linux-kernel - Re: [PATCH] drm: aspeed: Select CMA only if available

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Message-ID: <aae72ebf-2c9c-8cc4-4598-e8bb896b9a24@tronnes.org>
Date:   Fri, 5 Apr 2019 13:18:44 +0200
From:   Noralf Trønnes <noralf@...nnes.org>
To:     Joel Stanley <joel@....id.au>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Andrew Jeffery <andrew@...id.au>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] drm: aspeed: Select CMA only if available



Den 05.04.2019 07.28, skrev Joel Stanley:
> When building this driver for architectures where CMA is not available.
> 
> Fixes: 4f2a8f5898ec ("drm: Add ASPEED GFX driver")
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Joel Stanley <joel@....id.au>
> ---
> This fixes the build break.
> 
> Another question is if we need to select this at all, as we have a
> reserved memory region to allocate from. I am not familiar with this
> area, so advice is welcome.
> 
>  drivers/gpu/drm/aspeed/Kconfig | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/aspeed/Kconfig b/drivers/gpu/drm/aspeed/Kconfig
> index 42b74d18a41b..1775fb85ec74 100644
> --- a/drivers/gpu/drm/aspeed/Kconfig
> +++ b/drivers/gpu/drm/aspeed/Kconfig
> @@ -4,8 +4,8 @@ config DRM_ASPEED_GFX
>  	select DRM_KMS_HELPER
>  	select DRM_KMS_CMA_HELPER
>  	select DRM_PANEL
> -	select DMA_CMA
> -	select CMA
> +	select DMA_CMA if HAVE_DMA_CONTIGUOUS
> +	select CMA if HAVE_DMA_CONTIGUOUS

I'm no expert on this, but the rule is that you should not select
options that are user visible which both of these are. The user should
select them. So I believe that you should remove them.

Docs: Documentation/kbuild/kconfig-language.txt

Noralf.

>  	select MFD_SYSCON
>  	help
>  	  Chose this option if you have an ASPEED AST2500 SOC Display
>