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Subject: Re: [PATCH v2] mtd: parsers: bcm63xx: simplify CFE detection
From:   =?utf-8?Q?=C3=81lvaro_Fern=C3=A1ndez_Rojas?= <noltari@gmail.com>
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Date:   Fri, 12 Jun 2020 09:30:27 +0200
Cc:     Florian Fainelli <f.fainelli@gmail.com>, tsbogend@alpha.franken.de,
        bcm-kernel-feedback-list@broadcom.com, richard@nod.at,
        vigneshr@ti.com, Jonas Gorski <jonas.gorski@gmail.com>,
        linus.walleij@linaro.org, linux-mips@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
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To:     Miquel Raynal <miquel.raynal@bootlin.com>
Sender: linux-kernel-owner@vger.kernel.org
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Hi Miqu=C3=A8l,

> El 12 jun 2020, a las 9:02, Miquel Raynal <miquel.raynal@bootlin.com> =
escribi=C3=B3:
>=20
> Hi =C3=81lvaro,
>=20
> =C3=81lvaro Fern=C3=A1ndez Rojas <noltari@gmail.com> wrote on Thu, 11 =
Jun 2020
> 18:14:20 +0200:
>=20
>> Hi Florian,
>>=20
>>> El 11 jun 2020, a las 17:42, Florian Fainelli <f.fainelli@gmail.com> =
escribi=C3=B3:
>>>=20
>>>=20
>>>=20
>>> On 6/11/2020 8:16 AM, =C3=81lvaro Fern=C3=A1ndez Rojas wrote: =20
>>>> Hi Miquel,
>>>>=20
>>>>> El 11 jun 2020, a las 9:55, Miquel Raynal =
<miquel.raynal@bootlin.com> escribi=C3=B3:
>>>>>=20
>>>>> Hi =C3=81lvaro,
>>>>>=20
>>>>> =C3=81lvaro Fern=C3=A1ndez Rojas <noltari@gmail.com> wrote on Mon, =
 8 Jun 2020
>>>>> 18:06:49 +0200:
>>>>>=20
>>>>>> Instead of trying to parse CFE version string, which is =
customized by some
>>>>>> vendors, let's just check that "CFE1" was passed on argument 3.
>>>>>>=20
>>>>>> Signed-off-by: =C3=81lvaro Fern=C3=A1ndez Rojas =
<noltari@gmail.com>
>>>>>> Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
>>>>>> ---
>>>>>> v2: use CFE_EPTSEAL definition and avoid using an additional =
funtion.
>>>>>>=20
>>>>>> drivers/mtd/parsers/bcm63xxpart.c | 29 =
++++-------------------------
>>>>>> 1 file changed, 4 insertions(+), 25 deletions(-)
>>>>>>=20
>>>>>> diff --git a/drivers/mtd/parsers/bcm63xxpart.c =
b/drivers/mtd/parsers/bcm63xxpart.c
>>>>>> index 78f90c6c18fd..493a75b2f266 100644
>>>>>> --- a/drivers/mtd/parsers/bcm63xxpart.c
>>>>>> +++ b/drivers/mtd/parsers/bcm63xxpart.c
>>>>>> @@ -22,6 +22,9 @@
>>>>>> #include <linux/mtd/partitions.h>
>>>>>> #include <linux/of.h>
>>>>>>=20
>>>>>> +#include <asm/bootinfo.h>
>>>>>> +#include <asm/fw/cfe/cfe_api.h> =20
>>>>>=20
>>>>> Are you sure both includes are needed? =20
>>>>=20
>>>> asm/bootinfo.h is needed for fw_arg3 and asm/fw/cfe/cfe_api.h is =
needed for CFE_EPTSEAL.
>>>>=20
>>>>>=20
>>>>> I don't think it is a good habit to include asm/ headers, are you =
sure
>>>>> there is not another header doing it just fine? =20
>>>>=20
>>>> Both are needed unless you want to add another definition of =
CFE_EPTSEAL value.
>>>> There are currently two CFE magic definitions, the one in =
asm/fw/cfe/cfe_api.h and another one in bcm47xxpart.c:
>>>> =
https://github.com/torvalds/linux/blob/master/arch/mips/include/asm/fw/cfe=
/cfe_api.h#L28
>>>> =
https://github.com/torvalds/linux/blob/master/drivers/mtd/parsers/bcm47xxp=
art.c#L33 =20
>>>=20
>>> The caveat with that approach is that this reduces the compilation
>>> surface to MIPS and BMIPS_GENERIC and BCM63XX only, which is a bit
>>> small. If we could move the CFE definitions to a shared header, and
>>> consolidate the value used by bcm47xxpart.c as well, that would =
allow us
>>> to build the bcm63xxpart.c file with COMPILE_TEST on other
>>> architectures. This does not really have functional value, but for
>>> maintainers like Miquel, it allows them to quickly test their entire
>>> drivers/mtd/ directory. =20
>>=20
>> I don=E2=80=99t think fw_arg3 available on non mips archs, is it?
>> I=E2=80=99m happy to move it to a shared header (which would be a =
good location for this?), but if I=E2=80=99m right it would still be =
restricted to MIPS.
>=20
> Restricting a definition to MIPS, even if it makes sense for you is
> very limiting for me. I need to be able to build as much drivers as I
> can from my laptop and verify they at least compile correctly. If I =
need
> a MIPS toolchain, an ARC toolchain, a PowerPC, an ARM, an ARM64 and
> whatever other funky toolchain to do just that in X steps: it's very
> painful. We have been adding COMPILE_TEST dependencies on as much
> drivers as we could and we want to continue moving forward. Using such
> include would need to drop the COMPILE_TEST condition from Kconfig and
> this is not something I am willing to do.

I totally understand and agree with your point, but I still think that =
there could be a solution which would be valid for both of us.

>=20
> Thanks for your understanding :)

The current way of detecting CFE isn=E2=80=99t the proper one.
Thank you for understanding that too.

> Miqu=C3=A8l

Best regards,
=C3=81lvaro.