From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v1 3/7] mfd: add atmel-lcdc driver Date: Fri, 24 Aug 2018 11:58:14 +0100 Message-ID: <20180824105814.GG28860@dell> References: <20180812184152.GA22343@ravnborg.org> <20180812184629.3808-3-sam@ravnborg.org> <20180815052435.GA6412@dell> <20180824101533.7728195a@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20180824101533.7728195a@bbrezillon> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Boris Brezillon Cc: Mark Rutland , devicetree@vger.kernel.org, Alexandre Belloni , linux-pwm@vger.kernel.org, Boris Brezillon , Nicolas Ferre , dri-devel@lists.freedesktop.org, Rob Herring , Sam Ravnborg , linux-arm-kernel@lists.infradead.org List-Id: linux-pwm@vger.kernel.org T24gRnJpLCAyNCBBdWcgMjAxOCwgQm9yaXMgQnJlemlsbG9uIHdyb3RlOgoKPiBIaSBMZWUsCj4g Cj4gT24gV2VkLCAxNSBBdWcgMjAxOCAwNjoyNDozNSArMDEwMAo+IExlZSBKb25lcyA8bGVlLmpv bmVzQGxpbmFyby5vcmc+IHdyb3RlOgo+IAo+ID4gPiArc3RhdGljIGNvbnN0IHN0cnVjdCBtZmRf Y2VsbCBsY2RjX2NlbGxzW10gPSB7Cj4gPiA+ICsJewo+ID4gPiArCQkubmFtZSA9ICJhdG1lbC1s Y2RjLXB3bSIsCj4gPiA+ICsJCS5vZl9jb21wYXRpYmxlID0gImF0bWVsLGxjZGMtcHdtIiwKPiA+ ID4gKwl9LAo+ID4gPiArCXsKPiA+ID4gKwkJLm5hbWUgPSAiYXRtZWwtbGNkYy1kYyIsCj4gPiA+ ICsJCS5vZl9jb21wYXRpYmxlID0gImF0bWVsLGxjZGMtZGlzcGxheS1jb250cm9sbGVyIiwKPiA+ ID4gKwl9LAo+ID4gPiArfTsgIAo+ID4gCj4gPiBXaWxsIHlvdSBiZSBhZGRpbmcgYW55IG1vcmUg ZGV2aWNlcywgb3IgaXMgdGhpcyB0aGUgZW50aXJldHkgb2YgdGhlCj4gPiBkZXZpY2U/ICBJZiB0 aGUgbGF0dGVyLCBJIHN1Z2dlc3QgdGhhdCB0aGlzIGRvZXNuJ3Qgd2FycmFudCBiZWluZyBhbgo+ ID4gTUZELgo+ID4gCj4gCj4gSXMgdGhlcmUgYSBsb3dlciBsaW1pdCB0byBkZWZpbmUgd2hlbiBh biBNRkQgaXMgcmVjb21tZW5kZWQsIG9yIGlzIGl0Cj4gdGhhdCB5b3UgZmluZCBhIFBXTSAoZHJp dmluZyBhIGJhY2tsaWdodCkgYW5kIGEgZGlzcGxheSBjb250cm9sbGVyCj4gY2xvc2UgZW5vdWdo IHRvIGJlIGltcGxlbWVudGVkIGluIGEgc2luZ2xlIGRyaXZlcj8KCkkgd2FzIGVycmluZyB0b3dh cmRzIHRoYXQgbGF0dGVyLgoKPiBJIHBlcnNvbmFsbHkgcHJlZmVyIHRoZSBzZXBhcmF0aW9uIHdl IGhhdmUgdG9kYXksIGJlY2F1c2UgSSBjYW4gdGhlbgo+IHBsYWNlIHRoZSBkcml2ZXJzIHdoZXJl IHRoZXkgYmVsb25nIChQV00gc3Vic3lzdGVtIGFuZCBEUk0gc3Vic3lzdGVtKQo+IGFuZCB0aGUg cmVzcGVjdGl2ZSBtYWludGFpbmVycyBrbm93IGFib3V0IHRoZXNlIGRyaXZlcnMuCgpZZXMgc2Vw YXJhdGlvbiBpcyBnb29kIGEgZ29vZCB0aGluZy4gIE5vdCBwbGFjaW5nIHRoZW0gaW4gTUZEIGFu ZApoYXZpbmcgdGhlIGluZGl2aWR1YWwgcGFydHMgcmVzaWRlIGluIHRoZSBhcHByb3ByaWF0ZSBz dWJzeXN0ZW1zIGFyZQpub3QgbXV0dWFsbHkgZXhjbHVzaXZlIHRob3VnaC4gIEkgYXNzdW1lIHRo ZSBEaXNwbGF5IENvbnRyb2xsZXIgaXMKaGlnaGVyIHJhbmtpbmcgdGhhbiB0aGUgUFdNIGRldmlj ZSByaWdodD8gIFNlZWluZyBhcyB0aGV5IGFyZSBzbwpjbG9zZWx5IGJvdW5kIGkuZS4gdGhlIERD IGNhbid0IG9wZXJhdGVkIHdpdGggdGhlIFBXTSwgaXQgd291bGQgYmUKanVzdGlmaWFibGUgdG8g cmVnaXN0ZXIgdGhlIFBXTSBmcm9tIHRoZSBEQy4KCk9mIGNvdXJzZSBpZiB0aGVyZSBpcyBjb21w bGljYXRlZCBzZXQtdXAgdG8gYmUgZG9uZSwgbG90cyBvZiBkZXZpY2VzCmFyZSBpbnZvbHZlZCBv ciB0aGVyZSBhcmUgc2hhcmVkIGZ1bmN0aW9ucyBiZXR3ZWVuIHRoZW0sIHRoZW4gdGhhdCBpcwp3 aGVyZSBNRkQgdXN1YWxseSBzdGVwcyBpbi4KCkhvd2V2ZXIsIHNpbmNlIHRoZXJlIGlzIGEgdmVy eSBzaW1pbGFyIGRldmljZSBhbHJlYWR5IGluIE1GRCwgSQpzdWdnZXN0IHlvdSBzaW1wbHkgZXh0 ZW5kIGl0IHRvIGFkZCBzdXBwb3J0IGZvciB0aGlzIG5ldyBkZXZpY2UgYW5kCmhhdmUgZG9uZS4K IAotLSAKTGVlIEpvbmVzIFvmnY7nkLzmlq9dCkxpbmFybyBTZXJ2aWNlcyBUZWNobmljYWwgTGVh ZApMaW5hcm8ub3JnIOKUgiBPcGVuIHNvdXJjZSBzb2Z0d2FyZSBmb3IgQVJNIFNvQ3MKRm9sbG93 IExpbmFybzogRmFjZWJvb2sgfCBUd2l0dGVyIHwgQmxvZwpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZl bEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFp bG1hbi9saXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 From: lee.jones@linaro.org (Lee Jones) Date: Fri, 24 Aug 2018 11:58:14 +0100 Subject: [PATCH v1 3/7] mfd: add atmel-lcdc driver In-Reply-To: <20180824101533.7728195a@bbrezillon> References: <20180812184152.GA22343@ravnborg.org> <20180812184629.3808-3-sam@ravnborg.org> <20180815052435.GA6412@dell> <20180824101533.7728195a@bbrezillon> Message-ID: <20180824105814.GG28860@dell> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 24 Aug 2018, Boris Brezillon wrote: > Hi Lee, > > On Wed, 15 Aug 2018 06:24:35 +0100 > Lee Jones wrote: > > > > +static const struct mfd_cell lcdc_cells[] = { > > > + { > > > + .name = "atmel-lcdc-pwm", > > > + .of_compatible = "atmel,lcdc-pwm", > > > + }, > > > + { > > > + .name = "atmel-lcdc-dc", > > > + .of_compatible = "atmel,lcdc-display-controller", > > > + }, > > > +}; > > > > Will you be adding any more devices, or is this the entirety of the > > device? If the latter, I suggest that this doesn't warrant being an > > MFD. > > > > Is there a lower limit to define when an MFD is recommended, or is it > that you find a PWM (driving a backlight) and a display controller > close enough to be implemented in a single driver? I was erring towards that latter. > I personally prefer the separation we have today, because I can then > place the drivers where they belong (PWM subsystem and DRM subsystem) > and the respective maintainers know about these drivers. Yes separation is good a good thing. Not placing them in MFD and having the individual parts reside in the appropriate subsystems are not mutually exclusive though. I assume the Display Controller is higher ranking than the PWM device right? Seeing as they are so closely bound i.e. the DC can't operated with the PWM, it would be justifiable to register the PWM from the DC. Of course if there is complicated set-up to be done, lots of devices are involved or there are shared functions between them, then that is where MFD usually steps in. However, since there is a very similar device already in MFD, I suggest you simply extend it to add support for this new device and have done. -- Lee Jones [???] Linaro Services Technical Lead Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog