diff mbox

[U-Boot,V2,02/13] spl: mmc: add break statements in spl_mmc_load_image()

Message ID 1446024210-16517-3-git-send-email-nikita@compulab.co.il
State Superseded
Delegated to: Tom Rini
Headers show

Commit Message

Nikita Kiryanov Oct. 28, 2015, 9:23 a.m. UTC
The original intention of the mmc load_image() function was to try multiple
boot modes before failing. This is evident by the lack of break statements
in the switch, and the following line in the default case:
puts("spl: mmc: no boot mode left to try\n");

This implementation is problematic because:
- The availability of alternative boot modes is very arbitrary since it
depends on the specific order of the switch cases. If your boot mode happens to
be the first case, then you'll have a bunch of other boot modes as alternatives.
If it happens to be the last case, then you have none.
- Opting in/out is tied to config options, so the only way for you to prevent an
alternative boot mode from being attempted is to give up on the feature completely.
- This implementation makes the code more complicated and difficult to
understand.

Address these issues by inserting a break statements between the cases to make the
function try only one boot mode.

Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Paul Kocialkowski <contact@paulk.fr>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
---
Changes in V2:
	- Removed hang() in default cases, moved default case into ifdef
	  LIBCOMMON.

 common/spl/spl_mmc.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

Comments

Simon Glass Oct. 29, 2015, 5:19 p.m. UTC | #1
On 28 October 2015 at 03:23, Nikita Kiryanov <nikita@compulab.co.il> wrote:
> The original intention of the mmc load_image() function was to try multiple
> boot modes before failing. This is evident by the lack of break statements
> in the switch, and the following line in the default case:
> puts("spl: mmc: no boot mode left to try\n");
>
> This implementation is problematic because:
> - The availability of alternative boot modes is very arbitrary since it
> depends on the specific order of the switch cases. If your boot mode happens to
> be the first case, then you'll have a bunch of other boot modes as alternatives.
> If it happens to be the last case, then you have none.
> - Opting in/out is tied to config options, so the only way for you to prevent an
> alternative boot mode from being attempted is to give up on the feature completely.
> - This implementation makes the code more complicated and difficult to
> understand.
>
> Address these issues by inserting a break statements between the cases to make the
> function try only one boot mode.
>
> Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
> Cc: Igor Grinberg <grinberg@compulab.co.il>
> Cc: Paul Kocialkowski <contact@paulk.fr>
> Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: Simon Glass <sjg@chromium.org>
> ---
> Changes in V2:
>         - Removed hang() in default cases, moved default case into ifdef
>           LIBCOMMON.
>
>  common/spl/spl_mmc.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)

Reviewed-by: Simon Glass <sjg@chromium.org>
Tom Rini Nov. 3, 2015, 3:56 p.m. UTC | #2
On Wed, Oct 28, 2015 at 11:23:19AM +0200, Nikita Kiryanov wrote:

> The original intention of the mmc load_image() function was to try multiple
> boot modes before failing. This is evident by the lack of break statements
> in the switch, and the following line in the default case:
> puts("spl: mmc: no boot mode left to try\n");
> 
> This implementation is problematic because:
> - The availability of alternative boot modes is very arbitrary since it
> depends on the specific order of the switch cases. If your boot mode happens to
> be the first case, then you'll have a bunch of other boot modes as alternatives.
> If it happens to be the last case, then you have none.
> - Opting in/out is tied to config options, so the only way for you to prevent an
> alternative boot mode from being attempted is to give up on the feature completely.
> - This implementation makes the code more complicated and difficult to
> understand.
> 
> Address these issues by inserting a break statements between the cases to make the
> function try only one boot mode.
> 
> Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
> Cc: Igor Grinberg <grinberg@compulab.co.il>
> Cc: Paul Kocialkowski <contact@paulk.fr>
> Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: Simon Glass <sjg@chromium.org>

Reviewed-by: Tom Rini <trini@konsulko.com>
diff mbox

Patch

diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
index ce58c58..6011f77 100644
--- a/common/spl/spl_mmc.c
+++ b/common/spl/spl_mmc.c
@@ -164,6 +164,7 @@  void spl_mmc_load_image(void)
 		if (!err)
 			return;
 #endif
+		break;
 	case MMCSD_MODE_FS:
 		debug("spl: mmc boot mode: fs\n");
 
@@ -203,6 +204,7 @@  void spl_mmc_load_image(void)
 #endif
 #endif
 #endif
+		break;
 #ifdef CONFIG_SUPPORT_EMMC_BOOT
 	case MMCSD_MODE_EMMCBOOT:
 		/*
@@ -240,15 +242,14 @@  void spl_mmc_load_image(void)
 		if (!err)
 			return;
 #endif
+		break;
 #endif
 	case MMCSD_MODE_UNDEFINED:
-	default:
 #ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
-		if (err)
-			puts("spl: mmc: no boot mode left to try\n");
-		else
-			puts("spl: mmc: wrong boot mode\n");
+	default:
+		puts("spl: mmc: wrong boot mode\n");
 #endif
-		hang();
 	}
+
+	hang();
 }