From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shinya Kuribayashi Date: Tue, 25 Aug 2009 22:25:58 +0900 Subject: [U-Boot] PATCH mtd CFI flash: timeout calculation underflow if imprecise 1kHz timer: fix In-Reply-To: <4A925011.9080906@imagos.it> References: <4A925011.9080906@imagos.it> Message-ID: <4A93E666.4080404@pobox.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Renato Andreola wrote: > From 21d84ab72266f118794233176bd356d8b1cfdf35 Mon Sep 17 00:00:00 2001 > From: Renato Andreola > Date: Fri, 21 Aug 2009 18:05:51 +0200 > Subject: [PATCH] drivers/mtd/cfi_flash: precision and underflow problem in tout calculation > > With old configuration it could happen tout=0 if CONFIG_SYS_HZ<1000. > > Signed-off-by: Alessandro Rubini Renato Andreola > --- > drivers/mtd/cfi_flash.c | 8 +++++--- > 1 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c > index 81ac5d3..0d8fc54 100644 > --- a/drivers/mtd/cfi_flash.c > +++ b/drivers/mtd/cfi_flash.c > @@ -660,9 +660,11 @@ static int flash_status_check (flash_info_t * info, flash_sect_t sector, > ulong start; > > #if CONFIG_SYS_HZ != 1000 > - tout *= CONFIG_SYS_HZ/1000; > -#endif > - > + if ((ulong)CONFIG_SYS_HZ > 100000) > + tout *= (ulong)CONFIG_SYS_HZ/1000; /* for a big HZ, avoid overflow */ > + else > + tout = DIV_ROUND_UP(tout*(ulong)CONFIG_SYS_HZ, 1000); > +#endif > /* Wait for command completion */ > start = get_timer (0); > while (flash_is_busy (info, sector)) { What should to be fixed first in this case, would be your CONFIG_SYS_HZ setting, that is NIOS2? timer implementation, yeah really. But I would also point out that there is another case flash_status_check() doensn't work as expected. One of my colleagues found that with some flash device(s) (I don't recall precisely, sorry), 'tout' would be probed to be zero. In that case, a workaround something like above still doesn't work. We have not sorted out where the problem is; it might be in cfi_flash.c, or in the flash device itself. This is observed with v2009.03 release, and we've been having a workaround for it for months. I'd like to have a look someday. Anyway, checking to see if 'tout' is zero or not would be sometimes worth a try, when you think cfi_flash.c doesn't work as expected. Just for your information,