: [PATCH] drm: mediatek: remove IOMMU_DMA select

[Robin Murphy]

On 11/05/16 21:11, Arnd Bergmann wrote:
> We get a harmless build warning when trying to use the mediatek
> DRM driver with IOMMU support disabled:
>
> warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT)
>
> However, the IOMMU_DMA symbol is not meant to be used by drivers
> at all, and this driver doesn't seem to have a strict dependency
> on it other than using the mediatek IOMMU driver that does.
>
> Since we also want to be able to do compile tests with the
> driver on other platforms, the IOMMU_DMA symbol should not
> be selected here.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> If someone has a better explanation about why the 'select' is here,
> let me know, it certainly seems out of place.

Ack - it's neither an IOMMU driver nor a DMA API implementation, so it 
has no business with IOMMU_DMA. If there's an IOMMU dependency in 
general it should be on MTK_IOMMU, not underlying implementation details.

Robin.

>   drivers/gpu/drm/mediatek/Kconfig | 1 -
>   1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig
> index 0c06a69d7f04..545973f6b743 100644
> --- a/drivers/gpu/drm/mediatek/Kconfig
> +++ b/drivers/gpu/drm/mediatek/Kconfig
> @@ -7,7 +7,6 @@ config DRM_MEDIATEK
>   	select DRM_KMS_HELPER
>   	select DRM_MIPI_DSI
>   	select DRM_PANEL
> -	select IOMMU_DMA
>   	select MEMORY
>   	select MTK_SMI
>   	help
>

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Re: [PATCH] drm: mediatek: remove IOMMU_DMA select

[Philipp Zabel]

Am Mittwoch, den 11.05.2016, 22:11 +0200 schrieb Arnd Bergmann:
> We get a harmless build warning when trying to use the mediatek
> DRM driver with IOMMU support disabled:
> 
> warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT)
> 
> However, the IOMMU_DMA symbol is not meant to be used by drivers
> at all, and this driver doesn't seem to have a strict dependency
> on it other than using the mediatek IOMMU driver that does.
> 
> Since we also want to be able to do compile tests with the
> driver on other platforms, the IOMMU_DMA symbol should not
> be selected here.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> If someone has a better explanation about why the 'select' is here,
> let me know, it certainly seems out of place.

No, it just has been there since the initial RFC and nobody noticed.

>  drivers/gpu/drm/mediatek/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig
> index 0c06a69d7f04..545973f6b743 100644
> --- a/drivers/gpu/drm/mediatek/Kconfig
> +++ b/drivers/gpu/drm/mediatek/Kconfig
> @@ -7,7 +7,6 @@ config DRM_MEDIATEK
>  	select DRM_KMS_HELPER
>  	select DRM_MIPI_DSI
>  	select DRM_PANEL
> -	select IOMMU_DMA
>  	select MEMORY
>  	select MTK_SMI
>  	help

Acked-by: Philipp Zabel <p.zabel@pengutronix.de>

I tried
  make ARCH=arm64 allnoconfig
and then set
  CONFIG_MODULES=y
  CONFIG_ARCH_MEDIATEK=y
  CONFIG_DRM=m
  CONFIG_DRM_MEDIATEK=m

And it builds fine with IOMMU_DMA/MTK_IOMMU disabled.

thanks
Philipp

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Re: [PATCH] drm: mediatek: remove IOMMU_DMA select

[Thierry Reding]

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On Wed, May 11, 2016 at 10:15:20PM +0200, Arnd Bergmann wrote:
> On Wednesday 11 May 2016 22:11:07 Arnd Bergmann wrote:
> > We get a harmless build warning when trying to use the mediatek
> > DRM driver with IOMMU support disabled:
> > 
> > warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT)
> > 
> > However, the IOMMU_DMA symbol is not meant to be used by drivers
> > at all, and this driver doesn't seem to have a strict dependency
> > on it other than using the mediatek IOMMU driver that does.
> > 
> > Since we also want to be able to do compile tests with the
> > driver on other platforms, the IOMMU_DMA symbol should not
> > be selected here.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > If someone has a better explanation about why the 'select' is here,
> > let me know, it certainly seems out of place.
> 
> Sorry, I didn't mean to send this as a reply to "More build fixes for
> omapdrm in current -next", I copied the wrong command line.
> 
> I'll resend it if necessary.

That's probably the reason why patchwork didn't include the commit
message in the downloaded mbox. I've pieced it together manually and
applied this to topic/drm-misc.

Thanks,
Thierry

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