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Message-ID: <20230511141114.04cbd9f1@xps-13>
Date: Thu, 11 May 2023 14:11:14 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Arseniy Krasnov <avkrasnov@...rdevices.ru>
Cc: Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
Liang Yang <liang.yang@...ogic.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Kevin Hilman <khilman@...libre.com>,
Jerome Brunet <jbrunet@...libre.com>,
Jianxin Pan <jianxin.pan@...ogic.com>,
Yixun Lan <yixun.lan@...ogic.com>, <oxffffaa@...il.com>,
<kernel@...rdevices.ru>, <linux-mtd@...ts.infradead.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-amlogic@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 6/6] mtd: rawnand: meson: rename node for chip select
Hi Arseniy,
avkrasnov@...rdevices.ru wrote on Thu, 11 May 2023 13:16:59 +0300:
> On 11.05.2023 12:17, Arseniy Krasnov wrote:
> >
> >
> > On 11.05.2023 12:12, Miquel Raynal wrote:
> >> Hi Arseniy,
> >>
> >> avkrasnov@...rdevices.ru wrote on Thu, 11 May 2023 11:59:07 +0300:
> >>
> >>> On 10.05.2023 23:53, Miquel Raynal wrote:
> >>>
> >>> Hello Martin, Miquel
> >>>
> >>>> Hi Martin & Arseniy,
> >>>>
> >>>> martin.blumenstingl@...glemail.com wrote on Wed, 10 May 2023 22:40:37
> >>>> +0200:
> >>>>
> >>>>> Hello Arseniy,
> >>>>>
> >>>>> On Wed, May 10, 2023 at 1:13 PM Arseniy Krasnov
> >>>>> <AVKrasnov@...rdevices.ru> wrote:
> >>>>>>
> >>>>>> This renames node with values for chip select from "reg" to "cs". It is
> >>>>>> needed because when OTP access is enabled on the attached storage, MTD
> >>>>>> subsystem registers this storage in the NVMEM subsystem. NVMEM in turn
> >>>>>> tries to use "reg" node in its own manner, supposes that it has another
> >>>>>> layout. All of this leads to device initialization failure.
> >>>>> In general: if we change the device-tree interface (in this case:
> >>>>> replacing a "reg" with a "cs" property) the dt-bindings have to be
> >>>>> updated as well.
> >>>>
> >>>> True, and I would add, bindings should not be broken.
> >>>
> >>> I see, that's true. That is bad way to change bindings.
> >>>
> >>>>
> >>>>> Documentation/devicetree/bindings/mtd/nand-controller.yaml and
> >>>>> Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml show
> >>>>> that the chip select of a NAND chip is specified with a "reg"
> >>>>> property.
> >>>>
> >>>> All NAND controller binding expect the chip-select to be in the
> >>>> 'reg' property, very much like a spi device would use reg to store the
> >>>> cs as well: the reg property tells you how you address the device.
> >>>>
> >>>> I also fully agree with Martin's comments below. Changing reg is likely
> >>>> a wrong approach :)
> >>>>
> >>>>> Also the code has to be backwards compatible with old .dtbs.
> >>>>>
> >>>>>> Example:
> >>>>>>
> >>>>>> [...] nvmem mtd0-user-otp: nvmem: invalid reg on /soc/bus@...00000/...
> >>>>>> [...] mtd mtd0: Failed to register OTP NVMEM device
> >>>>>> [...] meson-nand ffe07800.nfc: failed to register MTD device: -22
> >>>>>> [...] meson-nand ffe07800.nfc: failed to init NAND chips
> >>>>>> [...] meson-nand: probe of ffe07800.nfc failed with error -22
> >>>>> This is odd - can you please share your definition of the &nfc node?
> >>>
> >>> Sure, here it is:
> >>>
> >>> mtd_nand: nfc@...0 {
> >>> compatible = "amlogic,meson-axg-nfc";
> >>> ...
> >>> nand@0 {
> >>> reg = <0>;
> >>> };
> >>> }
> >>>
> >>> I checked, that 'nand_set_flash_node()' is called with 'nand@0' and i suppose
> >>> that it is correct (as You mentioned below). But, 'nvmem_add_cells_from_of()' is called
> >>> with parent: 'nfc@...0', then it iterates over its childs, e.g. 'nand@0' and thus i get such
> >>> situation. I guess, that 'nvmem_add_cells_from_of()' must be called with 'nand@0' ?
> >>
> >> We recently had issues with nvmem parsing, but I believe a mainline
> >> kernel should now be perfectly working on this regard. What version of
> >> the Linux kernel are you using?
> >
> > My current version is:
> >
> > VERSION = 6
> > PATCHLEVEL = 2
> > SUBLEVEL = 0
> > EXTRAVERSION = -rc8
> >
> > Fix was in drivers/nvmem/* ?
> >
> > Thanks, Arseniy
>
> Upd: I resolved problem in the following way:
>
> nand@0 {
> reg = <0>;//chip select
>
partitions {
compatible = ...
> otp@0 {
> #address-cells = <2>;
> #size-cells = <0>;
#address/size-cells is not needed here
> compatible = "user-otp";
> reg = <A B>;
> };
> otp@1 {
> #address-cells = <2>;
> #size-cells = <0>;
Ditto
> compatible = "factory-otp";
> reg = <C D>;
> };
};
> };
>
> Now nvmem subsystem parses 'otp@0' and 'otp@1' and error is gone. 'compatible' values are
> the same as in drivers/mtd/mtdcore.c:mtd_otp_nvmem_add(). 'reg' in 'nand@0' is used as
> chip select as supposed.
I don't fully get it. The parsing on the nvmem side should not fail if
there is no subpartition/otp-region defined. Can you confirm an empty
NAND device node works? Because your last e-mail suggested the opposite.
>
> I think, this patch should be abandoned in the next version.
>
> Thanks, Arseniy
>
> >
> >>
> >> Thanks,
> >> Miquèl
Thanks,
Miquèl
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