From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v3 02/15] Driver core: Unified device properties interface for platform firmware Date: Thu, 02 Oct 2014 09:46:29 +0200 Message-ID: <6092163.dWXI6rWTCu@wuerfel> References: <1410868367-11056-1-git-send-email-mika.westerberg@linux.intel.com> <7365448.TlsV4zB2It@wuerfel> <4390403.PNxQqnBDGX@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from mout.kundenserver.de ([212.227.17.24]:65487 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751958AbaJBHqh (ORCPT ); Thu, 2 Oct 2014 03:46:37 -0400 In-Reply-To: <4390403.PNxQqnBDGX@vostro.rjw.lan> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Mika Westerberg , linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, Linus Walleij , Alexandre Courbot , Dmitry Torokhov , Bryan Wu , Lee Jones , Grant Likely , Aaron Lu , Darren Hart On Thursday 02 October 2014 00:09:44 Rafael J. Wysocki wrote: > On Wednesday, October 01, 2014 09:47:40 AM Arnd Bergmann wrote: > > On Wednesday 01 October 2014 04:10:03 Rafael J. Wysocki wrote: > > I still have my reservations against the child accessors, and would > > like to hear what other people think. Passing a void pointer rather > > than struct fw_dev_node has both advantages and disadvantages, and > > I won't complain about either one if enough other people on the DT > > side would like to see the addition of the child functions. > > I actually would rather like to know if the people on the DT side have any > problems with the child functions. Sure, any kind of feedback would be helpful really. > Because, suppose that they wouldn't like those functions at all. What are we > supposed to do, then, honestly? Add the whole DT vs ACPI logic to the leds-gpio > and gpio_keys_polled drivers? But these drivers have no reason whatsoever > to include that. Zero. > > So suggestions welcome. > > [BTW, In principle we also could use something like > > typedef union dev_node { > struct acpi_device *acpi_node; > struct device_node *of_node; > } dev_node_t; > > instead of the (void *) for more type safety. It still is useful to pass the > parent pointer along with that, though.] Yes, I'm not worried about the implementation details. > > > Finally, device_for_each_child_node() is added for iterating over > > > the children of the device description object associated with a > > > given device. > > > > > > The interface covers both ACPI and Device Trees. > > > > > > This change set includes material from Mika Westerberg and Aaron Lu. > > > > > > > Regarding device_for_each_child_node(), the syntax is inconsistent > > with what we normally use, which can probably be changed. All of the > > DT for_each_* helpers are macros that are used like > > > > struct device *dev = ...; > > void *child; /* iterator */ > > > > device_for_each_child_node(dev, child) { > > u32 something; > > device_child_property_read_u32(dev, child, "propname", &something); > > > > do_something(dev, something); > > } > > > > If we get a consensus on having the child interfaces, I'd rather see > > them done this way than with a callback pointer, for consistency > > reasons. > > That certainly is doable, although the resulting macro would generate a rather > large chunk of code each time it is used. #define device_for_each_child_node(dev, child) \ for (child = device_get_next_child_node(dev, NULL), child, \ child = device_get_next_child_node(dev, child)) void *device_get_next_child_node(struct device *dev, void *child) { if (IS_ENABLED(CONFIG_OF) && dev->of_node) return of_get_next_child(dev->of_node, child); else if (IS_ENABLED(CONFIG_ACPI) && ...) return acpi_get_next_child(dev, child); return NULL; } Not any more code than what we have today for the DT-only case, and it's really just a function call in a loop. Arnd