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Message-ID: <59d2c9d1-dc68-2427-5ff4-ca22bc51d5b3@sberdevices.ru>
Date: Sat, 13 May 2023 16:22:41 +0300
From: Arseniy Krasnov <avkrasnov@...rdevices.ru>
To: Miquel Raynal <miquel.raynal@...tlin.com>
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>, Michael Walle <michael@...le.cc>,
Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH v3 6/6] mtd: rawnand: meson: rename node for chip select
On 12.05.2023 17:49, Miquel Raynal wrote:
> Hi Arseniy,
>
> I'm adding Rafał & Michael: any idea what could be wrong? The behavior
> below does not look expected at all, but I thought we (= Rafał, mainly)
> already sorted this out?
>
Hi Miquel, thanks for help!
just to clarify an expected behaviour: if i have the following layout in the device tree
mtd_nand: nfc@...0 {
compatible = "amlogic,meson-axg-nfc";
...
nand@0 {
reg = <0>;
};
}
node used by 'nvmem_add_cells_from_of()' must be NULL? or 'nand@0'?
I guess, that in above dts I have node 'nfc@...0' in use, because 'mtd_otp_nvmem_register()' uses
the following device before passing 'config' to 'nvmem_register()':
/* OTP nvmem will be registered on the physical device */
config.dev = mtd->dev.parent;
'mtd->dev.parent' is 'nfc@...0'.
May be 'mtd_otp_nvmem_register()' must initialize 'no_of_node' field of 'config' like in 'mtd_nvmem_add()' ?
This field is documented as:
* @no_of_node: Device should not use the parent's of_node even if it's !NULL.
In this case node passed to 'nvmem_add_cells_from_of()' will be NULL.
Thanks, 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.
>>
>> Ok, so i'll describe what happens in my case. Let's NAND node be like this (IIUC this is
>> considered as empty NAND device):
>>
>> mtd_nand: nfc@...0 {
>> compatible = "amlogic,meson-axg-nfc";
>> ...
>> nand@0 {
>> reg = <0>;
>> };
>> }
>>
>> I see, that
>>
>> 1) 'mtd_otp_nvmem_add()' calls 'mtd_otp_nvmem_register()' twice for two types of
>> OTP memory "user-otp" and "factory-otp". Let's take a look only on "user-otp".
>> 2) 'mtd_otp_nvmem_register()' tries to lookup for node in 'nand@0' which is compatible with
>> "user-otp" and then passes found (or not found, e.g. NULL) node to 'nvmem_register()'.
>> 3) 'nvmem_register()' uses this node iterating over its childs and searching value "reg" in
>> each child. If "user-otp" node is not found in 2), 'nvmem_register()' uses node 'nfc@...0'
>> also looking for "reg" value in each of its child. In this case it found "reg" in 'nand@0'
>> and fails.
>>
>> Now, if i add "compatible = "user-otp";" to 'nand@0', in step 2) search will be successful,
>> and "reg" value will be used from this new node (or we remove "reg" from it - nothing happens
>> as You wrote). So, problem is that nvmem tries to parse node with invalid "reg" value.
>>
>> Also I see, that 'nvmem_register()' is called earlier in 'mtd_nvmem_add()', but with no effect.
>> I think, that it is not related with enabled OTP feature.
>>
>> Thanks, Arseniy
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