linux-kernel - Re: [PATCH] mtd: rawnand: omap2: Actually prevent invalid configuration and build error

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Message-ID: <6c09de15-1ab2-5ca8-7003-69ff3f7c4dc5@kernel.org>
Date:   Sat, 5 Mar 2022 00:50:14 +0200
From:   Roger Quadros <rogerq@...nel.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Randy Dunlap <rdunlap@...radead.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        krzysztof.kozlowski@...onical.com, vigneshr@...com, nm@...com,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: rawnand: omap2: Actually prevent invalid
 configuration and build error

Hi Miquel,

On 04/03/2022 17:54, Miquel Raynal wrote:
> Hi Guenter, Roger,
> 
> rdunlap@...radead.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@...nel.org>  
>>>
>>> Tested-by: Guenter Roeck <linux@...ck-us.net>  
>>
>> Tested-by: Randy Dunlap <rdunlap@...radead.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.

> 
> In fact, Roger once said:
> 
> 	"We will figure out how to enable OMAP_GPMC for K3 architecture
> 	some other way."
> 
> It turns out this is not what was finally proposed. Could we try yet
> another solution?

This issue is still present i.e. we cannot enable MTD_NAND_OMAP2 driver on
K3 platform since OMAP_GPMC config is hidden and not select-able
by user or defconfig file.

But it is not yet a deal breaker since NAND on K3 is not yet enabled upstream.

For this I think OMAP_GPMC has to be a visible config entry and select-able
from a defconfig file as I had done initially [1].

Now we have a lot of explanation to write as to why we need to do it ;)

[1] - https://lore.kernel.org/lkml/20211123102607.13002-3-rogerq@kernel.org/

> 
>>
>> Thanks.
>>
>>>   
>>>> ---
>>>>  drivers/mtd/nand/raw/Kconfig | 3 +--
>>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
>>>> index 36e697456ec4..9b078e78f3fa 100644
>>>> --- 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
>>>> -	select MEMORY
>>>> -	select OMAP_GPMC
>>>> +	depends on OMAP_GPMC
>>>>  	help
>>>>  	  Support for NAND flash on Texas Instruments OMAP2, OMAP3, OMAP4
>>>>  	  and Keystone platforms.
>>>> -- 
>>>> 2.17.1
>>>>  
>>
> 
> Thanks,
> Miquèl


cheers,
-roger