Re: [PATCH v4 01/11] mtd: core: always create master device

From: Richard Weinberger <richard@nod.at>
To: Alexander Usyskin <alexander.usyskin@intel.com>
Cc: "Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Lucas De Marchi" <lucas.demarchi@intel.com>,
	"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"David Airlie" <airlied@gmail.com>,
	"Simona Vetter" <simona@ffwll.ch>,
	"Jani Nikula" <jani.nikula@linux.intel.com>,
	"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
	"Tvrtko Ursulin" <tursulin@ursulin.net>,
	"Karthik Poosa" <karthik.poosa@intel.com>,
	"Reuven Abliyev" <reuven.abliyev@intel.com>,
	"Oren Weil" <oren.jer.weil@intel.com>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	"DRI mailing list" <dri-devel@lists.freedesktop.org>,
	intel-gfx <intel-gfx@lists.freedesktop.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 01/11] mtd: core: always create master device
Date: Fri, 17 Jan 2025 23:27:16 +0100 (CET)	[thread overview]
Message-ID: <677101004.241399779.1737152836282.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <CY5PR11MB63660C230457299E1201C38FED1A2@CY5PR11MB6366.namprd11.prod.outlook.com>

----- Ursprüngliche Mail -----
>> > This streamlines device tree and allows to anchor
>> > runtime power management on master device in all cases.
>> 
>> Please explain in more detail why this is needed.
>> If this change makes the overall situation better and breaks
>> no userspace, I'm happy. :-)
>> 
> 
> The rest of the series is a driver that need runtime power management.
> Absence of the master device breaks power management logic,
> as kernel automatically propagates state from children to parent.
> I initially hooked runtime_pm on chip auxiliary device, but this is a hack,
> not a solution.

So, the problem is that mtd partitions don't have a common parent/master like
we have for generic disks?
Please give more details.
We have already a non-optimal situation in mtd and I want to fully understand
the requirements to get it this time right.

Thanks,
//richard