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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h b/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h
index ec0f0b0b6744b9afba76c6b482cf888b7b530b81..18c083e76de0db4c5985731ebfbe168481f78e33 100644 (file)
--- a/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h
+++ b/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h
@@ -460,6 +460,9 @@
        GPIO76_LCD_PCLK,        \
        GPIO77_LCD_BIAS
 
+/* these enable a work-around for a hw bug in pxa27x during ac97 warm reset */
+#define GPIO113_AC97_nRESET_GPIO_HIGH MFP_CFG_OUT(GPIO113, AF0, DEFAULT)
+#define GPIO95_AC97_nRESET_GPIO_HIGH MFP_CFG_OUT(GPIO95, AF0, DEFAULT)
 
 extern int keypad_set_wake(unsigned int on);
 #endif /* __ASM_ARCH_MFP_PXA27X_H */

diff --git a/arch/arm/mach-pxa/pxa27x.c b/arch/arm/mach-pxa/pxa27x.c
index bc5a98ebaa72872033ab49c7e535f4d5bc1317f7..a9447f9fe66e35323e2c405bb9c2a1e6bf15ba22 100644 (file)
--- a/arch/arm/mach-pxa/pxa27x.c
+++ b/arch/arm/mach-pxa/pxa27x.c
@@ -47,9 +47,9 @@ void pxa27x_clear_otgph(void)
 EXPORT_SYMBOL(pxa27x_clear_otgph);
 
 static unsigned long ac97_reset_config[] = {
-       GPIO113_GPIO,
+       GPIO113_AC97_nRESET_GPIO_HIGH,
        GPIO113_AC97_nRESET,
-       GPIO95_GPIO,
+       GPIO95_AC97_nRESET_GPIO_HIGH,
        GPIO95_AC97_nRESET,
 };
 

diff --git a/sound/arm/pxa2xx-ac97-lib.c b/sound/arm/pxa2xx-ac97-lib.c
index 9ba64d5e4cd657eb1339c7e6dc276ce5ab2320d7..52a43189b7d3736dcc63283f5112289c51efc458 100644 (file)
--- a/sound/arm/pxa2xx-ac97-lib.c
+++ b/sound/arm/pxa2xx-ac97-lib.c
@@ -17,6 +17,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/module.h>
+#include <linux/gpio.h>
 
 #include <sound/ac97_codec.h>
 #include <sound/pxa2xx-lib.h>
@@ -343,8 +344,21 @@ 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);
@@ -387,6 +401,8 @@ 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) {