linux-kernel - Re: [PATCH] media: s5p-jpeg: change "RST" to "RSET" to fix build warnings

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Date:   Mon, 6 Sep 2021 16:51:42 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>,
        linux-media@...r.kernel.org,
        Andrzej Pietrasiewicz <andrzejtp2010@...il.com>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] media: s5p-jpeg: change "RST" to "RSET" to fix build
 warnings

On 9/5/21 11:51 PM, Mauro Carvalho Chehab wrote:
> Em Sun,  5 Sep 2021 16:57:15 -0700
> Randy Dunlap <rdunlap@...radead.org> escreveu:
> 
>> The use of a macro named 'RST' conflicts with one of the same name
>> in arch/mips/include/asm/mach-rc32434/rb.h. This causes build
>> warnings on some MIPS builds.
>>
>> Change the use of RST to the name RSET.
>>
>> Fixes these build warnings:
>>
>> In file included from ../drivers/media/platform/s5p-jpeg/jpeg-hw-exynos3250.c:14:
>> ../drivers/media/platform/s5p-jpeg/jpeg-core.h:43: warning: "RST" redefined
>>     43 | #define RST                             0xd0
>>        |
>> ../arch/mips/include/asm/mach-rc32434/rb.h:13: note: this is the location of the previous definition
>>     13 | #define RST             (1 << 15)
>>
>> In file included from ../drivers/media/platform/s5p-jpeg/jpeg-hw-s5p.c:13:
>> ../drivers/media/platform/s5p-jpeg/jpeg-core.h:43: warning: "RST" redefined
>>     43 | #define RST                             0xd0
>> ../arch/mips/include/asm/mach-rc32434/rb.h:13: note: this is the location of the previous definition
>>     13 | #define RST             (1 << 15)
>>
>> In file included from ../drivers/media/platform/s5p-jpeg/jpeg-hw-exynos4.c:12:
>> ../drivers/media/platform/s5p-jpeg/jpeg-core.h:43: warning: "RST" redefined
>>     43 | #define RST                             0xd0
>> ../arch/mips/include/asm/mach-rc32434/rb.h:13: note: this is the location of the previous definition
>>     13 | #define RST             (1 << 15)
>>
>> In file included from ../drivers/media/platform/s5p-jpeg/jpeg-core.c:31:
>> ../drivers/media/platform/s5p-jpeg/jpeg-core.h:43: warning: "RST" redefined
>>     43 | #define RST                             0xd0
>> ../arch/mips/include/asm/mach-rc32434/rb.h:13: note: this is the location of the previous definition
>>     13 | #define RST             (1 << 15)
>>
>> Fixes: bb677f3ac434 ("[media] Exynos4 JPEG codec v4l2 driver")
>> Reported-by: kernel test robot <lkp@...el.com>
>> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
>> Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
>> Cc: linux-media@...r.kernel.org
>> Cc: Andrzej Pietrasiewicz <andrzejtp2010@...il.com>
>> Cc: Jacek Anaszewski <jacek.anaszewski@...il.com>
>> Cc: Sylwester Nawrocki <s.nawrocki@...sung.com>
>> Cc: linux-arm-kernel@...ts.infradead.org
>> ---
>>   drivers/media/platform/s5p-jpeg/jpeg-core.c |    2 +-
>>   drivers/media/platform/s5p-jpeg/jpeg-core.h |    2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> --- linux-next-20210903.orig/drivers/media/platform/s5p-jpeg/jpeg-core.c
>> +++ linux-next-20210903/drivers/media/platform/s5p-jpeg/jpeg-core.c
>> @@ -1203,7 +1203,7 @@ static bool s5p_jpeg_parse_hdr(struct s5
>>   			break;
>>   
>>   		/* skip payload-less markers */
>> -		case RST ... RST + 7:
>> +		case RSET ... RSET + 7:
>>   		case SOI:
>>   		case EOI:
>>   		case TEM:
>> --- linux-next-20210903.orig/drivers/media/platform/s5p-jpeg/jpeg-core.h
>> +++ linux-next-20210903/drivers/media/platform/s5p-jpeg/jpeg-core.h
>> @@ -40,7 +40,7 @@
>>   #define TEM				0x01
>>   #define SOF0				0xc0
>>   #define DHT				0xc4
>> -#define RST				0xd0
>> +#define RSET				0xd0
>>   #define SOI				0xd8
>>   #define EOI				0xd9
>>   #define	SOS				0xda
> 
> I don't like this change, for a couple reasons:
> 
> 1. the JPEG marker is "RST" (actually, "RST0") instead of "RSET"
>     (see pag. 36 https://www.w3.org/Graphics/JPEG/itu-t81.pdf). The
>     close it sticks with the JPEG standard, the better;

It looks like RST0 would work fine here.
[builds] Yes, it does.

> 2. better to add a namespace here, as other JPEG markers like SOS,
>     SOI and EOI seems to have a high chance of happening somewhere
>     else on other kernel headers in the future.

Makes sense.

> So, IMO, the best would be to rename all those markers as a hole, with
> something similar to:
> 
> 	$ for i in TEM SOF0 DHT RST SOI EOI SOS DQT DHP; do sed "s,\b$i\b,JPEG_MARKER_$i,g" -i drivers/media/platform/s5p-jpeg/*.[ch]; done
> 
> and manually adjust the patch, as at least this hunk could be
> improved:
> 
> 	@@ -187,11 +187,11 @@ struct s5p_jpeg_marker {
> 	  * @fmt:       driver-specific format of this queue
> 	  * @w:         image width
> 	  * @h:         image height
> 	- * @sos:       SOS marker's position relative to the buffer beginning
> 	- * @dht:       DHT markers' positions relative to the buffer beginning
> 	- * @dqt:       DQT markers' positions relative to the buffer beginning
> 	- * @sof:       SOF0 marker's position relative to the buffer beginning
> 	- * @sof_len:   SOF0 marker's payload length (without length field itself)
> 	+ * @sos:       JPEG_MARKER_SOS marker's position relative to the buffer beginning
> 	+ * @dht:       JPEG_MARKER_DHT markers' positions relative to the buffer beginning
> 	+ * @dqt:       JPEG_MARKER_DQT markers' positions relative to the buffer beginning
> 	+ * @sof:       JPEG_MARKER_SOF0 marker's position relative to the buffer beginning
> 	+ * @sof_len:   JPEG_MARKER_SOF0 marker's payload length (without length field itself)
> 	  * @size:      image buffer size in bytes
> 	  */
> 
> to avoid repeating the word marker.

OK, I can do that.

thanks.

-- 
~Randy