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

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Date:	Thu, 15 Aug 2013 09:23:18 +0300
From:	Dmitry Kasatkin <d.kasatkin@...sung.com>
To:	joelf@...com
Cc:	Joe Perches <joe@...ches.com>,
	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 15/08/13 06:12, Joel Fernandes wrote:
> 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);
> }

Bellow version "write" looks much more readable - never re-define
function signature by macro.
Above should be similar as well...

> #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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