From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90394423EA2; Wed, 7 Oct 2026 07:44:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791359060; cv=none; b=XgyK7bxwRBbgRtFU4xHCoutrU8r89DxXY6Rd6pyxH1DuTZuIUAa7AUYUK1miSnZCaqMIIpI8VNTHGshOoTqlcvK8DR1PCInD09uYE2l5G1qRh5T1w1m3CjSfULgFBtVZp9PJCvmOTIUYY2D7ioEge8dQlVtZPpqTAKcs9kT2I28= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791359060; c=relaxed/simple; bh=dwCH8kSCiVDDas4o17xef68hFnP5dWpaR5Rt9w/MO5Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J9g0Au31h2ak/mlJIYo2QAWOChNIdUS1szDqxGjVc8E+DueN6SwwlSfAc5Hal7E9rrDpM3X0QoTRCZ1YO4uLtE3hJS1C7hQNYRNAPrImNqfD5bM6vfjSYGV7SGLQkTW+GqAcyYZdyVlHlOzqd9DdGVcd22ny7jTyVlHmVmDY0Xg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=V1nco5hz; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="V1nco5hz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E78D51F0089C; Wed, 7 Oct 2026 07:44:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791359051; bh=jT2zf9su+V2G9GQXB3y4tFuNVD9WDBdAXweFNBBIfQ4=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=V1nco5hzrKpmdyxWlo78fqQDnQdFOcKLGh3v/x1fb/R9gMtxn/jWl84KV+iPj9S8d 34tD8XwWEOLrsTRuR5yzkSvYkzhDh1mlfWnoMIYtmcQUx5dJG4IkTyoVjF/zyrs9mU 0JL7kEU7bPc5M8Yzvg8SQmG27ZndbWL0cqdrQILcghZWFVIwkVfKcZSms0IoMeKmru TGZRRyW7heB3FEcJm+l5bxF1hoahss0GV2QXOLEZZ2QODk6Ea44kd3h6MCuwMDKRg8 vZhIwzyDhNDPYiTr3/lmavwZJZ4nvDaQUNNG4rD4X1fdKXPSyf59k3Nc2jnVwK2Qxa m+jEyC+dk1PVQ== Date: Wed, 7 Oct 2026 09:44:04 +0200 From: Lorenzo Pieralisi To: Robin Murphy Cc: Andy Shevchenko , "Rafael J. Wysocki" , Mark Rutland , Marc Zyngier , Daniel Lezcano , Thomas Gleixner , Greg Kroah-Hartman , Danilo Krummrich , Hanjun Guo , Sudeep Holla , Wim Van Sebroeck , Guenter Roeck , Catalin Marinas , Will Deacon , Bartosz Golaszewski , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, driver-core@lists.linux.dev, linux-watchdog@vger.kernel.org Subject: Re: [PATCH RFC 02/11] ACPI: Introduce irq_get() for static fwnodes Message-ID: References: <20260925-acpi-static-table-irq-probe-defer-v1-0-2c62125d0085@kernel.org> <20260925-acpi-static-table-irq-probe-defer-v1-2-2c62125d0085@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Oct 06, 2026 at 05:19:23PM +0100, Robin Murphy wrote: > On 28/09/2026 5:15 pm, Lorenzo Pieralisi wrote: > > On Fri, Sep 25, 2026 at 01:54:26PM +0300, Andy Shevchenko wrote: > > > On Fri, Sep 25, 2026 at 12:30:07PM +0200, Lorenzo Pieralisi wrote: > > > > On Fri, Sep 25, 2026 at 12:49:54PM +0300, Andy Shevchenko wrote: > > > > > On Fri, Sep 25, 2026 at 09:48:01AM +0200, Lorenzo Pieralisi wrote: > > > > > > ... > > > > > > > > > +static int acpi_static_fwnode_read_u32_prop_index(const struct fwnode_handle *fwnode, > > > > > > + const char *propname, > > > > > > + unsigned int index, u32 *value) > > > > > > +{ > > > > > > + u32 *values; > > > > > > + int ret, count; > > > > > > + > > > > > > + count = fwnode_property_count_u32(fwnode, propname); > > > > > > + if (count < 0) > > > > > > + return count; > > > > > > + > > > > > > + if (index >= count) > > > > > > + return -ENOENT; > > > > > > + > > > > > > + values = kcalloc(count, sizeof(*values), GFP_KERNEL); > > > > > > + if (!values) > > > > > > + return -ENOMEM; > > > > > > + > > > > > > + ret = fwnode_property_read_u32_array(fwnode, propname, values, count); > > > > > > + if (!ret) > > > > > > + *value = values[index]; > > > > > > > > > > Use standard pattern, id est > > > > > > > > > > if (ret) > > > > > ... > > > > > > > > > > > + kfree(values); > > > > > > > > > > You want to use __free() > > > > > > > > > > > + return ret; > > > > > > +} > > > > > > > > > > I believe the whole approach is suboptimal, if you wish get indexed value (but why?) > > > > > > > > Why what (that's what the irq_get() interface requires ?) I agree it is > > > > suboptimal - the whole point of the series is an RFC on using properties > > > > to store GSI number/flags, then how to read them we will optimize it > I>>> when/if we agree that's the approach to be taken. > > > > > > Why to have indexed APIs. The callers usually do not want a single item from an > > > array, they want all of them or a big pile (exception is the array of strings, > > > but we have matching functions for that). > > > > > > As per approach, this patch is against device property and I don't think we are > > > going to agree on the approach taken in *this* patch. > > > > Coming back to this, what is needed here is a way to stash the GSI number, > > flags and name in stardard storage (like OF nodes IRQ properties, ACPI objects > > _CRS, etc). > > > > To give you some background, I thought about adding an array of: > > > > GSI [number, flags, name] > > > > to the ACPI static fwnode itself. Then basically the irq_get() API has got > > all the information it needs from the primary fwnode; while doing that I > > thought that this might have been a bit like reinventing software nodes > > (granted, software node properties are ways more general that what I suggest > > above and I don't expect any other property to be ever added to static fwnodes) > > that's why I put together the series as it is, precisely to understand what's > > best. > > > > When you say "against device property", what do you mean precisely ? > > > > I suppose you mean that this approach goes against software node properties > > usage guidelines ? > > > > Anyway, again, it is just to provide some context, we are talking about > > a bunch of platform devices, it is nice to have a generic solution but > > it has to be simple enough too given its scope, I understand very well > > your concern with this approach as-is - it is there to find a way > > forward together and show what the problem is. > > I guess software node properties look inviting in theory since they're a > ready-made mechanism for effectively attaching arbitrary data to a fwnode, > however looking at patches 6-7 and the amount of boilerplate involved in the > reality, I'm inclined to think that a dedicated structure for static nodes > is probably the best and most efficient compromise here. The redundancy > argument rather falls apart once we end up creating copies of those > contentiously-made-up property name strings for every node, especially given > that any one of those alone is probably already more than the amount of > actual data we need per node... > > Perhaps the "purest" option might be to just store a function pointer in the > fwnode wrapper for each static table type to provide its own internal > irq_get() callback, so not stashing intermediate GSI data at all, but I > suspect that might end up being more work overall. Thanks Robin. Yes, those are the possible options, last one requiring a look-up from fwnode to the data providing GSI numbers/flags for that specific fwnode - we do have that for IORT but I need to check for other devices. To be honest, I implemented the three of them while prototyping, it is just a matter of choosing which one we want to support to sort this out. Thanks ! Lorenzo > Cheers, > Robin. > > > > > Thanks, > > Lorenzo > > > > > > > it needs to be retrieved as that in the guts of ACPI. Allocating memory for the whole > > > > > array to retrieve a single element is simply wrong. > > > > > > ... > > > > > > > > > +#define ACPI_IRQ_PROP_GSI "linux,acpi-gsi" > > > > > > +#define ACPI_IRQ_PROP_GSI_TRIGGER "linux,acpi-gsi-trigger" > > > > > > +#define ACPI_IRQ_PROP_GSI_POLARITY "linux,acpi-gsi-polarity" > > > > > > > > > > Oh... This sounds like a big ugly hack. > > > > > > > > That does not help much I am afraid. > > > > > > > > What's a ugly hack ? Property names ? Using properties for this purpose ? > > > > > > Yes, properties started with "linux," for some core functionality. > > > Yes, using properties for this also doesn't sound right. I think the problem > > > here is in the table specifications or somewhere that deep. That's why we > > > ended up in this series. > > > > > > > Again, it is an RFC for this specific reason and I mentioned that in the > > > > cover letter, thank you for your inputs. > > > > > > And here we have a discussion started :-) > > > > > > P.S. Looks like I was too quick to jump into this thread. I will wait for > > > others to share their view on all this. > > > > > > -- > > > With Best Regards, > > > Andy Shevchenko > > > > > > >