From: Sascha Hauer <s.hauer@pengutronix.de>
To: Dave Airlie <airlied@gmail.com>
Cc: kernel@pengutronix.de, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 09/20] drm fb_helper: use lists for crtcs.
Date: Mon, 6 Feb 2012 12:08:22 +0100 [thread overview]
Message-ID: <20120206110822.GK1990@pengutronix.de> (raw)
In-Reply-To: <CAPM=9tzcZcZMiNsZ8oLaeU2hQ+T5=RQe91dWq=MwTnegexRq7g@mail.gmail.com>
On Sat, Feb 04, 2012 at 11:21:34AM +0000, Dave Airlie wrote:
> On Sat, Feb 4, 2012 at 10:47 AM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > On Fri, Feb 03, 2012 at 10:04:27AM +0000, Dave Airlie wrote:
> >> On Wed, Feb 1, 2012 at 10:38 AM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >> > The fb helper uses fixed size arrays for the associated crtcs.
> >> > This is an unnecessary limitation, so instead use a list to
> >> > store the crtcs and allocate them dynamically.
> >>
> >> I need more reasons on why this is a unnecessary limitation, for what?
> >>
> >> Its a lot less cache friendly to use a linked list here for not much gain,
> >
> > How often do you change modes? This code is run when the user changes
> > virtual terminals, which is not very performance critical.
>
> But why make it worse unless you have a good reason?
>
> > I am working on a mid layer to connect simple framebuffer devices to
> > kms and it would be convenient to just add a crtc to a drm device once
> > it appears. This works fine for connectors and encoders, why not also
> > for crtcs?
>
> I'd like to see the midlayer before changing the core too much, I hate
> midlayers as they always cause more pain in the long run than they
> solve,
> the DRM is one of the worst examples of midlayer design and I'd rather
> not propogate it any further.
>
> Hopefully you meant to say you are working on a set of helper
> functions that kms drivers for simple framebuffers can use
midlayer is a tainted word and I regret calling it like this right
after sending my mail. Let's call it helper then ;)
> , btw what
> is going to count as a simple framebuffer device? 1 crtc/connector?
It's not limited in the count of crtcs/connectors/encoders.
> I've got to write a bunch of "simple" kms drivers but I'd really
> rather this developed the other way. Write a drivers for two simple
> devices, then carve the common code into helpers.
My goal is to write a driver for the i.MX IPU driver. I realized that
I had to duplicate most of the exynos driver. Having written several
framebuffer drivers (for i.MX1, netx, i.MX28) I know that all these
devices are not very different, so my code is written with having
these kind of devices in my mind.
Anyway, my code does not need this particular patch, so we can delay
(or drop) it.
Sascha
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next prev parent reply other threads:[~2012-02-06 11:08 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 10:38 [PATCH] drm cleanup patches Sascha Hauer
2012-02-01 10:38 ` [PATCH 01/20] drm crtc: use drm_mode_destroy instead of kfree in drm_mode_remove Sascha Hauer
2012-02-01 10:38 ` [PATCH 02/20] drm crtc: add forgotten idr cleanup functions Sascha Hauer
2012-02-01 10:38 ` [PATCH 03/20] drm drm_edit: drm modes have to be free with drm_mode_destroy Sascha Hauer
2012-02-01 10:38 ` [PATCH 04/20] drm drm_fb_helper: destroy modes Sascha Hauer
2012-02-01 10:38 ` [PATCH 05/20] drm: add proper return value for drm_mode_crtc_set_gamma_size Sascha Hauer
2012-02-01 10:38 ` [PATCH 06/20] drm fb helper: use drm_helper_connector_dpms to do dpms Sascha Hauer
2012-02-01 10:38 ` [PATCH 07/20] drm fb helper: remove unused variable conn_limit Sascha Hauer
2012-02-01 10:38 ` [PATCH 08/20] drm fb helper: remove unused variable crtc_id Sascha Hauer
2012-02-01 10:38 ` [PATCH 09/20] drm fb_helper: use lists for crtcs Sascha Hauer
2012-02-03 10:04 ` Dave Airlie
2012-02-04 10:47 ` Sascha Hauer
2012-02-04 11:21 ` Dave Airlie
2012-02-06 11:08 ` Sascha Hauer [this message]
2012-02-01 10:38 ` [PATCH 10/20] drm: remove now unused crtc_count parameter from drm_fb_helper_init Sascha Hauer
2012-02-01 10:38 ` [PATCH 11/20] drm fb helper: add the connectors inside drm_fb_helper_initial_config Sascha Hauer
2012-02-01 10:38 ` [PATCH 12/20] drm crtc_helper: use list_for_each_entry Sascha Hauer
2012-02-01 10:38 ` [PATCH 13/20] drm crtc: Fix locking comments Sascha Hauer
2012-02-01 10:38 ` [PATCH 14/20] drm: add convenience function to create an enum property Sascha Hauer
2012-02-01 11:48 ` Chris Wilson
2012-02-01 11:53 ` Sascha Hauer
2012-02-01 12:55 ` David Airlie
2012-02-01 13:05 ` Sascha Hauer
2012-02-01 14:00 ` Daniel Vetter
2012-02-03 10:08 ` Dave Airlie
2012-02-03 23:40 ` Sascha Hauer
2012-02-01 10:38 ` [PATCH 15/20] drm: add convenience function to create an range property Sascha Hauer
2012-02-01 11:34 ` Chris Wilson
2012-02-01 10:38 ` [PATCH 16/20] drm: store connector properties in list Sascha Hauer
2012-02-01 10:38 ` [PATCH 17/20] drm: remove checks for same value in set_prop Sascha Hauer
2012-02-01 11:55 ` Chris Wilson
2012-02-01 12:13 ` Sascha Hauer
2012-02-01 12:23 ` Chris Wilson
2012-02-01 10:38 ` [PATCH 18/20] drm: do not call drm_connector_property_set_value from drivers Sascha Hauer
2012-02-01 10:38 ` [PATCH 19/20] drm exynos: use drm_fb_helper_set_par directly Sascha Hauer
2012-02-02 2:25 ` Inki Dae
2012-02-01 10:38 ` [PATCH 20/20] drm: do not set fb_info->pixmap fields Sascha Hauer
2012-02-01 12:00 ` Chris Wilson
2012-02-02 14:13 ` [PATCH] drm cleanup patches Sascha Hauer
2012-02-03 10:21 ` Dave Airlie
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