Linux-ARM-Kernel Archive on lore.kernel.org
 help / color / Atom feed
From: Robert Chiras <robert.chiras@nxp.com>
To: "stefan@agner.ch" <stefan@agner.ch>
Cc: "marex@denx.de" <marex@denx.de>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"airlied@linux.ie" <airlied@linux.ie>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"agx@sigxcpu.org" <agx@sigxcpu.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	dl-linux-imx <linux-imx@nxp.com>,
	"daniel@ffwll.ch" <daniel@ffwll.ch>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"festevam@gmail.com" <festevam@gmail.com>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [EXT] Re: [PATCH v2 09/15] dt-bindings: display: Add max-res property for mxsfb
Date: Wed, 14 Aug 2019 12:03:51 +0000
Message-ID: <1565784231.3209.74.camel@nxp.com> (raw)
In-Reply-To: <33feedd20e0fc154c5b736f882d24569@agner.ch>

Hi Stefann,
On Mi, 2019-08-14 at 13:25 +0200, Stefan Agner wrote:
> On 2019-08-14 13:14, Robert Chiras wrote:
> > 
> > Hi Stefan,
> > On Mi, 2019-08-14 at 13:03 +0200, Stefan Agner wrote:
> > > 
> > > On 2019-08-14 12:48, Robert Chiras wrote:
> > > > 
> > > > 
> > > > Add new optional property 'max-res', to limit the maximum
> > > > supported
> > > > resolution by the MXSFB_DRM driver.
> > > I would also mention the reason why we need this.
> > > 
> > > I guess this needs a vendor prefix as well (fsl,max-res). I also
> > > would
> > > like to have the ack of the device tree folks here.
> > Rob Herring also aked be about this, and I'll copy here the reply,
> > with
> > explanations:
> > 
> > Indeed, this limitation is actually due to bandwidth limitation,
> > but
> > the problem is that this limitation comes on i.MX8M (known as
> > mScale
> > 850D), where the memory bandwidth cannot support: GPU/VPU workload
> > in
> > the same time with both DCSS driving 4k@60 and eLCDIF driving 1080p
> > @60.
> > Since eLCDIF is a secondary display we though to add the posibility
> > to
> > limit it's bandwidth by limiting the resolution.
> > If you say that more details are needed, I can add them in the
> > description.
> Oh sorry I missed that.
> 
> Rob Herring also wrote:
> > 
> > I suppose what you are after is bandwidth limits? IIRC, there's
> > already
> > some bindings expressing such limits. Also, wouldn't you need to
> > account
> > for bpp and using the 2nd plane (IIRC that there is one).
> I guess the binding he refers to is max-memory-bandwidth, which is
> used
> in multiple driver already. It makes sense to reuse this property
> instead of inventing a new set of property which is also not taking
> bpp
> into account...
Actually I saw this binding, but I thought it is strictly related to
that driver, where it is documented. Now, that you say this one is used
in many drivers (and recalling that you suggested for my 'max-res' to
add a prefix), I get it now.
> 
> The pl111 driver implements this property, it should be fairly easy
> to
> adopt that code.
Sure, I will do something similar here, too.
> 
> --
> Stefan
> 
> 
> 
> > 
> > > 
> > > 
> > > --
> > > Stefan
> > > 
> > > > 
> > > > 
> > > > 
> > > > Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
> > > > ---
> > > >  Documentation/devicetree/bindings/display/mxsfb.txt | 6 ++++++
> > > >  1 file changed, 6 insertions(+)
> > > > 
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/display/mxsfb.txt
> > > > b/Documentation/devicetree/bindings/display/mxsfb.txt
> > > > index 472e1ea..55e22ed 100644
> > > > --- a/Documentation/devicetree/bindings/display/mxsfb.txt
> > > > +++ b/Documentation/devicetree/bindings/display/mxsfb.txt
> > > > @@ -17,6 +17,12 @@ Required properties:
> > > >  Required sub-nodes:
> > > >    - port: The connection to an encoder chip.
> > > > 
> > > > +Optional properties:
> > > > +- max-res:   an array with a maximum of two integers,
> > > > representing
> > > > the
> > > > +             maximum supported resolution, in the form of
> > > > +             <maxX>, <maxY>; if one of the item is <0>, the
> > > > default
> > > > +             driver-defined maximum resolution for that axis
> > > > is
> > > > used
> > > > +
> > > >  Example:
> > > > 
> > > >       lcdif1: display-controller@2220000 {
> > Thanks,
> > Robert
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-14 10:48 [PATCH v2 00/15] Improvements and fixes for mxsfb DRM driver Robert Chiras
2019-08-14 10:48 ` [PATCH v2 01/15] drm/mxsfb: Update mxsfb to support a bridge Robert Chiras
2019-08-14 10:48 ` [PATCH v2 02/15] drm/mxsfb: Read bus flags from bridge if present Robert Chiras
2019-08-14 10:48 ` [PATCH v2 03/15] drm/mxsfb: Add defines for the rest of registers Robert Chiras
2019-08-14 10:48 ` [PATCH v2 04/15] drm/mxsfb: Reset vital register for a proper initialization Robert Chiras
2019-08-14 11:11   ` Stefan Agner
2019-08-14 11:38     ` [EXT] " Robert Chiras
2019-08-14 10:48 ` [PATCH v2 05/15] drm/mxsfb: Update register definitions using bit manipulation defines Robert Chiras
2019-08-14 10:48 ` [PATCH v2 06/15] drm/mxsfb: Update mxsfb with additional pixel formats Robert Chiras
2019-08-14 11:44   ` Daniel Stone
2019-08-14 14:58     ` [EXT] " Robert Chiras
2019-08-14 10:48 ` [PATCH v2 07/15] drm/mxsfb: Fix the vblank events Robert Chiras
2019-08-14 17:31   ` Daniel Vetter
2019-08-14 10:48 ` [PATCH v2 08/15] drm/mxsfb: Signal mode changed when bpp changed Robert Chiras
2019-08-14 10:48 ` [PATCH v2 09/15] dt-bindings: display: Add max-res property for mxsfb Robert Chiras
2019-08-14 11:03   ` Stefan Agner
2019-08-14 11:14     ` [EXT] " Robert Chiras
2019-08-14 11:25       ` Stefan Agner
2019-08-14 12:03         ` Robert Chiras [this message]
2019-08-14 10:48 ` [PATCH v2 10/15] drm/mxsfb: Add max-res property for MXSFB Robert Chiras
2019-08-14 10:48 ` [PATCH v2 11/15] drm/mxsfb: Update mxsfb to support LCD reset Robert Chiras
2019-08-14 10:48 ` [PATCH v2 12/15] drm/mxsfb: Improve the axi clock usage Robert Chiras
2019-08-14 11:06   ` Stefan Agner
2019-08-14 11:35     ` [EXT] " Robert Chiras
2019-08-14 10:48 ` [PATCH v2 13/15] drm/mxsfb: Clear OUTSTANDING_REQS bits Robert Chiras
2019-08-14 10:48 ` [PATCH v2 14/15] drm/mxsfb: Add support for horizontal stride Robert Chiras
2019-08-14 10:48 ` [PATCH v2 15/15] drm/mxsfb: Add support for live pixel format change Robert Chiras

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1565784231.3209.74.camel@nxp.com \
    --to=robert.chiras@nxp.com \
    --cc=agx@sigxcpu.org \
    --cc=airlied@linux.ie \
    --cc=daniel@ffwll.ch \
    --cc=devicetree@vger.kernel.org \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=festevam@gmail.com \
    --cc=kernel@pengutronix.de \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marex@denx.de \
    --cc=mark.rutland@arm.com \
    --cc=robh+dt@kernel.org \
    --cc=s.hauer@pengutronix.de \
    --cc=shawnguo@kernel.org \
    --cc=stefan@agner.ch \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ARM-Kernel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/0 linux-arm-kernel/git/0.git
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/1 linux-arm-kernel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ https://lore.kernel.org/linux-arm-kernel \
		linux-arm-kernel@lists.infradead.org
	public-inbox-index linux-arm-kernel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-arm-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git