[U-Boot] PATCH mtd CFI flash: timeout calculation underflow if imprecise 1kHz timer: fix

Jean-Christophe PLAGNIOL-VILLARD
2009-08-06T20:26:15Z

On 15:09 Thu 06 Aug , Renato Andreola wrote:
> From 3723c8437d8c3d2e04bc3bc1de9c21b33072ab08 Mon Sep 17 00:00:00 2001
> From: Renato Andreola <renato.andreola@imagos.it>
> Date: Thu, 6 Aug 2009 14:49:59 +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
> solved avoiding the preprocessor conditional and introducing a compile
> time branch between a high freq case and a slow freq case.
>
> Signed-off-by: Renato Andreola renato.andreola at imagos.it
> ---
> drivers/mtd/cfi_flash.c | 7 ++++---
> 1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
> index 81ac5d3..b118f71 100644
> --- a/drivers/mtd/cfi_flash.c
> +++ b/drivers/mtd/cfi_flash.c
> @@ -659,9 +659,10 @@ 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 (CONFIG_SYS_HZ > 10000)
> + tout *= CONFIG_SYS_HZ/1000; /* for a big HZ, avoid
> overflow */
> + else
> + tout = tout * CONFIG_SYS_HZ / 1000 + 1;
as we are all supposed to have CONFIG_SYS_HZ at 1000 (mandtory)
to have cfi, tftp & co working perfectly I do not thing this is a good idea

as you will need to fix each part of u-boot that use CONFIG_SYS_HZ
which make no sense

the best will be to simply fix your timer

Best Regards,
J.