Re: [PATCH v6 01/11] mtd: core: always create master device

From: Richard Weinberger <richard@nod.at>
To: Guenter Roeck <linux@roeck-us.net>,
	 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 v6 01/11] mtd: core: always create master device
Date: Mon, 9 Jun 2025 23:27:09 +0200 (CEST)	[thread overview]
Message-ID: <1176847729.134356549.1749504429656.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <2e5ebbdd-2a57-4f1f-85c6-7c2dff127b50@roeck-us.net>

----- Ursprüngliche Mail -----
> Von: "Guenter Roeck" <linux@roeck-us.net>
>>> I am trying to boot from "pnor". It looks like the partition data (from
>>> devicetree)
>>> is now ignored. mtdblock6 used to be the second flash.
>>>
>>> Guenter
>> 
>> Is this with CONFIG_MTD_PARTITIONED_MASTER?
>> 
> 
> Yes
> 
>> I think that mtd_is_partition is ambiguous now.
>> We always have master partition when CONFIG_MTD_PARTITIONED_MASTER
>> is enabled and parent check is useless.
>> We must check grandparent in this case.
>> Miquel, am I right?
>> 
>> We can return to older patch version that have created partition
>> instead of the master device.
>> Or try to fix mtd_is_partition, like below.
>> Guenter, is below patch helps?
>> 
> No, it does not make a difference. Partitions are still not created.

Looks like all partition parsing is broken when CONFIG_MTD_PARTITIONED_MASTER=y is set.
Alexander, I was able to reproduce with MTDRAM and the mtdparts= kernel parameter.
Build with CONFIG_MTD_MTDRAM=y and CONFIG_MTD_PARTITIONED_MASTER=y,
pass mtdparts=\"mtdram test device:256k(foo)ro,-(bar)\" to the kernel command line.

Before your change:
$ cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 00400000 00020000 "mtdram test device"
mtd1: 00040000 00020000 "foo"
mtd2: 003c0000 00020000 "bar"

After:
$ cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00400000 00020000 "mtdram test device"

Hope this helps!

Thanks,
//richard