linux-kernel - Re: [RFC,3/3] drm/komeda: Allow non-component drm

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Date:   Thu, 17 Oct 2019 08:20:56 +0000
From:   Brian Starkey <Brian.Starkey@....com>
To:     "james qian wang (Arm Technology China)" <james.qian.wang@....com>
CC:     Mihail Atanassov <Mihail.Atanassov@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Liviu Dudau <Liviu.Dudau@....com>,
        Russell King <linux@...linux.org.uk>,
        Maxime Ripard <mripard@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        nd <nd@....com>, Sean Paul <sean@...rly.run>
Subject: Re: [RFC,3/3] drm/komeda: Allow non-component drm_bridge only
 endpoints

On Thu, Oct 17, 2019 at 03:07:59AM +0000, james qian wang (Arm Technology China) wrote:
> On Wed, Oct 16, 2019 at 04:22:07PM +0000, Brian Starkey wrote:
> > 
> > If James is strongly against merging this, maybe we just swap
> > wholesale to bridge? But for me, the pragmatic approach would be this
> > stop-gap.
> >
> 
> This is a good idea, and I vote +ULONG_MAX :)
> 
> and I also checked tda998x driver, it supports bridge. so swap the
> wholesale to brige is perfect. :)
> 

Well, as Mihail wrote, it's definitely not perfect.

Today, if you rmmod tda998x with the DPU driver still loaded,
everything will be unbound gracefully.

If we swap to bridge, then rmmod'ing tda998x (or any other bridge
driver the DPU is using) with the DPU driver still loaded will result
in a crash.

So, there really are proper benefits to sticking with the component
code for tda998x, which is why I'd like to understand why you're so
against this patch?

Thanks,
-Brian