linux-kernel - Re: [PATCH 02/10] crypto: omap-aes: Add useful debug macros

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Date:	Wed, 14 Aug 2013 22:12:45 -0500
From:	Joel Fernandes <joelf@...com>
To:	Joe Perches <joe@...ches.com>
CC:	Herbert Xu <herbert@...dor.hengli.com.au>,
	"David S. Miller" <davem@...emloft.net>,
	Mark Greer <mgreer@...malcreek.com>,
	Tony Lindgren <tony@...mide.com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Rajendra Nayak <rnayak@...com>,
	Lokesh Vutla <lokeshvutla@...com>,
	Linux OMAP List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH 02/10] crypto: omap-aes: Add useful debug macros

On 08/14/2013 07:47 PM, Joe Perches wrote:
> On Wed, 2013-08-14 at 18:40 -0500, Joel Fernandes wrote:
>> On 08/14/2013 06:29 PM, Joe Perches wrote:
>>> On Wed, 2013-08-14 at 18:12 -0500, Joel Fernandes wrote:
>>>> When DEBUG is enabled, these macros can be used to print variables
>>>> in integer and hex format, and clearly display which registers,
>>>> offsets and values are being read/written , including printing the
>>>> names of the offsets and their values.
>>> []
>>>> diff --git a/drivers/crypto/omap-aes.c b/drivers/crypto/omap-aes.c
>>> []
>>>> @@ -15,6 +15,14 @@
>>>>  
>>>>  #define pr_fmt(fmt) "%s: " fmt, __func__
>>>>  
>>>> +#ifdef DEBUG
>>>> +#define prn(num) printk(#num "=%d\n", num)
>>>> +#define prx(num) printk(#num "=%x\n", num)
>>>
>>> pr_debug?
>>
>> Sure, can change that.
>>
>>>> +#else
>>>> +#define prn(num) do { } while (0)
>>>> +#define prx(num)  do { } while (0)
>>>> +#endif
>>> []
>>>> @@ -172,13 +180,35 @@ struct omap_aes_dev {
>>>>  static LIST_HEAD(dev_list);
>>>>  static DEFINE_SPINLOCK(list_lock);
>>>>  
>>>> +#ifdef DEBUG
>>>> +#define omap_aes_read(dd, offset)					\
>>>> +	do {								\
>>>> +		omap_aes_read_1(dd, offset);				\
>>>> +		pr_debug("omap_aes_read(" #offset ")\n");		\
>>>> +	} while (0)
>>>> +
>>>> +static inline u32 omap_aes_read_1(struct omap_aes_dev *dd, u32 offset)
>>>> +#else
>>>>  static inline u32 omap_aes_read(struct omap_aes_dev *dd, u32 offset)
>>>> +#endif
>>>>  {
>>>>  	return __raw_readl(dd->io_base + offset);
>>>>  }
>>>>  
>>>> +#ifdef DEBUG
>>>> +#define omap_aes_write(dd, offset, value)				\
>>>> +	do {								\
>>>> +		pr_debug("omap_aes_write(" #offset "=%x) value=%d\n",	\
>>>> +			 offset, value);				\
>>>> +		omap_aes_write_1(dd, offset, value);			\
>>>> +	} while (0)
>>>> +
>>>> +static inline void omap_aes_write_1(struct omap_aes_dev *dd, u32 offset,
>>>> +				  u32 value)
>>>> +#else
>>>>  static inline void omap_aes_write(struct omap_aes_dev *dd, u32 offset,
>>>>  				  u32 value)
>>>> +#endif
>>>>  {
>>>>  	__raw_writel(value, dd->io_base + offset);
>>>>  }
>>>
>>> Umm, yuck?
>>>
>>> Is there any real value in read_1 and write_1?
>>
>> Can you be more descriptive? There is a lot of value in them for debug
>> to show clearly sequence of read/writes. Moreover, they are no-op'd when
>> DEBUG is disabled.
> 
> pr_debug is no-op'd when DEBUG is not #defined.
> so just use a single
> 
> omap_aes_write(...)
> {
> 	pr_debug(...)
> 	__raw_writel(...);
> }

Actually this doesn't work, as the pr_debug cannot print the name of the
offset as my original patch set does using "#offset".

There are many places where named offsets are used to pass to
read/write, and this macro helps to visually see which offset is being
written to by name.

So the original patch would stand in its current form except for a small
rewrite of the write debug part of it as follows to be cleaner getting
rid of the _1. For the read , we still need it as we need to return the
value from a function which cannot be done in a macro.

So the new patch would look something like this:

#ifdef DEBUG
#define omap_aes_read(dd, offset)                                      \
                omap_aes_read_1(dd, offset);                           \
                pr_debug("omap_aes_read(" #offset ")\n");
static inline u32 omap_aes_read_1(struct omap_aes_dev *dd, u32 offset)
#else
static inline u32 omap_aes_read(struct omap_aes_dev *dd, u32 offset)
#endif
{
        return __raw_readl(dd->io_base + offset);
}

#ifdef DEBUG
#define omap_aes_write(dd, offset, value)                              \
        do {                                                           \
                pr_debug("omap_aes_write(" #offset "=%x) value=%d\n",  \
                         offset, value);                               \
                __raw_writel(value, dd->io_base + offset);             \
        } while (0)
#else
static inline void omap_aes_write(struct omap_aes_dev *dd, u32 offset,
                                  u32 value)
{
        __raw_writel(value, dd->io_base + offset);
}
#endif



Thanks,

-Joel
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