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SubjectRe: [PATCH] mtd: rawnand: omap2: Actually prevent invalid configuration and build error
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Hi Miquel,

On 07/03/2022 16:12, Miquel Raynal wrote:
> Hi Roger,
>
> rogerq@kernel.org wrote on Mon, 7 Mar 2022 14:25:48 +0200:
>
>> Hi Miquel,
>>
>> On 07/03/2022 12:03, Miquel Raynal wrote:
>>> Hi Roger,
>>>
>>> rogerq@kernel.org wrote on Sat, 5 Mar 2022 00:50:14 +0200:
>>>
>>>> Hi Miquel,
>>>>
>>>> On 04/03/2022 17:54, Miquel Raynal wrote:
>>>>> Hi Guenter, Roger,
>>>>>
>>>>> rdunlap@infradead.org wrote on Sat, 26 Feb 2022 22:55:28 -0800:
>>>>>
>>>>>> On 2/19/22 16:44, Guenter Roeck wrote:
>>>>>>> On Sat, Feb 19, 2022 at 09:36:00PM +0200, Roger Quadros wrote:
>>>>>>>> The root of the problem is that we are selecting symbols that have
>>>>>>>> dependencies. This can cause random configurations that can fail.
>>>>>>>> The cleanest solution is to avoid using select.
>>>>>>>>
>>>>>>>> This driver uses interfaces from the OMAP_GPMC driver so we have to
>>>>>>>> depend on it instead.
>>>>>>>>
>>>>>>>> Fixes: 4cd335dae3cf ("mtd: rawnand: omap2: Prevent invalid configuration and build error")
>>>>>>>> Signed-off-by: Roger Quadros <rogerq@kernel.org>
>>>>>>>
>>>>>>> Tested-by: Guenter Roeck <linux@roeck-us.net>
>>>>>>
>>>>>> Tested-by: Randy Dunlap <rdunlap@infradead.org>
>>>>>
>>>>> Sorry for noticing that just now, but there is still a problem with
>>>>> this patch: we now always compile-in the OMAP_GPMC driver whenever we
>>>>> need the NAND controller, even though it is not needed. This grows the
>>>>> kernel for no reason.
>>>>
>>>> Sorry, I did not understand what you meant.
>>>>
>>>> We no longer explicitly enable OMAP_GPMC since we dropped the "select".
>>>> This fixes all build issues that were reported recently.
>>>>
>>>> MTD_NAND_OMAP2 will not be enabled if OMAP_GPMC is not since we added
>>>> the "depends on". This fixes the original build issue that we started to
>>>> fix with select initially.
>>>
>>> Yes, this side is fine.
>>>
>>> In the initial commit, you proposed:
>>>
>>> --- a/drivers/mtd/nand/raw/Kconfig
>>> +++ b/drivers/mtd/nand/raw/Kconfig
>>> @@ -42,7 +42,8 @@ config MTD_NAND_OMAP2
>>> tristate "OMAP2, OMAP3, OMAP4 and Keystone NAND controller"
>>> depends on ARCH_OMAP2PLUS || ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
>>> depends on HAS_IOMEM
>>> + select OMAP_GPMC if ARCH_K3
>>>
>>> Which creates a dependency over OMAP_GPMC only for a single
>>> architecture. Which means that other OMAP platforms do not necessarily
>>> need OMAP_GPMC for the NAND controller to work. Now, you propose:
>>
>> No that is not true. Other platforms that need MTD_NAND_OMAP2 are
>> explicitly selecting OMAP_GPMC
>> i.e. in arch/arm/mach-omap2/Kconfig
>
> Okay, in this case the fix is fine but we will need to clean this up in
> a second time.

What clean up are you implying here? Those legacy platform might need
OMAP_GPMC for booting so they select it. There is nothing much we can do there.

What is left to do now is make user/defconfig files to enable OMAP_GPMC driver
so other platforms that don't need OMAP_GPMC for basic operation can still
enable them later via defconfig or manually by user.

>
>>> --- a/drivers/mtd/nand/raw/Kconfig
>>> +++ b/drivers/mtd/nand/raw/Kconfig
>>> @@ -42,8 +42,7 @@ config MTD_NAND_OMAP2
>>> tristate "OMAP2, OMAP3, OMAP4 and Keystone NAND controller"
>>> depends on ARCH_OMAP2PLUS || ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
>>> depends on HAS_IOMEM
>>> depends on OMAP_GPMC
>>>
>>> This means any of the other OMAP architectures will compile the GPMC
>>> driver even though they might not need it, which would unnecessarily
>>> increase the kernel size.
>>>
>>> Am I missing something?
>>
>> MTD_NAND_OMAP2 NAND controller is a submodule of the OMAP GPMC IP. So it
>> cannot work without OMAP_GPMC driver.
>
> I didn't remember exactly but in that case it's okay, I was just
> surprised by the "select GPMC if ARCH_K3" but indeed with this
> explanation it makes more sense.
>
>> Hope this clarifies the doubts.
>
> Yes, thanks. I will send the fix to Linus then.
>
> Cheers,
> Miquèl

cheers,
-roger

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