From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stefan Roese <sr@denx.de>
Date: Mon, 27 Feb 2012 11:26:18 +0100
Subject: [U-Boot] [PATCH 03/11] st_smi: Return error in case TFF is not
	set
In-Reply-To: <1330086194-21762-4-git-send-email-amit.virdi@st.com>
References: <1330086194-21762-1-git-send-email-amit.virdi@st.com>
	<1330086194-21762-4-git-send-email-amit.virdi@st.com>
Message-ID: <201202271126.18256.sr@denx.de>
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To: u-boot@lists.denx.de

On Friday 24 February 2012 13:23:06 Amit Virdi wrote:
> Curently the code makes wrong assumption that the Transfer finished flag
> shall be set within the stipulated time. However, there may occur a
> scenario in which the TFF flag is not set. Return error in that case.
> 
> Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
> Signed-off-by: Amit Virdi <amit.virdi@st.com>
> ---
>  drivers/mtd/st_smi.c |   22 ++++++++++++++--------
>  1 files changed, 14 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mtd/st_smi.c b/drivers/mtd/st_smi.c
> index 82f1fe1..ec19b0d 100644
> --- a/drivers/mtd/st_smi.c
> +++ b/drivers/mtd/st_smi.c
> @@ -58,13 +58,15 @@ static struct flash_dev flash_ids[] = {
>   *
>   * Wait until TFF is set in status register
>   */
> -static void smi_wait_xfer_finish(int timeout)
> +static int smi_wait_xfer_finish(int timeout)
>  {
> -	while (timeout--) {
> +	do {
>  		if (readl(&smicntl->smi_sr) & TFF)
> -			break;
> +			return 0;
>  		udelay(1000);
> -	}
> +	} while (timeout--);
> +
> +	return -1;

Somewhat unrelated to the patch topic, but I don't really like this kind of 
timeout loops. Since it always adds at least 1ms delay after initial failing 
test. Better use something like this:

static int smi_wait_xfer_finish(int timeout)
{
	ulong start = get_timer(0);

	while (get_timer(start) < timeout) {
		if (readl(&smicntl->smi_sr) & TFF)
			return 0;

		/* Try again after 100usec */
		udelay(100);
	}

	return -1;
}

You could tune this udelay(100) down more or even remove it completely.

But such a change could be done in a addon cleanup patch, changing all timeout 
loops this way. I suggest you take a look at my version, here these loops are 
changes. In the designware networking driver as well, iirc.

Thanks,
Stefan

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