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From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
To: Stefan Wahren <info-saaNCTdWVBT7BZbvpMY5sg@public.gmane.org>
Cc: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>,
	"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
	<linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
	"linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH 1/2] spi: bcm2835: add spi-bcm2835aux driver for the auxiliar spi1 and spi2
Date: Thu, 30 Jul 2015 17:27:44 +0200	[thread overview]
Message-ID: <E9EEB426-95DE-4785-949C-6A402A25E115@martin.sperl.org> (raw)
In-Reply-To: <97861F80-CF83-4FF2-B96E-CDFB1A8F4921-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>


> On 30.07.2015, at 09:10, Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> wrote:
>> What about adding “bcrm,bcm2835-aux-enable” to drivers/mfd/syscon.c
>> compatibility?
>> 
>> That way we:
>> * have a clean dt that only represents hardware
>> * reuse existing code with minimal modifications
>> * minimal effort
>> 
>> That would be a minimal patch to enable this, so we can ask if that is
>> acceptable and if it is not then we can still think of something else,
>> which would be mostly replicating the bit-management portion of syscon.
> 
> that minimal patch extending compatibility of syscon and also including
> the config portion for the kernel as well as the device tree would look
> something like this (note that it is not tested yet):

> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -211,6 +211,12 @@ static int syscon_probe(struct platform_device *pdev)
>        return 0;
> }
> 
> +static const struct of_device_id syscon_match[] = {
> +       { .compatible = "bcrm,bcm2835-aux-enable", },
> +       {}
> +};
> +MODULE_DEVICE_TABLE(of, syscon_match);
> +
> static const struct platform_device_id syscon_ids[] = {
>        { "syscon", },
>        { }

Unfortunately the above does not work with syscon, as it
_explicitly_ requires a compatibility of “syscon”:

        if (!of_device_is_compatible(np, "syscon"))
                return ERR_PTR(-EINVAL);

So by the rational of device-tree representing only the
hardware this driver should never get used because of this
limitation

Replicating syscon/regmap into a separate driver that has explicit
compatibility of “bcrm, bcm2835-aux” results in more than 162 lines
of extra code (plus changes to Makefile and Kconfig)

So I wonder if it would not be acceptable to allow:
  compatiblity = “bcrm,bcm2835-aux”, “syscon”;

and avoid an unnecessary extra driver which provides only
the following functions:

void bcm2835aux_enable(struct bcm2835aux *aux, u32 mask);
void bcm2835aux_disable(struct bcm2835aux *aux, u32 mask);
struct bcm2835aux *bcm2835aux_lookup_by_phandle(
	struct device_node *np,
	const char *property);

all of which are available almost identical in syscon/regmap.

We can also try to discuss if a modification to syscon so that it
also checks the “explicit” compatibility in the configured list.

Martin--
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  parent reply	other threads:[~2015-07-30 15:27 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-22 13:40 [PATCH 1/2] spi: bcm2835: add spi-bcm2835aux driver for the auxiliar spi1 and spi2 kernel-TqfNSX0MhmxHKSADF0wUEw
     [not found] ` <1434980408-4086-1-git-send-email-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-06-22 13:40   ` [PATCH 2/2] dt: brcm,bcm2835-aux-spi: add binding documentation for new spi-bcm2835aux kernel-TqfNSX0MhmxHKSADF0wUEw
     [not found]     ` <1434980408-4086-2-git-send-email-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-06-22 17:55       ` [PATCH 2/2] dt: brcm, bcm2835-aux-spi: " Stefan Wahren
     [not found]         ` <55884C2B.8040601-saaNCTdWVBT7BZbvpMY5sg@public.gmane.org>
2015-06-22 19:19           ` Martin Sperl
2015-06-22 14:08   ` [PATCH 1/2] spi: bcm2835: add spi-bcm2835aux driver for the auxiliar spi1 and spi2 Noralf Trønnes
2015-06-22 14:55   ` Jakub Kiciński
2015-06-22 15:26     ` Martin Sperl
     [not found]       ` <E72B3D8C-EA1B-4B4C-8EAF-C14A5631882E-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-06-25 14:19         ` Martin Sperl
     [not found]           ` <97C7561C-6D67-4F51-94BB-3B8D401D77A0-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-06-30  9:42             ` Mark Brown
     [not found]               ` <20150630094232.GM11162-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2015-07-01 19:39                 ` Martin Sperl
     [not found]                   ` <6A2CCE70-5DAF-4E86-A0A4-F5E93FD1B540-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-01 20:57                     ` Noralf Trønnes
     [not found]                       ` <55945448.7010502-L59+Z2yzLopAfugRpC6u6w@public.gmane.org>
2015-07-05  1:14                         ` Martin Sperl
     [not found]                           ` <1400E1A3-43E1-4D0E-A54D-E5D668A4C516-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-05 10:37                             ` Noralf Trønnes
     [not found]                               ` <55990904.9040002-L59+Z2yzLopAfugRpC6u6w@public.gmane.org>
2015-07-05 13:11                                 ` Martin Sperl
2015-07-11  4:41                             ` Stephen Warren
2015-07-11  4:37         ` Stephen Warren
2015-07-11  4:53   ` Stephen Warren
     [not found]     ` <55A0A150.3060809-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2015-07-12  2:10       ` Martin Sperl
     [not found]         ` <ECFBB7BF-1316-4565-B1F2-FB2651131882-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-14  4:56           ` Stephen Warren
     [not found]             ` <55A49662.3000706-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2015-07-14 12:39               ` Martin Sperl
     [not found]                 ` <2768BFA9-7FE9-4EDC-8692-AC3F070BD874-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-22  1:55                   ` Stephen Warren
     [not found]                     ` <55AEF828.20908-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2015-07-22 16:28                       ` Martin Sperl
     [not found]                         ` <0125992E-40F4-4702-8404-2943FF9A8788-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-24  4:09                           ` Stephen Warren
     [not found]                             ` <55B1BA7A.1090104-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2015-07-24  6:47                               ` Martin Sperl
     [not found]                                 ` <9005ABEC-C60A-4814-AD60-AD5BB09808F2-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-28  2:51                                   ` Stephen Warren
     [not found]                                     ` <55B6EE1A.2070605-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2015-07-28  6:18                                       ` Martin Sperl
     [not found]                                         ` <836DA157-3072-441A-A160-E1FDBB119E88-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-28 10:48                                           ` Martin Sperl
     [not found]                                             ` <55B75E07.1080104-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-29 16:37                                               ` Stefan Wahren
     [not found]                                                 ` <55B9014C.7020105-saaNCTdWVBT7BZbvpMY5sg@public.gmane.org>
2015-07-29 17:25                                                   ` Noralf Trønnes
2015-07-29 21:16                                                   ` Martin Sperl
     [not found]                                                     ` <C767C9AD-A9B5-428F-A207-D67269B380C6-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-30  5:36                                                       ` Stefan Wahren
     [not found]                                                         ` <55B9B7EF.2070108-saaNCTdWVBT7BZbvpMY5sg@public.gmane.org>
2015-07-30  6:45                                                           ` Martin Sperl
     [not found]                                                             ` <C2C16277-C6C1-4F86-BB88-580CF667EF24-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-30  7:10                                                               ` Martin Sperl
     [not found]                                                                 ` <97861F80-CF83-4FF2-B96E-CDFB1A8F4921-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-30 15:27                                                                   ` Martin Sperl [this message]
     [not found]                                                                     ` <E9EEB426-95DE-4785-949C-6A402A25E115-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2015-07-31 18:42                                                                       ` Stefan Wahren
2015-08-01  2:55                                               ` Stephen Warren
2015-08-01  2:51                                           ` Stephen Warren

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