From: "Michel Dänzer" <michel@daenzer.net>
To: Daniel Vetter <daniel@ffwll.ch>, Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@linux.ie>,
Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [RFC][PATCH 00/11] DRM driver for fbdev devices
Date: Wed, 27 Mar 2019 10:55:25 +0100 [thread overview]
Message-ID: <6c6f22ff-b643-ee02-aacc-6c86f20fe0ea@daenzer.net> (raw)
In-Reply-To: <CAKMK7uGOhAP0EjoKwLf+HUyoNX0Li5NL6dBw4+ir9Ae704pHkA@mail.gmail.com>
On 2019-03-27 10:41 a.m., Daniel Vetter wrote:
> On Wed, Mar 27, 2019 at 10:10 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> Am 26.03.19 um 15:53 schrieb Daniel Vetter:
>>>
>>> Looks surprisingly clean, at least from a quick read. Only big thing I
>>> noticed on the implementation side is that you probably want to use the
>>> simple display helpers. At least that's a much better fit for simple
>>> display hw supported by these fbdev drivers.
>>
>> I thought about using the simple-DRM helpers, but found that a full DRM
>> driver would be more helpful for porting over fbdev drivers. Unless
>> simple DRM is a hard requirement, I'd prefer to leave it this way.
>>
>> For those devices that only support a single pipeline, the conversion to
>> simple DRM should then be mandatory during the porting process.
>
> fbdev only supports a single output, all multi-head extensions are
> driver specific ioctl hacks. Given that all you can do is switch it on
> or off (with a given mode), simple pipe helpers are the perfect fit
> for fbdev.
>
> Some drivers might support more (like multiple heads, or at least
> different outputs), and those we should convert over. But at least for
> step 1 in converting fbdev drivers over, simple pipe is the right
> starting point I think.
Converting an fbdev driver to a KMS one loses some features:
1) Dynamically switching modes / colour formats via fbdev.
2) fbcon acceleration (or maybe this can be preserved?).
In turn, it allows exposing additional functionality:
3) Multiple outputs via KMS.
Is there any benefit in converting a driver without adding 3)? If not,
is simple pipe still a good starting point?
--
Earthling Michel Dänzer | https://www.amd.com
Libre software enthusiast | Mesa and X developer
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next prev parent reply other threads:[~2019-03-27 9:55 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 9:17 [RFC][PATCH 00/11] DRM driver for fbdev devices Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 01/11] drm/fbdevdrm: Add driver skeleton Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 02/11] drm/fbdevdrm: Add fbdevdrm device Thomas Zimmermann
2019-03-26 16:03 ` Adam Jackson
2019-03-27 7:55 ` Thomas Zimmermann
2019-03-27 8:03 ` Daniel Vetter
2019-03-26 9:17 ` [PATCH 03/11] drm/fbdevdrm: Add memory management Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 04/11] drm/fbdevdrm: Add file operations Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 05/11] drm/fbdevdrm: Add GEM and dumb interfaces Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 06/11] drm/fbdevdrm: Add modesetting infrastructure Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 07/11] drm/fbdevdrm: Add DRM <-> fbdev pixel-format conversion Thomas Zimmermann
2019-03-26 16:29 ` Ville Syrjälä
2019-03-27 8:28 ` Thomas Zimmermann
2019-03-27 10:00 ` Ville Syrjälä
2019-03-26 9:17 ` [PATCH 08/11] drm/fbdevdrm: Add mode conversion DRM <-> fbdev Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 09/11] drm/fbdevdrm: Add primary plane Thomas Zimmermann
2019-03-26 13:33 ` Mathieu Malaterre
2019-03-26 13:57 ` Thomas Zimmermann
2019-03-27 9:37 ` Thomas Zimmermann
2019-04-02 7:08 ` Mathieu Malaterre
2019-03-26 9:17 ` [PATCH 10/11] drm/fbdevdrm: Add CRTC Thomas Zimmermann
2019-03-26 9:17 ` [PATCH 11/11] drm/fbdevdrm: Detect and validate display modes Thomas Zimmermann
2019-03-26 16:47 ` Ville Syrjälä
2019-03-26 18:20 ` Daniel Vetter
2019-03-27 8:31 ` Thomas Zimmermann
2019-03-26 14:53 ` [RFC][PATCH 00/11] DRM driver for fbdev devices Daniel Vetter
2019-03-27 9:10 ` Thomas Zimmermann
2019-03-27 9:41 ` Daniel Vetter
2019-03-27 9:55 ` Michel Dänzer [this message]
2019-03-27 10:58 ` Daniel Vetter
2019-03-27 14:46 ` Thomas Zimmermann
2019-03-27 17:05 ` Daniel Vetter
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