Re: [U-Boot] [Patch v3] cmd/gpt: Support gpt command for all devices

13 Oct 2013

On Fri, Oct 11, 2013 at 09:13:22AM +0200, Piotr Wilczek wrote:
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Dear Egbert Eich,
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-----Original Message-----
From: Egbert Eich [mailto:egbert.eich@gmail.com]
Sent: Friday, October 04, 2013 6:53 PM
To: u-boot@lists.denx.de
Cc: Piotr Wilczek; Tom Rini; Egbert Eich; Egbert Eich
Subject: [Patch v3] cmd/gpt: Support gpt command for all devices
From: Egbert Eich eich@suse.com
The gpt command was only implemented for mmc devices. There is no
reason why this command should not be generalized and be applied all
other storage device classes.
This change both simplifies the implementation and eliminates a build
failure for systems that don't support mmcs.
Signed-off-by: Egbert Eich eich@suse.com
Changes for v2:

Coding style cleanup.

Changes for v3:

Removed wrong '&'
Removed unused variable
Fixed argument checking

Spotted by Piotr Wilczek p.wilczek@samsung.com
common/cmd_gpt.c | 45 +++++++++++++++++++--------------------------
 1 file changed, 19 insertions(+), 26 deletions(-)

diff --git a/common/cmd_gpt.c b/common/cmd_gpt.c index a46f5cc..17b1180
100644
--- a/common/cmd_gpt.c
+++ b/common/cmd_gpt.c
[..]
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@@ -287,27 +279,28 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int
[..]
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/* device: 'mmc' */


if (strcmp(argv[2], "mmc") == 0) {


	/* check if 'dev' is a number */


	for (pstr = argv[3]; *pstr != '\0'; pstr++)


		if (!isdigit(*pstr)) {


			printf("'%s' is not a number\n",


				argv[3]);


			return CMD_RET_USAGE;


		}


	dev = (int)simple_strtoul(argv[3], NULL, 10);


	/* write to mmc */


	if (gpt_mmc_default(dev, argv[4]))


		return CMD_RET_FAILURE;




char *ep;


block_dev_desc_t *blk_dev_desc;



This probably should be at the beginning of the function
I personally prefer to keep symbols as local as possible (ie. declare them
in the block they are used in if they are just used within a single block) 
for the following rasons:
1. It makes the code more readable ie. the definition is closeby to
   the location where it is used and doesn't require scrolling to 
   the beginning of a function and the scope of the variable is is 
   much more obvious.
2. The compiler can optimize much better as it knows that a variable 
   can be discarded at the end of the block also by reusing stack 
   slots stack sapce can be used much more efficiently by the compiler.
I agree that in the case at hand the second argument is not too
relevant, it is more a coding style issue. If there is a coding
style requirement to have those definitions at the beginning of
the function I will create a new patch.
[..]
...
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blk_dev_desc = get_dev(argv[2], dev);


if (!blk_dev_desc) {


	printf("%s: %s dev %d NOT available\n",


	       __func__, argv[2], dev);



I think it is not necessary since the mmc subsystem prints 'MMC Device not
found'.
I've done a quick look over the code - of all subsystems MMC seems to be 
the only one which prints a message when its get_dev() method is called 
but no device is found. Therefore I'd prefer to leave this there.
...
Except minor comments this patch looks good to me.
I tested it on mmc device (Trats2) and works well.
Ok, thanks!
...
Tested-by: Piotr Wilczek p.wilczek@samsung.com
Thanks a lot for testing!
Cheers,
    Egbert.

    