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authorMike Dunn <mikedunn@newsguy.com>2013-01-07 13:55:13 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-01-17 08:46:26 -0800
commit3e524dfa0c7d0b65569fb403a1702c18ca9561ad (patch)
treeb6c7dc66c0b274e57060ce498ad36730479323cf /sound
parentd512778257bc4c5c83c110094cd306d136a14714 (diff)
ALSA: pxa27x: fix ac97 warm reset
commit 3b4bc7bccc7857274705b05cf81a0c72cfd0b0dd upstream. This patch fixes some code that implements a work-around to a hardware bug in the ac97 controller on the pxa27x. A bug in the controller's warm reset functionality requires that the mfp used by the controller as the AC97_nRESET line be temporarily reconfigured as a generic output gpio (AF0) and manually held high for the duration of the warm reset cycle. This is what was done in the original code, but it was broken long ago by commit fb1bf8cd ([ARM] pxa: introduce processor specific pxa27x_assert_ac97reset()) which changed the mfp to a GPIO input instead of a high output. The fix requires the ac97 controller to obtain the gpio via gpio_request_one(), with arguments that configure the gpio as an output initially driven high. Tested on a palm treo 680 machine. Reportedly, this broken code only prevents a warm reset on hardware that lacks a pull-up on the line, which appears to be the case for me. Signed-off-by: Mike Dunn <mikedunn@newsguy.com> Signed-off-by: Igor Grinberg <grinberg@compulab.co.il> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound')
-rw-r--r--sound/arm/pxa2xx-ac97-lib.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/sound/arm/pxa2xx-ac97-lib.c b/sound/arm/pxa2xx-ac97-lib.c
index 8cfb2c0efcb2..bd3ba8812e13 100644
--- a/sound/arm/pxa2xx-ac97-lib.c
+++ b/sound/arm/pxa2xx-ac97-lib.c
@@ -18,6 +18,7 @@
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/io.h>
+#include <linux/gpio.h>
#include <sound/ac97_codec.h>
#include <sound/pxa2xx-lib.h>
@@ -344,8 +345,21 @@ int __devinit pxa2xx_ac97_hw_probe(struct platform_device *dev)
}
if (cpu_is_pxa27x()) {
- /* Use GPIO 113 as AC97 Reset on Bulverde */
+ /*
+ * This gpio is needed for a work-around to a bug in the ac97
+ * controller during warm reset. The direction and level is set
+ * here so that it is an output driven high when switching from
+ * AC97_nRESET alt function to generic gpio.
+ */
+ ret = gpio_request_one(reset_gpio, GPIOF_OUT_INIT_HIGH,
+ "pxa27x ac97 reset");
+ if (ret < 0) {
+ pr_err("%s: gpio_request_one() failed: %d\n",
+ __func__, ret);
+ goto err_conf;
+ }
pxa27x_assert_ac97reset(reset_gpio, 0);
+
ac97conf_clk = clk_get(&dev->dev, "AC97CONFCLK");
if (IS_ERR(ac97conf_clk)) {
ret = PTR_ERR(ac97conf_clk);
@@ -388,6 +402,8 @@ EXPORT_SYMBOL_GPL(pxa2xx_ac97_hw_probe);
void pxa2xx_ac97_hw_remove(struct platform_device *dev)
{
+ if (cpu_is_pxa27x())
+ gpio_free(reset_gpio);
GCR |= GCR_ACLINK_OFF;
free_irq(IRQ_AC97, NULL);
if (ac97conf_clk) {