From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH] drm/panel: lvds: Handle the optional regulator case properly Date: Thu, 11 Jan 2018 23:30:59 +0200 Message-ID: <4247973.Y2IEusv7l3@avalon> References: <20180110155941.16109-1-maxime.ripard@free-electrons.com> <1944741.zEkzsdPTSS@avalon> <87zi5kii00.fsf@intel.com> 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 284FD6E461 for ; Thu, 11 Jan 2018 21:31:01 +0000 (UTC) In-Reply-To: <87zi5kii00.fsf@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Jani Nikula Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Mark Brown , Daniel Vetter , Maxime Ripard List-Id: dri-devel@lists.freedesktop.org SGkgSmFuaSwKCk9uIFRodXJzZGF5LCAxMSBKYW51YXJ5IDIwMTggMTY6MzE6NTkgRUVUIEphbmkg TmlrdWxhIHdyb3RlOgo+IE9uIFRodSwgMTEgSmFuIDIwMTgsIExhdXJlbnQgUGluY2hhcnQgd3Jv dGU6Cj4gPiBNeSBwcmVmZXJlbmNlLCBob3dldmVyLCB3b3VsZCBiZSBmb3IgZGV2bV9yZWd1bGF0 b3JfZ2V0X29wdGlvbmFsKCkgdG8KPiA+IHJldHVybiBOVUxMIHdoZW4gbm8gcmVndWxhdG9yIGlz IHByZXNlbnQuIFRoZSBjdXJyZW50IGltcGxlbWVudGF0aW9uCj4gPiByZXR1cm5zIC1FTk9ERVYg aW4gbXVsdGlwbGUgY2FzZXMsIG1ha2luZyBpdCBpbXBvc3NpYmxlIHRvIHByb3Blcmx5Cj4gPiBk aXNjcmltaW5hdGUgYmV0d2VlbiBoYXZpbmcgbm8gcmVndWxhdG9yIGFuZCBub3QgYmVpbmcgYWJs ZSB0byBnZXQgdGhlCj4gPiByZWd1bGF0b3IgZHVlIHRvIGFuIGVycm9yLgo+IAo+IEp1c3QgYSB3 b3JkIG9mIHdhcm5pbmcsIElTX0VSUihOVUxMKSBpcyBmYWxzZSwgYW5kIHlvdXIgcHJvcG9zZWQg Y2hhbmdlCj4gd291bGQgYXBwYXJlbnRseSByZXF1aXJlIHF1aXRlIGEgY2h1cm4gYWxsIG92ZXIg dGhlIGtlcm5lbC4KClRoYXQncyBjb3JyZWN0LCBidXQgSSBzdGlsbCB0aGluayB0aGF0IHdvdWxk IG1ha2UgdGhlIEFQSSBjbGVhcmVyLiBJIGRvbid0IAp3YW50IHRvIGJsb2NrIHRoaXMgcGF0Y2gg dW50aWwgd2UgbWFrZSBzdWNoIGEgY2hhbmdlLCBidXQgaXQncyBhIGdvb2QgCm9wcG9ydHVuaXR5 IHRvIGRpc2N1c3MgaXQuIEknZCBsaWtlIHRvIGtub3cgd2hhdCBNYXJrJ3Mgb3BpbmlvbiBpcy4K Ci0tIApSZWdhcmRzLAoKTGF1cmVudCBQaW5jaGFydAoKX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxA bGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxt YW4vbGlzdGluZm8vZHJpLWRldmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933269AbeAKVbD (ORCPT + 1 other); Thu, 11 Jan 2018 16:31:03 -0500 Received: from galahad.ideasonboard.com ([185.26.127.97]:51479 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932603AbeAKVbB (ORCPT ); Thu, 11 Jan 2018 16:31:01 -0500 From: Laurent Pinchart To: Jani Nikula Cc: Maxime Ripard , Daniel Vetter , Sean Paul , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Mark Brown Subject: Re: [PATCH] drm/panel: lvds: Handle the optional regulator case properly Date: Thu, 11 Jan 2018 23:30:59 +0200 Message-ID: <4247973.Y2IEusv7l3@avalon> Organization: Ideas on Board Oy In-Reply-To: <87zi5kii00.fsf@intel.com> References: <20180110155941.16109-1-maxime.ripard@free-electrons.com> <1944741.zEkzsdPTSS@avalon> <87zi5kii00.fsf@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Hi Jani, On Thursday, 11 January 2018 16:31:59 EET Jani Nikula wrote: > On Thu, 11 Jan 2018, Laurent Pinchart wrote: > > My preference, however, would be for devm_regulator_get_optional() to > > return NULL when no regulator is present. The current implementation > > returns -ENODEV in multiple cases, making it impossible to properly > > discriminate between having no regulator and not being able to get the > > regulator due to an error. > > Just a word of warning, IS_ERR(NULL) is false, and your proposed change > would apparently require quite a churn all over the kernel. That's correct, but I still think that would make the API clearer. I don't want to block this patch until we make such a change, but it's a good opportunity to discuss it. I'd like to know what Mark's opinion is. -- Regards, Laurent Pinchart