From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from galahad.ideasonboard.com ([185.26.127.97]:49759 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753993AbdDEIpP (ORCPT ); Wed, 5 Apr 2017 04:45:15 -0400 From: Laurent Pinchart To: Geert Uytterhoeven Cc: DRI Development , Linux-Renesas Subject: Re: [PATCH v2 09/13] arm64: dts: r8a7795: salvator-x: Add panel backlight support Date: Wed, 05 Apr 2017 11:45:59 +0300 Message-ID: <18654178.y7VdoJ3ein@avalon> In-Reply-To: <2227128.532ZZ8dc1T@avalon> References: <1479526093-7014-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <2227128.532ZZ8dc1T@avalon> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: Hi Geert, On Monday 21 Nov 2016 11:59:47 Laurent Pinchart wrote: > On Monday 21 Nov 2016 10:23:46 Geert Uytterhoeven wrote: > > On Mon, Nov 21, 2016 at 10:19 AM, Laurent Pinchart wrote: > >> On Monday 21 Nov 2016 09:36:22 Geert Uytterhoeven wrote: > >>> On Sat, Nov 19, 2016 at 4:28 AM, Laurent Pinchart wrote: > >>>> The panel backlight is controlled through a GPIO and a PWM channel. > >>>> > >>>> --- a/arch/arm64/boot/dts/renesas/r8a7795-salvator-x.dts > >>>> +++ b/arch/arm64/boot/dts/renesas/r8a7795-salvator-x.dts > >>>> @@ -178,6 +178,16 @@ > >>>> }; > >>>> }; > >>>> }; > >>>> + > >>>> + backlight: backlight { > >>>> + compatible = "pwm-backlight"; > >>>> + pwms = <&pwm1 0 50000>; > >>>> + > >>>> + brightness-levels = <256 128 64 16 8 4 0>; > >>> > >>> Would it make sense to define more and/or linear levels? > >> > >> Possibly, this is pretty arbitrary. Linear levels might not be the best > >> option given that the human eye doesn't have a linear response to light > >> power, but we > > > > It not only depends on the human eye, but also on the backlight hardware > > (is the conversion from voltage (L_VBRT) to light linear?). > > So we need to specify transfer functions in DT ;-) > > >> could certainly have more levels. In that case I'd prefer modifying the > >> pwm- backlight DT bindings though, and specifying the PWM resolution > >> instead of discrete levels. > >> > >> Note that the LVDS panel backlight PWM control signal is multiplexed > >> with the external memory A21 signal on the Salvator-X board, with SW5 > >> selecting which how to route the signal. When using backlight control we > >> can't access the whole NOR flash anymore, so I'm not sure this patch > >> should be merged. > > > > That NOR flash is also optional, right? > > My Ex Memory Connector is not populated. > > That's correct. The Salvator-X DT file in mainline is just an example > anyway, and we should pick the most useful peripherals for that purpose. Would you like me to include this in my next Salvator-X DT patch series for upstream merge ? -- Regards, Laurent Pinchart From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH v2 09/13] arm64: dts: r8a7795: salvator-x: Add panel backlight support Date: Wed, 05 Apr 2017 11:45:59 +0300 Message-ID: <18654178.y7VdoJ3ein@avalon> References: <1479526093-7014-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <2227128.532ZZ8dc1T@avalon> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from galahad.ideasonboard.com (galahad.ideasonboard.com [IPv6:2001:4b98:dc2:45:216:3eff:febb:480d]) by gabe.freedesktop.org (Postfix) with ESMTPS id E4BE589BBD for ; Wed, 5 Apr 2017 08:45:14 +0000 (UTC) In-Reply-To: <2227128.532ZZ8dc1T@avalon> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Geert Uytterhoeven Cc: Linux-Renesas , DRI Development List-Id: dri-devel@lists.freedesktop.org SGkgR2VlcnQsCgpPbiBNb25kYXkgMjEgTm92IDIwMTYgMTE6NTk6NDcgTGF1cmVudCBQaW5jaGFy dCB3cm90ZToKPiBPbiBNb25kYXkgMjEgTm92IDIwMTYgMTA6MjM6NDYgR2VlcnQgVXl0dGVyaG9l dmVuIHdyb3RlOgo+ID4gT24gTW9uLCBOb3YgMjEsIDIwMTYgYXQgMTA6MTkgQU0sIExhdXJlbnQg UGluY2hhcnQgd3JvdGU6Cj4gPj4gT24gTW9uZGF5IDIxIE5vdiAyMDE2IDA5OjM2OjIyIEdlZXJ0 IFV5dHRlcmhvZXZlbiB3cm90ZToKPiA+Pj4gT24gU2F0LCBOb3YgMTksIDIwMTYgYXQgNDoyOCBB TSwgTGF1cmVudCBQaW5jaGFydCB3cm90ZToKPiA+Pj4+IFRoZSBwYW5lbCBiYWNrbGlnaHQgaXMg Y29udHJvbGxlZCB0aHJvdWdoIGEgR1BJTyBhbmQgYSBQV00gY2hhbm5lbC4KPiA+Pj4+IAo+ID4+ Pj4gLS0tIGEvYXJjaC9hcm02NC9ib290L2R0cy9yZW5lc2FzL3I4YTc3OTUtc2FsdmF0b3IteC5k dHMKPiA+Pj4+ICsrKyBiL2FyY2gvYXJtNjQvYm9vdC9kdHMvcmVuZXNhcy9yOGE3Nzk1LXNhbHZh dG9yLXguZHRzCj4gPj4+PiBAQCAtMTc4LDYgKzE3OCwxNiBAQAo+ID4+Pj4gICAgICAgICAgICAg ICAgICAgICAgICAgfTsKPiA+Pj4+ICAgICAgICAgICAgICAgICB9Owo+ID4+Pj4gICAgICAgICB9 Owo+ID4+Pj4gKwo+ID4+Pj4gKyAgICAgICBiYWNrbGlnaHQ6IGJhY2tsaWdodCB7Cj4gPj4+PiAr ICAgICAgICAgICAgICAgY29tcGF0aWJsZSA9ICJwd20tYmFja2xpZ2h0IjsKPiA+Pj4+ICsgICAg ICAgICAgICAgICBwd21zID0gPCZwd20xIDAgNTAwMDA+Owo+ID4+Pj4gKwo+ID4+Pj4gKyAgICAg ICAgICAgICAgIGJyaWdodG5lc3MtbGV2ZWxzID0gPDI1NiAxMjggNjQgMTYgOCA0IDA+Owo+ID4+ PiAKPiA+Pj4gV291bGQgaXQgbWFrZSBzZW5zZSB0byBkZWZpbmUgbW9yZSBhbmQvb3IgbGluZWFy IGxldmVscz8KPiA+PiAKPiA+PiBQb3NzaWJseSwgdGhpcyBpcyBwcmV0dHkgYXJiaXRyYXJ5LiBM aW5lYXIgbGV2ZWxzIG1pZ2h0IG5vdCBiZSB0aGUgYmVzdAo+ID4+IG9wdGlvbiBnaXZlbiB0aGF0 IHRoZSBodW1hbiBleWUgZG9lc24ndCBoYXZlIGEgbGluZWFyIHJlc3BvbnNlIHRvIGxpZ2h0Cj4g Pj4gcG93ZXIsIGJ1dCB3ZQo+ID4gCj4gPiBJdCBub3Qgb25seSBkZXBlbmRzIG9uIHRoZSBodW1h biBleWUsIGJ1dCBhbHNvIG9uIHRoZSBiYWNrbGlnaHQgaGFyZHdhcmUKPiA+IChpcyB0aGUgY29u dmVyc2lvbiBmcm9tIHZvbHRhZ2UgKExfVkJSVCkgdG8gbGlnaHQgbGluZWFyPykuCj4gCj4gU28g d2UgbmVlZCB0byBzcGVjaWZ5IHRyYW5zZmVyIGZ1bmN0aW9ucyBpbiBEVCA7LSkKPiAKPiA+PiBj b3VsZCBjZXJ0YWlubHkgaGF2ZSBtb3JlIGxldmVscy4gSW4gdGhhdCBjYXNlIEknZCBwcmVmZXIg bW9kaWZ5aW5nIHRoZQo+ID4+IHB3bS0gYmFja2xpZ2h0IERUIGJpbmRpbmdzIHRob3VnaCwgYW5k IHNwZWNpZnlpbmcgdGhlIFBXTSByZXNvbHV0aW9uCj4gPj4gaW5zdGVhZCBvZiBkaXNjcmV0ZSBs ZXZlbHMuCj4gPj4gCj4gPj4gTm90ZSB0aGF0IHRoZSBMVkRTIHBhbmVsIGJhY2tsaWdodCBQV00g Y29udHJvbCBzaWduYWwgaXMgbXVsdGlwbGV4ZWQKPiA+PiB3aXRoIHRoZSBleHRlcm5hbCBtZW1v cnkgQTIxIHNpZ25hbCBvbiB0aGUgU2FsdmF0b3ItWCBib2FyZCwgd2l0aCBTVzUKPiA+PiBzZWxl Y3Rpbmcgd2hpY2ggaG93IHRvIHJvdXRlIHRoZSBzaWduYWwuIFdoZW4gdXNpbmcgYmFja2xpZ2h0 IGNvbnRyb2wgd2UKPiA+PiBjYW4ndCBhY2Nlc3MgdGhlIHdob2xlIE5PUiBmbGFzaCBhbnltb3Jl LCBzbyBJJ20gbm90IHN1cmUgdGhpcyBwYXRjaAo+ID4+IHNob3VsZCBiZSBtZXJnZWQuCj4gPiAK PiA+IFRoYXQgTk9SIGZsYXNoIGlzIGFsc28gb3B0aW9uYWwsIHJpZ2h0Pwo+ID4gTXkgRXggTWVt b3J5IENvbm5lY3RvciBpcyBub3QgcG9wdWxhdGVkLgo+IAo+IFRoYXQncyBjb3JyZWN0LiBUaGUg U2FsdmF0b3ItWCBEVCBmaWxlIGluIG1haW5saW5lIGlzIGp1c3QgYW4gZXhhbXBsZQo+IGFueXdh eSwgYW5kIHdlIHNob3VsZCBwaWNrIHRoZSBtb3N0IHVzZWZ1bCBwZXJpcGhlcmFscyBmb3IgdGhh dCBwdXJwb3NlLgoKV291bGQgeW91IGxpa2UgbWUgdG8gaW5jbHVkZSB0aGlzIGluIG15IG5leHQg U2FsdmF0b3ItWCBEVCBwYXRjaCBzZXJpZXMgZm9yIAp1cHN0cmVhbSBtZXJnZSA/CgotLSAKUmVn YXJkcywKCkxhdXJlbnQgUGluY2hhcnQKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRldmVsQGxpc3RzLmZy ZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3Rp bmZvL2RyaS1kZXZlbAo=