From: Simon Pearson <spearson@acumalabs.com>
To: grant.likely@secretlab.ca, linus.walleij@linaro.org
Cc: shawn.guo@linaro.org, linux-kernel@vger.kernel.org
Subject: [PATCH 001/001] gpio-mxs: Select faster gpio-generic set methods
Date: Fri, 21 Jun 2013 11:14:07 -0700 [thread overview]
Message-ID: <51C497EF.1070108@acumalabs.com> (raw)
From: Simon Pearson <spearson@acumalabs.com>
Kernel 3.8.4. By defining both the set and clear registers,
the speed of the gpio isimproved. gpio-generic.c, selects the
bgpio_set_with_clear() which isfaster than the current
bgpio_set_set(). This has performance implications for all
bitbang drivers (i2c, spi, etc). Slow SPI as compared to
2.6.35.33 improved by a factor of 10 (80kHz CLK to 800kHz CLK).
Signed-off-by: Simon Pearson <spearson@acumalabs.com>
---
--- a/drivers/gpio/gpio-mxs.c.orig 2013-03-20 13:11:19.000000000 -0700
+++ b/drivers/gpio/gpio-mxs.c 2013-06-21 10:02:33.000000000 -0700
@@ -292,7 +292,8 @@ static int mxs_gpio_probe(struct platfor
err = bgpio_init(&port->bgc, &pdev->dev, 4,
port->base + PINCTRL_DIN(port),
- port->base + PINCTRL_DOUT(port), NULL,
+ port->base + PINCTRL_DOUT(port) + MXS_SET,
+ port->base + PINCTRL_DOUT(port) + MXS_CLR,
port->base + PINCTRL_DOE(port), NULL, 0);
if (err)
goto out_irqdesc_free;
next reply other threads:[~2013-06-21 18:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-21 18:14 Simon Pearson [this message]
2013-06-24 6:59 ` [PATCH 001/001] gpio-mxs: Select faster gpio-generic set methods Shawn Guo
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