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

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: "Usyskin, Alexander" <alexander.usyskin@intel.com>
Cc: "Richard Weinberger" <richard@nod.at>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"De Marchi, Lucas" <lucas.demarchi@intel.com>,
	"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
	"Vivi, Rodrigo" <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>,
	"Poosa, Karthik" <karthik.poosa@intel.com>,
	"Abliyev, Reuven" <reuven.abliyev@intel.com>,
	"Weil, Oren jer" <oren.jer.weil@intel.com>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 01/11] mtd: core: always create master device
Date: Wed, 15 Jan 2025 20:22:25 +0100	[thread overview]
Message-ID: <871px3lw5q.fsf@bootlin.com> (raw)
In-Reply-To: <CY5PR11MB63663795A6C4DC83CB89602AED182@CY5PR11MB6366.namprd11.prod.outlook.com> (Alexander Usyskin's message of "Tue, 14 Jan 2025 14:05:40 +0000")

Hi,

On 14/01/2025 at 14:05:40 GMT, "Usyskin, Alexander" <alexander.usyskin@intel.com> wrote:

>> > > Create master device without partition when
>> > > CONFIG_MTD_PARTITIONED_MASTER flag is unset.
>> >
>> > I don't think you took into consideration my remarks regarding the fact
>> > that you would break userspace. If you enable the master, you no longer
>> > have the same device numbering in userspace. I know people should not
>> > care about these numbers, but in practice they do.
>> >
>> > If I'm wrong, please be a little more verbose about why :)
>> >
>> > Thanks,
>> > Miquèl
>> 
>> Hi Miquel
>> 
>> I've created separate class (mtd_master) for such devices.
>> Uses-space looking for mtd device continues to receive same number of
>> /dev/mtdX devices.
>> There will be additional /dev/mtd_masterX devices, but this is unavoidable, I
>> suppose.
>> Maybe we can rename it to something that not in /dev/mtd* expression (e.g.
>> mastermtdX),
>> if it helps.
>> 
>
> Miquel, is this good enough or requires rewrite?

This is an important change that requires attention, and at the time I
have not been able to dedicate enough to this patch.

Also, if the other mtd maintainers want to help, I'll be enthousiastic
about it :)

Thanks,
Miquèl