[PATCH v2] drivers/misc: (aspeed-lpc-snoop): Add ast2400 to compat

[PATCH v2] drivers/misc: (aspeed-lpc-snoop): Add ast2400 to compat

[Patrick Venture]

This driver can be used on the aspeed ast2400 with minor
modifications.

Tested: ast2400 on quanta-q71l

Signed-off-by: Patrick Venture <venture@google.com>
---
v2: added aspeed-g5 area because ast2400 doesn't use those bits.
    also updated commit message.
---
 drivers/misc/aspeed-lpc-snoop.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c
index 593905565b74..83f9a9e5a7cf 100644
--- a/drivers/misc/aspeed-lpc-snoop.c
+++ b/drivers/misc/aspeed-lpc-snoop.c
@@ -155,8 +155,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 	regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
 	regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
 			   lpc_port << snpwadr_shift);
+#ifdef CONFIG_MACH_ASPEED_G5
 	regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
-
+#endif
 	return rc;
 }
 
@@ -241,6 +242,7 @@ static int aspeed_lpc_snoop_remove(struct platform_device *pdev)
 
 static const struct of_device_id aspeed_lpc_snoop_match[] = {
 	{ .compatible = "aspeed,ast2500-lpc-snoop" },
+	{ .compatible = "aspeed,ast2400-lpc-snoop" },
 	{ },
 };
 
-- 
2.13.2.725.g09c95d1e9-goog

Re: [PATCH v2] drivers/misc: (aspeed-lpc-snoop): Add ast2400 to compat

[Arnd Bergmann]

On Wed, Jul 5, 2017 at 9:04 PM, Patrick Venture <venture@google.com> wrote:
> This driver can be used on the aspeed ast2400 with minor
> modifications.
>
> Tested: ast2400 on quanta-q71l
>
> Signed-off-by: Patrick Venture <venture@google.com>
> ---
> v2: added aspeed-g5 area because ast2400 doesn't use those bits.
>     also updated commit message.
> ---
>  drivers/misc/aspeed-lpc-snoop.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c
> index 593905565b74..83f9a9e5a7cf 100644
> --- a/drivers/misc/aspeed-lpc-snoop.c
> +++ b/drivers/misc/aspeed-lpc-snoop.c
> @@ -155,8 +155,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
>         regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
>         regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
>                            lpc_port << snpwadr_shift);
> +#ifdef CONFIG_MACH_ASPEED_G5
>         regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
> -
> +#endif
>         return rc;
>  }

Hi Patrick,

Sorry for bringing up yet another point on a fairly trivial patch, but
in general,
I'd recommend making this a runtime check rather than compile-time.

At the moment, your version is safe because CONFIG_MACH_ASPEED_G5
and CONFIG_MACH_ASPEED_G4 are mutually exclusive and there is
always one of them set, but once we get support for G6, G7 etc,
the driver might silently break when it behaves differently depending
on a configuration option that may or may not be set on a particular
kernel build.

You can use the .data field in the of_device_id to add a trigger for the
behavior change.

       Arnd

Re: [PATCH v2] drivers/misc: (aspeed-lpc-snoop): Add ast2400 to compat

[Patrick Venture]

On Wed, Jul 5, 2017 at 12:43 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Wed, Jul 5, 2017 at 9:04 PM, Patrick Venture <venture@google.com> wrote:
>> This driver can be used on the aspeed ast2400 with minor
>> modifications.
>>
>> Tested: ast2400 on quanta-q71l
>>
>> Signed-off-by: Patrick Venture <venture@google.com>
>> ---
>> v2: added aspeed-g5 area because ast2400 doesn't use those bits.
>>     also updated commit message.
>> ---
>>  drivers/misc/aspeed-lpc-snoop.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c
>> index 593905565b74..83f9a9e5a7cf 100644
>> --- a/drivers/misc/aspeed-lpc-snoop.c
>> +++ b/drivers/misc/aspeed-lpc-snoop.c
>> @@ -155,8 +155,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
>>         regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
>>         regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
>>                            lpc_port << snpwadr_shift);
>> +#ifdef CONFIG_MACH_ASPEED_G5
>>         regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
>> -
>> +#endif
>>         return rc;
>>  }
>
> Hi Patrick,
>
> Sorry for bringing up yet another point on a fairly trivial patch, but
> in general,
> I'd recommend making this a runtime check rather than compile-time.
>
> At the moment, your version is safe because CONFIG_MACH_ASPEED_G5
> and CONFIG_MACH_ASPEED_G4 are mutually exclusive and there is
> always one of them set, but once we get support for G6, G7 etc,
> the driver might silently break when it behaves differently depending
> on a configuration option that may or may not be set on a particular
> kernel build.
>
> You can use the .data field in the of_device_id to add a trigger for the
> behavior change.
>
>        Arnd

No problem whatsoever.  You're quite right.  I forgot about future
aspeed platforms.  I'm going to dig around a few drivers and see what
the right way is to handle this at run-time.  Presumably something
like:

#ifdef CONFIG_MACH_ASPEED_G4
.data = G4,
#else
.data = G5,
#endif

Since we're holding that maybe the future should default to this
behaviour.  Is it linux standard to do something like #(error) in the
#else so that it fails if they didn't update this driver instead of
defaulting to the G5 setting?

Thanks,
Patrick