From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Jacques Hiblot Subject: Re: [PATCH 3/4] backlight: add led-backlight driver Date: Fri, 5 Jul 2019 12:33:33 +0200 Message-ID: <6c21af33-8c3b-58a8-0a1b-f85fb9f80050@ti.com> References: <20190701151423.30768-1-jjhiblot@ti.com> <20190701151423.30768-4-jjhiblot@ti.com> <20190702095434.d426lichmaffz7a5@holly.lan> <531e237c-b570-5270-6fc3-6629a8bf7acd@ti.com> <20190702130434.frbx7jkec27ejbpo@holly.lan> <72c45311-c710-dc2d-a6de-68e44ea8436a@ti.com> <20190703094457.etmbbjhhssbdkveo@holly.lan> <20190705100851.zn2jkipj4fxq5we6@devuan> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20190705100851.zn2jkipj4fxq5we6@devuan> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Pavel Machek Cc: mark.rutland@arm.com, Daniel Thompson , jingoohan1@gmail.com, tomi.valkeinen@ti.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, robh+dt@kernel.org, jacek.anaszewski@gmail.com, lee.jones@linaro.org, linux-leds@vger.kernel.org, dmurphy@ti.com List-Id: linux-leds@vger.kernel.org UGF2ZWwKCk9uIDA1LzA3LzIwMTkgMTI6MDgsIFBhdmVsIE1hY2hlayB3cm90ZToKPiBIaSEKPgo+ Pj4+PiBBbHNvIHN0aWxsIHJlbGV2YW50IGlzIHdoZXRoZXIgdGhlIExFRCBkZXZpY2UgaXMgYmVp bmcgY29ycmVjdGx5Cj4+Pj4+IG1vZGVsbGVkIGlmIHRoZSBhY3Qgb2YgdHVybmluZyBvbiB0aGUg TEVEIGRvZXNuJ3QsIGluIGZhY3QsIHR1cm4gdGhlIExFRAo+Pj4+PiBvbi4gSXMgaXQgKnJlYWxs eSogYSBjb3JyZWN0IGltcGxlbWVudGF0aW9uIG9mIGFuIExFRCBkZXZpY2UgdGhhdAo+Pj4+PiBz ZXR0aW5nIGl0IHRvIExFRF9GVUxMIHVzaW5nIHN5c2ZzIGRvZXNuJ3QgY2F1c2UgaXQgdG8gbGln aHQgdXA/Cj4+Pj4gV2hhdCBJIHVuZGVyc3Rvb2QgZnJvbSB0aGUgZGlzY3Vzc2lvbiBiZXR3ZWVu IFJvYiBhbmQgVG9taSBpcyB0aGF0IHRoZQo+Pj4+IGNoaWxkLW5vZGUgb2YgdGhlIExFRCBjb250 cm9sbGVyIHNob3VsZCBiZSBjb25zaWRlcmVkIGEgYmFja2xpZ2h0IGRldmljZSwKPj4+PiBub3Qg YSBzaW1wbGUgTEVELiBJJ20gbm90IHN1cmUgaWYgdGhlIHN5c2ZzIGludGVyZmFjZSBpcyBzdGls bCByZWxldmFudCBpbgo+Pj4+IHRoYXQgY2FzZS4gTWF5YmUgaXQgc2hvdWxkIGp1c3QgYmUgZGlz YWJsZWQgYnkgdGhlIGJhY2tsaWdodCBkcml2ZXIKPj4+PiAocG9zc2libGUgd2l0aCBsZWRfc3lz ZnNfZGlzYWJsZSgpKQo+Pj4gbGVkX3N5c2ZzX2Rpc2FibGUoKSBzb3VuZHMgbGlrZSBhIHNlbnNp YmxlIGNoYW5nZSBidXQgdGhhdCdzIG5vdCBxdWl0ZQo+Pj4gd2hhdCBJIG1lYW4uCj4+Pgo+Pj4g SXQgaXMgbW9yZSBhIHRob3VnaHQgZXhwZXJpbWVudCB0byBzZWUgaWYgdGhlIHBvd2VyIGNvbnRy b2wgKnNob3VsZCogYmUKPj4+IGltcGxlbWVudGVkIGJ5IHRoZSBiYWNrbGlnaHQuIENvbnNpZGVy IHdoYXQgaGFwcGVucyBpZiB3ZSAqZG9uJ3QqCj4+PiBlbmFibGUgQ09ORklHX0JBQ0tMSUdIVF9M RUQgaW4gdGhlIGtlcm5lbDogd2Ugd291bGQgc3RpbGwgaGF2ZSBhbiBMRUQKPj4+IGRldmljZSBh bmQgaXQgd291bGQgbm90IHdvcmsgY29ycmVjdGx5Lgo+Pj4KPj4+IEluIG90aGVyIHdvcmRzIEkg bmFpdmVseSBleHBlY3QgdHVybmluZyBvbiBhbiBMRUQgdXNpbmcgdGhlIExFRCBBUEkKPj4+IChh bnkgb2YgdGhlbSwgc3lzZnMgb3Iga2VybmVsKSB0byByZXN1bHQgaW4gdGhlIExFRCB0dXJuaW5n IG9uLgo+Pj4gSW1wbGVtZW50aW5nIGEgd29ya2Fyb3VuZCBpbiB0aGUgY2xpZW50IGZvciB3aGF0 IGFwcGVhcnMgdG8gYmUKPj4+IHNvbWV0aGluZyBtaXNzaW5nIGluIHRoZSBMRUQgZHJpdmVyIHN0 cmlrZXMgbWUgYXMgb2RkLiBXaHkgc2hvdWxkbid0Cj4+PiB0aGUgcmVndWxhdG9yIGJlIG1hbmFn ZWQgaW4gdGhlIExFRCBkcml2ZXI/Cj4+IEkgc2VlIHlvdXIgcG9pbnQuIEluZGVlZCBoYXZpbmcg dGhlIHJlZ3VsYXRvciBoYW5kbGVkIGluIHRoZSBMRUQtY29yZSBtYWtlcwo+PiBzZW5zZSBpbiBh IGxvdCBvZiBzaXR1YXRpb25zCj4+Cj4+IEknbGwgdGhpbmsgYWJvdXQgaXQuCj4gRm9yIHRoZSBy ZWNvcmQsIEkgYWxzbyBiZWxpZXZlIHJlZ3VsYXRvciBhbmQgZW5hYmxlIGdwaW8gc2hvdWxkIGJl Cj4gaGFuZGxlZCBpbiB0aGUgY29yZS4KCkkgYW0gd29ya2luZyBvbiBhZGRpbmcgdGhlIHJlZ3Vs YXRvciB0byB0aGUgbGVkIGNvcmUuCgpJIGRvbid0IHJlYWxseSB3YW50IHRvIGFkZCBhIEdQSU8g ZW5hYmxlIHRvIHRoZSBjb3JlIHRob3VnaC4gSWYgbmVlZGVkIAppdCBjYW4gYmUgZGVzY3JpYmVk IGFzIGEgR1BJTy1lbmFibGVkIHJlZ3VsYXRvciB1cCgvZG93bilzdHJlYW0gdGhlIApyZWd1bGFy IHJlZ3VsYXRvci4KCkpKCgoKPgo+IAkJCQkJCQkJCVBhdmVsCj4gUFMgcGxlYXNlIHRyaW0gZG93 biB0aGUgcXVvdGVkIHRleHQuCQkJCQkJCQkJCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRldmVsQGxpc3Rz LmZyZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xp c3RpbmZvL2RyaS1kZXZlbA== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D2F0C46499 for ; 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Fri, 5 Jul 2019 05:33:39 -0500 Received: from DFLE104.ent.ti.com (10.64.6.25) by DFLE109.ent.ti.com (10.64.6.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Fri, 5 Jul 2019 05:33:38 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DFLE104.ent.ti.com (10.64.6.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5 via Frontend Transport; Fri, 5 Jul 2019 05:33:38 -0500 Received: from [10.250.97.31] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id x65AXa3F125307; Fri, 5 Jul 2019 05:33:36 -0500 Subject: Re: [PATCH 3/4] backlight: add led-backlight driver To: Pavel Machek CC: Daniel Thompson , , , , , , , , , , References: <20190701151423.30768-1-jjhiblot@ti.com> <20190701151423.30768-4-jjhiblot@ti.com> <20190702095434.d426lichmaffz7a5@holly.lan> <531e237c-b570-5270-6fc3-6629a8bf7acd@ti.com> <20190702130434.frbx7jkec27ejbpo@holly.lan> <72c45311-c710-dc2d-a6de-68e44ea8436a@ti.com> <20190703094457.etmbbjhhssbdkveo@holly.lan> <20190705100851.zn2jkipj4fxq5we6@devuan> From: Jean-Jacques Hiblot Message-ID: <6c21af33-8c3b-58a8-0a1b-f85fb9f80050@ti.com> Date: Fri, 5 Jul 2019 12:33:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <20190705100851.zn2jkipj4fxq5we6@devuan> Content-Type: text/plain; charset="UTF-8"; format="flowed" Content-Transfer-Encoding: 7bit Content-Language: en-US X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-leds-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org Message-ID: <20190705103333.r1GDsOwRttBnf_7ka0oy0l5QtUXEeKwfQ9RCD0lU4-M@z> Pavel On 05/07/2019 12:08, Pavel Machek wrote: > Hi! > >>>>> Also still relevant is whether the LED device is being correctly >>>>> modelled if the act of turning on the LED doesn't, in fact, turn the LED >>>>> on. Is it *really* a correct implementation of an LED device that >>>>> setting it to LED_FULL using sysfs doesn't cause it to light up? >>>> What I understood from the discussion between Rob and Tomi is that the >>>> child-node of the LED controller should be considered a backlight device, >>>> not a simple LED. I'm not sure if the sysfs interface is still relevant in >>>> that case. Maybe it should just be disabled by the backlight driver >>>> (possible with led_sysfs_disable()) >>> led_sysfs_disable() sounds like a sensible change but that's not quite >>> what I mean. >>> >>> It is more a thought experiment to see if the power control *should* be >>> implemented by the backlight. Consider what happens if we *don't* >>> enable CONFIG_BACKLIGHT_LED in the kernel: we would still have an LED >>> device and it would not work correctly. >>> >>> In other words I naively expect turning on an LED using the LED API >>> (any of them, sysfs or kernel) to result in the LED turning on. >>> Implementing a workaround in the client for what appears to be >>> something missing in the LED driver strikes me as odd. Why shouldn't >>> the regulator be managed in the LED driver? >> I see your point. Indeed having the regulator handled in the LED-core makes >> sense in a lot of situations >> >> I'll think about it. > For the record, I also believe regulator and enable gpio should be > handled in the core. I am working on adding the regulator to the led core. I don't really want to add a GPIO enable to the core though. If needed it can be described as a GPIO-enabled regulator up(/down)stream the regular regulator. JJ > > Pavel > PS please trim down the quoted text.