[Buildroot] [PATCH v2] configs/olimex_a20_olinuxino: fix mali not working because Linux version >= 4.20

[Giulio Benetti]

Hi Thomas,

> Il giorno 18 ott 2021, alle ore 21:45, Thomas Petazzoni <thomas.petazzoni at bootlin.com> ha scritto:
> 
> On Fri, 15 Oct 2021 10:15:14 +0200
> Giulio Benetti <giulio.benetti at benettiengineering.com> wrote:
> 
>> Since on olinuxino_lime/lime2 we have a Linux version >= 4.20 we need to
>> pass drm_kms_helper.drm_leak_fbdev_smem=1 to kernel command-line that
>> really enables DRM_FBDEV_LEAK_PHYS_SMEM. CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM
>> only adds the code for this, but drm_leak_fbdev_smem is 0 by default, so we
>> need to override it with 1. Same goes for drm_fbdev_overalloc that
>> must be at least 200 for having a double buffer that is required by
>> Mali. This fixes both olimex_a20_olinuxino_lime and lime2 that use
>> extlinux.conf.
>> 
>> Signed-off-by: Giulio Benetti <giulio.benetti at benettiengineering.com>
> 
> I appreciate the idea, but I'm not sure if we want this. Indeed, the
> A20 Olinuxino defconfigs are meant to be minimal, and there's nothing
> that forces anyone to use the proprietary Mali driver+blob, they can
> also use mesa3d instead, which might have different requirements.

They instead enable specifically sunxi-mali-mainline* in lime and lime2 defconfigs.
So at the moment sunxi-mali-mainline is built but it can’t work and it doesn’t make sense.
Also up to Linux 4.20 this neither worked because of lack of double buffer. So basically here sunxi-mali-mainline I’m pretty sure never worked.

Lime and Lime2 both use this extlinux.conf and they are the only ones.

The other way is to remove sunxi-mali-mainline from Lime and Lime2 that is a possible idea.
Let me know what you prefer.

Kind regards
Giulio Benetti

> 
> So I'm rather keen on enabling your patch on
> sunxi-mali-mainline-driver/Config.in, but not this one I'm afraid.
> 
> Of course, if others disagree, I can change my mind :)
> 
> Thanks!
> 
> Thomas
> -- 
> Thomas Petazzoni, co-owner and CEO, Bootlin
> Embedded Linux and Kernel engineering and training
> https://bootlin.com
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