From: "Jan Lübbe" <jlu@pengutronix.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: barebox-request <barebox@lists.infradead.org>
Subject: Re: [PATCH 10/10] drivers/spi: add driver for the Multichannel SPI controller found in TI SoCs
Date: Wed, 05 Sep 2012 11:20:51 +0200 [thread overview]
Message-ID: <1346836851.3388.6.camel@coredoba.hi.pengutronix.de> (raw)
In-Reply-To: <20120904085858.GT26594@pengutronix.de>
Hi,
On Tue, 2012-09-04 at 10:58 +0200, Sascha Hauer wrote:
> > + for (i = 0; i < len; i++) {
> > + /* wait till TX register is empty (TXS == 1) */
> > + while
> (!(readl(®s->channel[spi->chip_select].chstat) &
> > + OMAP3_MCSPI_CHSTAT_TXS)) {
> > + if (--timeout <= 0) {
> > + printf("SPI TXS timed out, status=0x%
> 08x\n",
> > +
> readl(®s->channel[spi->chip_select].chstat));
> > + return -1;
> > + }
> > + }
>
> Please use a well defined timeout rather than 'poll a million times'
I tried using is_timeout like this:
timer_start = get_time_ns();
while (!(readl(®s->channel[spi->chip_select].chstat) &
OMAP3_MCSPI_CHSTAT_TXS)) {
if (is_timeout(timer_start, SPI_WAIT_TIMEOUT)) {
printf("SPI TXS timed out, status=0x%08x\n",
readl(®s->channel[spi->chip_select].chstat));
return -1;
}
}
With SPI_WAIT_TIMEOUT = MSECOND this results in ~23% more time needed
for reading/writing:
With a simple counter:
barebox@KSP-0500:/ time cp /dev/m25p0.norkernel /dev/null
time: 12639ms
barebox@KSP-0500:/ time cp /dev/m25p0.norkernel /dev/null
time: 12639ms
barebox@KSP-0500:/ time cp /dev/m25p0.norkernel /dev/null
time: 12659ms
With is_timeout():
barebox@KSP-0500:/ time cp /dev/m25p0.norkernel /dev/null
time: 15561ms
barebox@KSP-0500:/ time cp /dev/m25p0.norkernel /dev/null
time: 15564ms
barebox@KSP-0500:/ time cp /dev/m25p0.norkernel /dev/null
time: 15568ms
Is this really acceptable? Is there a way to avoid the overhead of
calling several functions for each loop?
Regards,
Jan
--
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Industrial Linux Solutions | http://www.pengutronix.de/ |
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prev parent reply other threads:[~2012-09-05 9:20 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-03 11:45 Prepare support for TI AM35xx Jan Luebbe
2012-09-03 11:45 ` [PATCH 01/10] drivers/nor/m25p80: add JEDEC ID for Micron/Numonyx SPI NOR flash Jan Luebbe
2012-09-03 11:45 ` [PATCH 02/10] drivers/nor/m25p80: add MEMGETINFO ioctl Jan Luebbe
2012-09-04 8:20 ` Sascha Hauer
2012-09-03 11:45 ` [PATCH 03/10] Makefile: add target to produce a SPL compatible uimage Jan Luebbe
2012-09-03 16:22 ` Jean-Christophe PLAGNIOL-VILLARD
2012-09-03 11:45 ` [PATCH 04/10] scripts: add tool to create image for SPI boot on AM35xx Jan Luebbe
2012-09-04 8:27 ` Sascha Hauer
2012-09-03 11:46 ` [PATCH 05/10] common: split out meminfo output and make it optional Jan Luebbe
2012-09-03 11:46 ` [PATCH 06/10] omap: add SPI as a boot mode for xload Jan Luebbe
2012-09-03 16:24 ` Jean-Christophe PLAGNIOL-VILLARD
2012-09-04 7:41 ` Jan Weitzel
2012-09-03 11:46 ` [PATCH 07/10] drivers/net/ksz8864rmn: add driver for Micrel KSZ8864RMN Ethernet Switch Jan Luebbe
2012-09-03 11:46 ` [PATCH 08/10] drivers/net: add driver for the EMAC device found in some TI SoCs Jan Luebbe
2012-09-03 16:27 ` Jean-Christophe PLAGNIOL-VILLARD
2012-09-04 8:42 ` Sascha Hauer
2012-09-03 11:46 ` [PATCH 09/10] omap3: allow enabling clocks for UART3, MMC1 and SPI Jan Luebbe
2012-09-04 8:48 ` Sascha Hauer
2012-09-05 9:28 ` Jan Lübbe
2012-09-03 11:46 ` [PATCH 10/10] drivers/spi: add driver for the Multichannel SPI controller found in TI SoCs Jan Luebbe
2012-09-03 16:32 ` Jean-Christophe PLAGNIOL-VILLARD
2012-09-04 8:58 ` Sascha Hauer
2012-09-05 9:20 ` Jan Lübbe [this message]
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