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Date:	Sun, 2 Sep 2012 18:42:49 +0530
From:	shiraz hashim <shiraz.linux.kernel@...il.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Roland Stigge <stigge@...com.de>, aletes.xgr@...il.com,
	broonie@...nsource.wolfsonmicro.com, grant.likely@...retlab.ca,
	rob.herring@...xeda.com, rob@...dley.net,
	devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	spi-devel-general@...ts.sourceforge.net,
	gabriel.fernandez@...ricsson.com, lee.jones@...aro.org,
	viresh.kumar@...aro.org, sachin.verma@...com
Subject: Re: [PATCH v6 1/3] spi/pl022: Add chip select handling via GPIO

Hi Linus,

On Sun, Sep 2, 2012 at 12:48 PM, Linus Walleij <linus.walleij@...aro.org> wrote:
> On Sat, Sep 1, 2012 at 1:14 PM, shiraz hashim
> <shiraz.linux.kernel@...il.com> wrote:
>> Hi Roland,
>>
>> On Wed, Aug 22, 2012 at 7:19 PM, Roland Stigge <stigge@...com.de> wrote:
>>> @@ -2016,6 +2030,8 @@ pl022_probe(struct amba_device *adev, co
>>>         pl022->master_info = platform_info;
>>>         pl022->adev = adev;
>>>         pl022->vendor = id->data;
>>> +       /* Point chipselects to allocated memory beyond the main struct */
>>> +       pl022->chipselects = (int *) pl022 + sizeof(struct pl022);
>>
>> This is going beyond memory allocated for chipselects
>> as it adds 4 * sizeof(struct pl022) bytes to pl022.
>
> Yes that is why the allocation looks like this:
>
> +       master = spi_alloc_master(dev, sizeof(struct pl022) + sizeof(int) *
> +                                 platform_info->num_chipselect);
>

The allocation is such because type of chipselects is int.

The statement for allocation is correct, but

       pl022->chipselects = (int *) pl022 + sizeof(struct pl022);

is not adding  sizeof(struct pl022) bytes to pl022 base (which we want),
but infact 4 times the size of pl022 (because type of pl022 is now int *).

Do you get my point ?  This would go way beyond memory allocated
for chipselects.

-- 
regards
Shiraz Hashim
--
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