From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Sekhar Nori <nsekhar@ti.com>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Kevin Hilman <khilman@baylibre.com>,
Michael Turquette <mturquette@baylibre.com>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Mark Rutland <mark.rutland@arm.com>,
Peter Ujfalusi <peter.ujfalusi@ti.com>,
Russell King <linux@armlinux.org.uk>,
Karl Beldan <karl.beldan@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
arm-soc <linux-arm-kernel@lists.infradead.org>,
linux-drm <dri-devel@lists.freedesktop.org>,
linux-devicetree <devicetree@vger.kernel.org>,
Jyri Sarha <jsarha@ti.com>, David Airlie <airlied@linux.ie>,
Maxime Ripard <maxime.ripard@free-electrons.com>,
Karl Beldan <kbeldan@baylibre.com>
Subject: Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller
Date: Mon, 17 Oct 2016 15:44:48 +0300 [thread overview]
Message-ID: <1615142.iysWriV8vb@avalon> (raw)
In-Reply-To: <daf49046-ad0a-d9e2-d744-1e06085c6585@ti.com>
Hi Tomi,
On Monday 17 Oct 2016 15:29:23 Tomi Valkeinen wrote:
> On 17/10/16 14:40, Laurent Pinchart wrote:
> > On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
> >> On 17/10/16 10:12, Sekhar Nori wrote:
> >>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
> >>>> On 15/10/16 20:42, Sekhar Nori wrote:
> >>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
> >>>>>> b/arch/arm/boot/dts/da850.dtsi
> >>>>>> index f79e1b9..32908ae 100644
> >>>>>> --- a/arch/arm/boot/dts/da850.dtsi
> >>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
> >>>>>> @@ -399,6 +420,14 @@
> >>>>>> <&edma0 0 1>;
> >>>>>> dma-names = "tx", "rx";
> >>>>>> };
> >>>>>> +
> >>>>>> + display: display@213000 {
> >>>>>> + compatible = "ti,am33xx-tilcdc", "ti,da850-
tilcdc";
> >>>>>
> >>>>> This should instead be:
> >>>>>
> >>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
> >>>>>
> >>>>> as the closest match should appear first in the list.
> >>>>
> >>>> Actually I don't think that's correct. The LCDC on da850 is not
> >>>> compatible with the LCDC on AM335x. I think it should be just
> >>>> "ti,da850-tilcdc".
> >>>
> >>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
> >>> the case, I wonder how the patch passed testing. Bartosz?
> >>
> >> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
> >> similar, but different.
> >>
> >> The driver gets the version number from LCDC's register, and acts based
> >> on that, so afaik the compatible string doesn't really affect the
> >> functionality (as long as it matches).
> >>
> >> But even if it works with the current driver, I don't think
> >> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.
> >
> > If the hardware provides IP revision information, how about just "ti,lcdc"
> > ?
>
> Maybe, and I agree that's the "correct" way, but looking at the history,
> it's not just once or twice when we've suddenly found out some
> difference or bug or such in an IP revision, or the integration to a
> SoC, that can't be found based on the IP revision.
>
> That's why I feel it's usually safer to have the SoC revision there in
> the compatible string.
>
> That said, we have only a few different old SoCs with LCDC (compared to,
> say, OMAP DSS) so in this case perhaps just "ti,lcdc" would be fine.
You obviously know more than I do on this topic so I'll trust your opinion. If
the version register isn't enough I'm fine with multiple compatible strings.
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2016-10-17 12:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-05 13:05 [PATCH 0/2] ARM: davinci: initial infrastructure for LCDC Bartosz Golaszewski
2016-10-05 13:05 ` [PATCH 1/2] ARM: davinci: da8xx-dt: add OF_DEV_AUXDATA entry for lcdc Bartosz Golaszewski
2016-10-05 13:05 ` [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Bartosz Golaszewski
2016-10-15 17:42 ` Sekhar Nori
2016-10-15 19:40 ` Bartosz Golaszewski
2016-10-17 5:56 ` Tomi Valkeinen
2016-10-17 7:12 ` Sekhar Nori
2016-10-17 7:28 ` Bartosz Golaszewski
2016-10-17 7:33 ` Tomi Valkeinen
2016-10-17 11:40 ` Laurent Pinchart
2016-10-17 12:29 ` Tomi Valkeinen
2016-10-17 12:44 ` Laurent Pinchart [this message]
2016-10-17 14:01 ` Bartosz Golaszewski
2016-10-20 10:07 ` Sekhar Nori
2016-10-20 10:21 ` Tomi Valkeinen
2016-10-20 10:29 ` Sekhar Nori
2016-10-05 15:16 ` [PATCH 0/2] ARM: davinci: initial infrastructure for LCDC Karl Beldan
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