From mboxrd@z Thu Jan 1 00:00:00 1970 From: vladimir_zapolskiy@mentor.com (Vladimir Zapolskiy) Date: Thu, 17 Sep 2015 00:16:00 +0300 Subject: [PATCH v3 2/2] drm: bridge/dw_hdmi: add dw hdmi i2c bus adapter support In-Reply-To: References: <1440970470-7155-1-git-send-email-vladimir_zapolskiy@mentor.com> <20150902225008.GQ21084@n2100.arm.linux.org.uk> <20150902230408.GR21084@n2100.arm.linux.org.uk> Message-ID: <55F9DC10.9020508@mentor.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Doug, On 03.09.2015 02:19, Doug Anderson wrote: > Russell, > > On Wed, Sep 2, 2015 at 4:04 PM, Russell King - ARM Linux > wrote: >>>> Also, is it appropriate to hook non-DDC devices to a DDC bus? I suspect >>>> that's asking for trouble. >>> >>> I doubt it's appropriate. Why do you ask? >> >> To find out why you want to "specify the I2C bus". >> >> Surely if we're talking about the DDC bus, we either want to use a >> separate I2C bus (in which case the HDMI DT description needs to >> specify which I2C bus to use) or we want to use the HDMI-internal >> I2C bus, which being part of the HDMI driver, the HDMI driver will >> know how to find it itself - there should be no need to put an >> explicit ddc-i2c-bus self-reference there in that case. > > Overall it comes down to bus numbering. Possibly that's a stupid > reason, but it is my reason nevertheless. this is a known issue regarding I2C bus numbering. > Specifically it significantly helps my brain process kernel log > messages if the i2c bus that's referred to "bus 5" in my SoC's user > manual shows up consistently as "i2c5" in kernel log messages. It's > helpful it it shows up as "i2c5" even if "i2c0" - "i2c4" aren't > enabled. > > That's all totally possible by using this type of syntax, like in rk3288.dtsi: > > aliases { > i2c0 = &i2c0; > i2c1 = &i2c1; > i2c2 = &i2c2; > i2c3 = &i2c3; > i2c4 = &i2c4; > i2c5 = &i2c5; > > Similarly, I'd like "bus 0" to show up as i2c0, which will happen as > you can see in the above. > > The problem is that if another bus registers itself before the SoC's > i2c0 registers itself and that bus doesn't give a number to itself > then the i2c subsystem will chose "I2C 0". ...and then when the main > SoC i2c bus registers itself it will fail because i2c0 is already > taken. > > By having a of_node for the hdmi i2c bus, we can assign a number to it like: > i2c15 = &hdmi; > > This is all described in the two links I referenced in my original reply. > > > A possible other option is to have the i2c subsystem try to start > numbering at a larger base for all automatically numbered busses > (those that didn't specify a number). Then it's more likely (though > still not guaranteed) to conflict with another bus... Could you please check if commit 03bde7c31a3 serves you? -- With best wishes, Vladimir From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Zapolskiy Subject: Re: [PATCH v3 2/2] drm: bridge/dw_hdmi: add dw hdmi i2c bus adapter support Date: Thu, 17 Sep 2015 00:16:00 +0300 Message-ID: <55F9DC10.9020508@mentor.com> References: <1440970470-7155-1-git-send-email-vladimir_zapolskiy@mentor.com> <20150902225008.GQ21084@n2100.arm.linux.org.uk> <20150902230408.GR21084@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from relay1.mentorg.com (relay1.mentorg.com [192.94.38.131]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8006D6E1E0 for ; Wed, 16 Sep 2015 14:16:05 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Doug Anderson , Russell King - ARM Linux Cc: Fabio Estevam , "dri-devel@lists.freedesktop.org" , Yakir Yang , Andy Yan , Thierry Reding , "linux-arm-kernel@lists.infradead.org" List-Id: dri-devel@lists.freedesktop.org SGkgRG91ZywKCk9uIDAzLjA5LjIwMTUgMDI6MTksIERvdWcgQW5kZXJzb24gd3JvdGU6Cj4gUnVz c2VsbCwKPiAKPiBPbiBXZWQsIFNlcCAyLCAyMDE1IGF0IDQ6MDQgUE0sIFJ1c3NlbGwgS2luZyAt IEFSTSBMaW51eAo+IDxsaW51eEBhcm0ubGludXgub3JnLnVrPiB3cm90ZToKPj4+PiBBbHNvLCBp cyBpdCBhcHByb3ByaWF0ZSB0byBob29rIG5vbi1EREMgZGV2aWNlcyB0byBhIEREQyBidXM/ICBJ IHN1c3BlY3QKPj4+PiB0aGF0J3MgYXNraW5nIGZvciB0cm91YmxlLgo+Pj4KPj4+IEkgZG91YnQg aXQncyBhcHByb3ByaWF0ZS4gIFdoeSBkbyB5b3UgYXNrPwo+Pgo+PiBUbyBmaW5kIG91dCB3aHkg eW91IHdhbnQgdG8gInNwZWNpZnkgdGhlIEkyQyBidXMiLgo+Pgo+PiBTdXJlbHkgaWYgd2UncmUg dGFsa2luZyBhYm91dCB0aGUgRERDIGJ1cywgd2UgZWl0aGVyIHdhbnQgdG8gdXNlIGEKPj4gc2Vw YXJhdGUgSTJDIGJ1cyAoaW4gd2hpY2ggY2FzZSB0aGUgSERNSSBEVCBkZXNjcmlwdGlvbiBuZWVk cyB0bwo+PiBzcGVjaWZ5IHdoaWNoIEkyQyBidXMgdG8gdXNlKSBvciB3ZSB3YW50IHRvIHVzZSB0 aGUgSERNSS1pbnRlcm5hbAo+PiBJMkMgYnVzLCB3aGljaCBiZWluZyBwYXJ0IG9mIHRoZSBIRE1J IGRyaXZlciwgdGhlIEhETUkgZHJpdmVyIHdpbGwKPj4ga25vdyBob3cgdG8gZmluZCBpdCBpdHNl bGYgLSB0aGVyZSBzaG91bGQgYmUgbm8gbmVlZCB0byBwdXQgYW4KPj4gZXhwbGljaXQgZGRjLWky Yy1idXMgc2VsZi1yZWZlcmVuY2UgdGhlcmUgaW4gdGhhdCBjYXNlLgo+IAo+IE92ZXJhbGwgaXQg Y29tZXMgZG93biB0byBidXMgbnVtYmVyaW5nLiAgUG9zc2libHkgdGhhdCdzIGEgc3R1cGlkCj4g cmVhc29uLCBidXQgaXQgaXMgbXkgcmVhc29uIG5ldmVydGhlbGVzcy4KCnRoaXMgaXMgYSBrbm93 biBpc3N1ZSByZWdhcmRpbmcgSTJDIGJ1cyBudW1iZXJpbmcuCgo+IFNwZWNpZmljYWxseSBpdCBz aWduaWZpY2FudGx5IGhlbHBzIG15IGJyYWluIHByb2Nlc3Mga2VybmVsIGxvZwo+IG1lc3NhZ2Vz IGlmIHRoZSBpMmMgYnVzIHRoYXQncyByZWZlcnJlZCB0byAiYnVzIDUiIGluIG15IFNvQydzIHVz ZXIKPiBtYW51YWwgc2hvd3MgdXAgY29uc2lzdGVudGx5IGFzICJpMmM1IiBpbiBrZXJuZWwgbG9n IG1lc3NhZ2VzLiAgSXQncwo+IGhlbHBmdWwgaXQgaXQgc2hvd3MgdXAgYXMgImkyYzUiIGV2ZW4g aWYgImkyYzAiIC0gImkyYzQiIGFyZW4ndAo+IGVuYWJsZWQuCj4gCj4gVGhhdCdzIGFsbCB0b3Rh bGx5IHBvc3NpYmxlIGJ5IHVzaW5nIHRoaXMgdHlwZSBvZiBzeW50YXgsIGxpa2UgaW4gcmszMjg4 LmR0c2k6Cj4gCj4gYWxpYXNlcyB7Cj4gICBpMmMwID0gJmkyYzA7Cj4gICBpMmMxID0gJmkyYzE7 Cj4gICBpMmMyID0gJmkyYzI7Cj4gICBpMmMzID0gJmkyYzM7Cj4gICBpMmM0ID0gJmkyYzQ7Cj4g ICBpMmM1ID0gJmkyYzU7Cj4gCj4gU2ltaWxhcmx5LCBJJ2QgbGlrZSAiYnVzIDAiIHRvIHNob3cg dXAgYXMgaTJjMCwgd2hpY2ggd2lsbCBoYXBwZW4gYXMKPiB5b3UgY2FuIHNlZSBpbiB0aGUgYWJv dmUuCj4gCj4gVGhlIHByb2JsZW0gaXMgdGhhdCBpZiBhbm90aGVyIGJ1cyByZWdpc3RlcnMgaXRz ZWxmIGJlZm9yZSB0aGUgU29DJ3MKPiBpMmMwIHJlZ2lzdGVycyBpdHNlbGYgYW5kIHRoYXQgYnVz IGRvZXNuJ3QgZ2l2ZSBhIG51bWJlciB0byBpdHNlbGYKPiB0aGVuIHRoZSBpMmMgc3Vic3lzdGVt IHdpbGwgY2hvc2UgIkkyQyAwIi4gIC4uLmFuZCB0aGVuIHdoZW4gdGhlIG1haW4KPiBTb0MgaTJj IGJ1cyByZWdpc3RlcnMgaXRzZWxmIGl0IHdpbGwgZmFpbCBiZWNhdXNlIGkyYzAgaXMgYWxyZWFk eQo+IHRha2VuLgo+IAo+IEJ5IGhhdmluZyBhIG9mX25vZGUgZm9yIHRoZSBoZG1pIGkyYyBidXMs IHdlIGNhbiBhc3NpZ24gYSBudW1iZXIgdG8gaXQgbGlrZToKPiAgIGkyYzE1ID0gJmhkbWk7Cj4g Cj4gVGhpcyBpcyBhbGwgZGVzY3JpYmVkIGluIHRoZSB0d28gbGlua3MgSSByZWZlcmVuY2VkIGlu IG15IG9yaWdpbmFsIHJlcGx5Lgo+IAo+IAo+IEEgcG9zc2libGUgb3RoZXIgb3B0aW9uIGlzIHRv IGhhdmUgdGhlIGkyYyBzdWJzeXN0ZW0gdHJ5IHRvIHN0YXJ0Cj4gbnVtYmVyaW5nIGF0IGEgbGFy Z2VyIGJhc2UgZm9yIGFsbCBhdXRvbWF0aWNhbGx5IG51bWJlcmVkIGJ1c3Nlcwo+ICh0aG9zZSB0 aGF0IGRpZG4ndCBzcGVjaWZ5IGEgbnVtYmVyKS4gIFRoZW4gaXQncyBtb3JlIGxpa2VseSAodGhv dWdoCj4gc3RpbGwgbm90IGd1YXJhbnRlZWQpIHRvIGNvbmZsaWN0IHdpdGggYW5vdGhlciBidXMu Li4KCkNvdWxkIHlvdSBwbGVhc2UgY2hlY2sgaWYgY29tbWl0IDAzYmRlN2MzMWEzIHNlcnZlcyB5 b3U/CgotLQpXaXRoIGJlc3Qgd2lzaGVzLApWbGFkaW1pcgpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZl bEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cDovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWls bWFuL2xpc3RpbmZvL2RyaS1kZXZlbAo=