From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: barebox@lists.infradead.org
Subject: [PATCH] spi: mvebu: use wait_on_timeout instead of a loop with udelay.
Date: Thu, 8 Dec 2016 11:20:50 +0100 [thread overview]
Message-ID: <20161208102050.7617-1-u.kleine-koenig@pengutronix.de> (raw)
This looks nicer and reduces the time to transfer 40 MB at 50 MHz from
203 seconds to 87 seconds.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
Side note:
When using
while(!(readl(p->base + SPI_IF_CTRL) & IF_READ_READY))
;
return 0;
instead, the time goes down to 24 seconds.
I think the culprit is that get_time_ns (which is used in
wait_on_timeout) handles conversion from timer values to ns.
I didn't look into that (yet) but I think this could be improved by
changing from:
int __ret = 0;
uint64_t __to_start = get_time_ns();
while (!(condition)) {
if (is_timeout(__to_start, (timeout))) {
__ret = -ETIMEOUT;
break;
}
}
return __ret;
to something like:
int __ret = 0;
uint64_t __to_start_cyc = get_time_cyc();
uint64_t __timeout_cyc = ns2cyc(timeout);
while (!(condition)) {
if (is_timeout_cyc(__to_start_cyc, __timeout_cyc)) {
__ret = -ETIMEOUT;
break;
}
}
return __ret;
Here only a single conversion between cyc and ns is done and
is_timeout_cyc is cheap as it doesn't need to convert.
The obvious downside is that time_ns isn't updated that often. But it
could still be worth the effort.
Best regards
Uwe
drivers/spi/mvebu_spi.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/drivers/spi/mvebu_spi.c b/drivers/spi/mvebu_spi.c
index 68838c0ce184..f24508a7bc5d 100644
--- a/drivers/spi/mvebu_spi.c
+++ b/drivers/spi/mvebu_spi.c
@@ -249,13 +249,11 @@ static int mvebu_spi_setup(struct spi_device *spi)
static inline int mvebu_spi_wait_for_read_ready(struct mvebu_spi *p)
{
- int timeout = 100;
- while ((readl(p->base + SPI_IF_CTRL) & IF_READ_READY) == 0 &&
- timeout--)
- udelay(1);
- if (timeout < 0)
- return -EIO;
- return 0;
+ int ret;
+
+ ret = wait_on_timeout(100 * USECOND,
+ readl(p->base + SPI_IF_CTRL) & IF_READ_READY);
+ return ret;
}
static int mvebu_spi_do_transfer(struct spi_device *spi,
--
2.10.2
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
next reply other threads:[~2016-12-08 10:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-08 10:20 Uwe Kleine-König [this message]
2016-12-12 5:45 ` Sascha Hauer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161208102050.7617-1-u.kleine-koenig@pengutronix.de \
--to=u.kleine-koenig@pengutronix.de \
--cc=barebox@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox