From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from galahad.ideasonboard.com ([185.26.127.97]:58102 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032793AbeBNQvc (ORCPT ); Wed, 14 Feb 2018 11:51:32 -0500 From: Laurent Pinchart To: Laurent Pinchart Cc: Sergei Shtylyov , David Airlie , dri-devel@lists.freedesktop.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH 1/2] drm: rcar-du: lvds: fix LVDS startup on R-Car gen3 Date: Wed, 14 Feb 2018 18:52:05 +0200 Message-ID: <379662807.WmKFOaE3uo@avalon> In-Reply-To: <35260661.mJIny8zrSv@avalon> References: <20180112201550.368547609@cogentembedded.com> <27ae5c72-b774-1af5-ae99-65009c2b6416@cogentembedded.com> <35260661.mJIny8zrSv@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 Sergei, On Tuesday, 16 January 2018 17:42:41 EET Laurent Pinchart wrote: > On Saturday, 13 January 2018 11:25:31 EET Sergei Shtylyov wrote: > > On 1/13/2018 1:15 AM, Laurent Pinchart wrote: > >>>> According to the latest revisions of the R-Car gen3 manual, the LVDS > >>>> mode must be set before the LVDS I/O pins are enabled, not after -- > >>>> fix the gen3 LVDS startup sequence accordingly... > >>>> > >>>> While at it, also fix the comment preceding the first LVDCR0 write > >>>> in the R-Car gen2 startup code that still talks about hardcoding the > >>>> LVDS mode 0... > >>> > >>> How about fixing that in patch 2/2 that touches the Gen2 initialization > >>> sequence ? I think I'd even go as far as squashing both patches, I > >>> don't think there's a need to split them. > >>> > >>>> Fixes: e947eccbeba4 ("drm: rcar-du: Add support for LVDS mode > >>>> selection") > >>>> Signed-off-by: Sergei Shtylyov > >>> > >>> Is this really needed ? Does it fix a problem you've experienced, or is > >>> it theoretical only ? The mode shouldn't matter before the LVDS > >>> internal logic is turned on. Unless there's a real issue I'm not sure we > >>> should make the code more complex. > >> > >> Furthermore the datasheet states > >> > >> "3. This refers to settings other than those that are concerned with > >> LVDS-IF startup. These items may be set while waiting for the conditions > >> of step 6 to be met." > > > > Ah, I hadn't paid much attention to this note. Howeve, it seems quite > > vague to me... and there's no condition in step 6. ;-) > > Lots of bits and pieces are lost in translation yes :-) > > >> Doesn't this mean that the mode and input selector don't have to be set > >> as the very first step, but can be programmed at any point before > >> starting the LVDS encoder through the PWD bit (on Gen3) or the PLLON bit > >> (on Gen2) ? > > > > Frankly speaking, I don't know how to interpret that note... > > My understanding is that the parameters can be programmed at any time before > step 6. The fact that the current code works seems to confirm that > interpretation. We could ask Renesas for a confirmation if you want. I've received feedback, and while it wasn't clear what the not really means, Renesas recommends following the documented startup sequence (I'm still not sure it's really needed, but that's a different story). I'll thus rebase this patch and repost it, and take it in my tree if you're fine with the result. -- Regards, Laurent Pinchart From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH 1/2] drm: rcar-du: lvds: fix LVDS startup on R-Car gen3 Date: Wed, 14 Feb 2018 18:52:05 +0200 Message-ID: <379662807.WmKFOaE3uo@avalon> References: <20180112201550.368547609@cogentembedded.com> <27ae5c72-b774-1af5-ae99-65009c2b6416@cogentembedded.com> <35260661.mJIny8zrSv@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 [185.26.127.97]) by gabe.freedesktop.org (Postfix) with ESMTPS id B79856E404 for ; Wed, 14 Feb 2018 16:51:32 +0000 (UTC) In-Reply-To: <35260661.mJIny8zrSv@avalon> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Laurent Pinchart Cc: David Airlie , linux-renesas-soc@vger.kernel.org, dri-devel@lists.freedesktop.org, Sergei Shtylyov List-Id: dri-devel@lists.freedesktop.org SGkgU2VyZ2VpLAoKT24gVHVlc2RheSwgMTYgSmFudWFyeSAyMDE4IDE3OjQyOjQxIEVFVCBMYXVy ZW50IFBpbmNoYXJ0IHdyb3RlOgo+IE9uIFNhdHVyZGF5LCAxMyBKYW51YXJ5IDIwMTggMTE6MjU6 MzEgRUVUIFNlcmdlaSBTaHR5bHlvdiB3cm90ZToKPiA+IE9uIDEvMTMvMjAxOCAxOjE1IEFNLCBM YXVyZW50IFBpbmNoYXJ0IHdyb3RlOgo+ID4+Pj4gQWNjb3JkaW5nIHRvIHRoZSBsYXRlc3QgcmV2 aXNpb25zIG9mIHRoZSBSLUNhciBnZW4zIG1hbnVhbCwgdGhlIExWRFMKPiA+Pj4+IG1vZGUgbXVz dCBiZSBzZXQgYmVmb3JlIHRoZSBMVkRTIEkvTyBwaW5zIGFyZSBlbmFibGVkLCBub3QgYWZ0ZXIg LS0gCj4gPj4+PiBmaXggdGhlIGdlbjMgTFZEUyBzdGFydHVwIHNlcXVlbmNlIGFjY29yZGluZ2x5 Li4uCj4gPj4+PiAKPiA+Pj4+IFdoaWxlICBhdCBpdCwgIGFsc28gZml4IHRoZSBjb21tZW50ICBw cmVjZWRpbmcgdGhlIGZpcnN0IExWRENSMCB3cml0ZQo+ID4+Pj4gaW4gdGhlIFItQ2FyIGdlbjIg c3RhcnR1cCBjb2RlIHRoYXQgc3RpbGwgdGFsa3MgYWJvdXQgaGFyZGNvZGluZyB0aGUKPiA+Pj4+ IExWRFMgbW9kZSAwLi4uCj4gPj4+IAo+ID4+PiBIb3cgYWJvdXQgZml4aW5nIHRoYXQgaW4gcGF0 Y2ggMi8yIHRoYXQgdG91Y2hlcyB0aGUgR2VuMiBpbml0aWFsaXphdGlvbgo+ID4+PiBzZXF1ZW5j ZSA/IEkgdGhpbmsgSSdkIGV2ZW4gZ28gYXMgZmFyIGFzIHNxdWFzaGluZyBib3RoIHBhdGNoZXMs IEkKPiA+Pj4gZG9uJ3QgdGhpbmsgdGhlcmUncyBhIG5lZWQgdG8gc3BsaXQgdGhlbS4KPiA+Pj4g Cj4gPj4+PiBGaXhlczogZTk0N2VjY2JlYmE0ICgiZHJtOiByY2FyLWR1OiBBZGQgc3VwcG9ydCBm b3IgTFZEUyBtb2RlCj4gPj4+PiBzZWxlY3Rpb24iKQo+ID4+Pj4gU2lnbmVkLW9mZi1ieTogU2Vy Z2VpIFNodHlseW92IDxzZXJnZWkuc2h0eWx5b3ZAY29nZW50ZW1iZWRkZWQuY29tPgo+ID4+PiAK PiA+Pj4gSXMgdGhpcyByZWFsbHkgbmVlZGVkID8gRG9lcyBpdCBmaXggYSBwcm9ibGVtIHlvdSd2 ZSBleHBlcmllbmNlZCwgb3IgaXMKPiA+Pj4gaXQgdGhlb3JldGljYWwgb25seSA/IFRoZSBtb2Rl IHNob3VsZG4ndCBtYXR0ZXIgYmVmb3JlIHRoZSBMVkRTCj4gPj4+IGludGVybmFsIGxvZ2ljIGlz IHR1cm5lZCBvbi4gVW5sZXNzIHRoZXJlJ3MgYSByZWFsIGlzc3VlIEknbSBub3Qgc3VyZSB3ZQo+ ID4+PiBzaG91bGQgbWFrZSB0aGUgY29kZSBtb3JlIGNvbXBsZXguCj4gPj4gCj4gPj4gRnVydGhl cm1vcmUgdGhlIGRhdGFzaGVldCBzdGF0ZXMKPiA+PiAKPiA+PiAiMy4gVGhpcyByZWZlcnMgdG8g c2V0dGluZ3Mgb3RoZXIgdGhhbiB0aG9zZSB0aGF0IGFyZSBjb25jZXJuZWQgd2l0aAo+ID4+IExW RFMtSUYgc3RhcnR1cC4gVGhlc2UgaXRlbXMgbWF5IGJlIHNldCB3aGlsZSB3YWl0aW5nIGZvciB0 aGUgY29uZGl0aW9ucwo+ID4+IG9mIHN0ZXAgNiB0byBiZSBtZXQuIgo+ID4gCj4gPiBBaCwgSSBo YWRuJ3QgcGFpZCBtdWNoIGF0dGVudGlvbiB0byB0aGlzIG5vdGUuIEhvd2V2ZSwgaXQgc2VlbXMg cXVpdGUKPiA+IHZhZ3VlIHRvIG1lLi4uIGFuZCB0aGVyZSdzIG5vIGNvbmRpdGlvbiBpbiBzdGVw IDYuIDstKQo+IAo+IExvdHMgb2YgYml0cyBhbmQgcGllY2VzIGFyZSBsb3N0IGluIHRyYW5zbGF0 aW9uIHllcyA6LSkKPiAKPiA+PiBEb2Vzbid0IHRoaXMgbWVhbiB0aGF0IHRoZSBtb2RlIGFuZCBp bnB1dCBzZWxlY3RvciBkb24ndCBoYXZlIHRvIGJlIHNldAo+ID4+IGFzIHRoZSB2ZXJ5IGZpcnN0 IHN0ZXAsIGJ1dCBjYW4gYmUgcHJvZ3JhbW1lZCBhdCBhbnkgcG9pbnQgYmVmb3JlCj4gPj4gc3Rh cnRpbmcgdGhlIExWRFMgZW5jb2RlciB0aHJvdWdoIHRoZSBQV0QgYml0IChvbiBHZW4zKSBvciB0 aGUgUExMT04gYml0Cj4gPj4gKG9uIEdlbjIpID8KPiA+IAo+ID4gRnJhbmtseSBzcGVha2luZywg SSBkb24ndCBrbm93IGhvdyB0byBpbnRlcnByZXQgdGhhdCBub3RlLi4uCj4gCj4gTXkgdW5kZXJz dGFuZGluZyBpcyB0aGF0IHRoZSBwYXJhbWV0ZXJzIGNhbiBiZSBwcm9ncmFtbWVkIGF0IGFueSB0 aW1lIGJlZm9yZQo+IHN0ZXAgNi4gVGhlIGZhY3QgdGhhdCB0aGUgY3VycmVudCBjb2RlIHdvcmtz IHNlZW1zIHRvIGNvbmZpcm0gdGhhdAo+IGludGVycHJldGF0aW9uLiBXZSBjb3VsZCBhc2sgUmVu ZXNhcyBmb3IgYSBjb25maXJtYXRpb24gaWYgeW91IHdhbnQuCgpJJ3ZlIHJlY2VpdmVkIGZlZWRi YWNrLCBhbmQgd2hpbGUgaXQgd2Fzbid0IGNsZWFyIHdoYXQgdGhlIG5vdCByZWFsbHkgbWVhbnMs IApSZW5lc2FzIHJlY29tbWVuZHMgZm9sbG93aW5nIHRoZSBkb2N1bWVudGVkIHN0YXJ0dXAgc2Vx dWVuY2UgKEknbSBzdGlsbCBub3QgCnN1cmUgaXQncyByZWFsbHkgbmVlZGVkLCBidXQgdGhhdCdz IGEgZGlmZmVyZW50IHN0b3J5KS4gSSdsbCB0aHVzIHJlYmFzZSB0aGlzIApwYXRjaCBhbmQgcmVw b3N0IGl0LCBhbmQgdGFrZSBpdCBpbiBteSB0cmVlIGlmIHlvdSdyZSBmaW5lIHdpdGggdGhlIHJl c3VsdC4KCi0tIApSZWdhcmRzLAoKTGF1cmVudCBQaW5jaGFydAoKX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmkt ZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3Jn L21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVsCg==