[PATCH 05/20] drm/meson: Use drm_fbdev_generic_setup()

[Maxime Ripard]

On Wed, Sep 12, 2018 at 11:48:34AM +0200, Neil Armstrong wrote:
> Hi Noralf,
> 
> On 08/09/2018 15:46, Noralf Trønnes wrote:
> > The CMA helper is already using the drm_fb_helper_generic_probe part of
> > the generic fbdev emulation. This patch makes full use of the generic
> > fbdev emulation by using its drm_client callbacks. This means that
> > drm_mode_config_funcs->output_poll_changed and drm_driver->lastclose are
> > now handled by the emulation code. Additionally fbdev unregister happens
> > automatically on drm_dev_unregister().
> > 
> > The drm_fbdev_generic_setup() call is put after drm_dev_register() in the
> > driver. This is done to highlight the fact that fbdev emulation is an
> > internal client that makes use of the driver, it is not part of the
> > driver as such. If fbdev setup fails, an error is printed, but the driver
> > succeeds probing.
> 
> I can't really ack/nack this move, on one side it's great to have a
> generic fbdev emulation instead of the old fbdev code, but on the
> other side the Amlogic platform (like allwinner, samsung, rockchip,
> ...)  still relies on an Fbdev variant of the libMali that uses
> smem_start...
> 
> I know it's dirty and fbdev based code should be legacy now, but I
> consider it like an user-space breakage...
> 
> I'll be happy if ARM provided it's Mali vendors a Fbdev libMali that
> could use FBINFO_HIDE_SMEM_START and allocate BO's from the DRM
> driver, it won't be the case and it will never be the case until the
> Lima projects finalizes.
> 
> So for me it's a no-go until Lima lands upstream in Linux *and* Mesa.

My feelings exactly. If the choice is between reducing the DRM driver
by a couple of dozens of lines or keeping the mali working, I'll pick
the latter, every single day.

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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