linux-kernel - Re: [PATCH v4 5/6] ARM: zynq: Add OCM controller driver

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Message-ID: <547C7A24.8090403@monstr.eu>
Date:	Mon, 01 Dec 2014 15:24:36 +0100
From:	Michal Simek <monstr@...str.eu>
To:	Linus Walleij <linus.walleij@...aro.org>,
	Michal Simek <michal.simek@...inx.com>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Soren Brinkmann <soren.brinkmann@...inx.com>,
	Olof Johansson <olof@...om.net>, Arnd Bergmann <arnd@...db.de>,
	Josh Cartwright <josh.cartwright@...com>,
	Steffen Trumtrar <s.trumtrar@...gutronix.de>,
	Rob Herring <robherring2@...il.com>,
	Peter Crosthwaite <peter.crosthwaite@...inx.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Joe Perches <joe@...ches.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Antti Palosaari <crope@....fi>,
	Jingoo Han <jg1.han@...sung.com>,
	Sandeep Nair <sandeep_n@...com>,
	Santosh Shilimkar <santosh.shilimkar@...il.com>,
	Andy Gross <agross@...eaurora.org>,
	Thierry Reding <treding@...dia.com>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 5/6] ARM: zynq: Add OCM controller driver

On 11/28/2014 04:35 PM, Linus Walleij wrote:
> On Thu, Nov 27, 2014 at 2:57 PM, Michal Simek <michal.simek@...inx.com> wrote:
>> On 11/27/2014 02:20 PM, Linus Walleij wrote:
>>> On Fri, Nov 14, 2014 at 11:52 AM, Michal Simek <michal.simek@...inx.com> wrote:
> 
>>> (...)
>>>> +       zynq_ocmc->pool = devm_gen_pool_create(&pdev->dev,
>>>> +                                              ilog2(ZYNQ_OCMC_GRANULARITY),
>>>> +                                              -1);
>>>
>>> Do this:
>>>
>>> #include <linux/sizes.h>
>>>
>>> zynq_ocmc->pool = devm_gen_pool_create(&pdev->dev,
>>>                                        ilog2(SZ_64K),
>>>                                        -1);
>>>
>>> And get rid of the #define for ZYNQ_OCMC_GRANULARITY
>>
>> ilog2 from 32 is different to ilog2 from ilog2 from 0x10000.
> 
> Bah I misread the code, forget this comment.
> 
> Maybe it's more like I wanted
> 
> +#define ZYNQ_OCMC_BLOCK_SIZE   0x10000
> 
> To be replaced with SZ_64K
> 
> But it's a petty detail anyway.

I have fixed it.

>> Do you have any opinion regarding calling zynq_slcr_get_ocm_config()?
>>
>> Is it better to expose slcr this interface to drivers?
>> Or use regmap and read this value directly?
> 
> Depends on what provides that call. The pattern I usually follow
> is to expose the mixed-registers range as a syscon device
> using drivers/mfd/syscon.c and then use one of the methods from
> <linux/mfd/syscon.h> to look up a reference to the regmap and
> use it to access misc registers.

I have tried it and I can just use it without any problem.
I have sent v5 with origin version but in cover letter there
is a code for that.


>> Also I do read for CONFIG_SMP case jump trampoline size - maybe
>> you can have better idea how this can be done.
> 
> No I have no clue about that... :(

ok - fair enough. One option is to keep it as is. The second
option is to allocate any hardcoded size or size passed via DT.
But run-time detection is the best IMHO.

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform



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